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How can society learn from echolocation, and what are some ways that we can use echolocation for our benefit, could it possibly be used to innovate in technology? How?

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How does echolocation compare to human hearing? Does pressure and temperature have any effect on echolocation

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Echolocation occurs when an animal emits a sound wave that bounces off an object. Then, the sound wave that returns provides details about the surrounding object’s distance and size relative to the origin. There are several methods for echolocation which include, using the ability of vibrating their throats and flapping their wings. In the ocean, sound travels five times faster than in air. Most marine mammals echolocation sounds carry a frequency much higher than humans ability to hear, with the exception of orcas and some dolphins. These marine animals use echolocation for self-defense and hunting. However, humans who are blind or have significant lack of vision, use echolocation to perform daily activities. Echolocation among humans is something that needs to be taught, how may someone go about learning this ?

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Nature's own sonar system, echolocation occurs when an animal emits a sound wave that bounces off an object, returning an echo that provides information about the object's distance and size.

Over a thousand species echolocate, including most bats, all toothed whales, and small mammals. Many are nocturnal, burrowing, and ocean-dwelling animals that rely on echolocation to find food in an environment with little to no light. Animals have several methods for echolocation, from vibrating their throats to flapping their wings.

Nocturnal oilbirds and some swiftlets, some of which hunt in dark cave environments, "produce short clicks with their syrinx, the vocal organ of birds," Kate Allen, a postdoctoral fellow in the Department of Psychological and Brain Studies at John Hopkins University, says by email.

Some people can also echolocate by clicking their tongues, a behavior shared by only a few other animals, including tenrecs, a shrew-like animal from Madagascar, and the Vietnamese pygmy dormouse, which is effectively blind.

Bat signals

Bats are the ultimate poster animal for echolocation, using their built-in sonar to pursue fast-flying prey at night.

Most bats, such as the tiny Daubenton's bat, contract their larynx muscles to make sounds above the range of human hearing-the batty equivalent of a shout, Allen says. (Related: When it comes to echolocation, some bats just wing it.)

Bat calls vary wildly among species, allowing them to distinguish their voices among other bats in the neighborhood. Their calls are also specific to a particular environment and prey type: The European bat "whispers" in the presence of moths to avoid detection.

Some moths, though, have evolved their own defenses against echolocating bats. The tiger moth flexes the tymbal organ on either side of its thorax to produce clicks, which jams bat sonar and keeps the predators at bay.

As expert echolocators, some bats can zero in on objects as small as 0.007 inch, about the width of a human hair. Because insects are always on the move, bats have to click continuously, sometimes making 190 calls a second. Even with such difficult quarry, the predators can still eat half their weight in insects each night.

Leaf-nosed bats make echolocation calls through their large, intricately folded noses, which helps focus sounds that bounces back. Some species can also rapidly change their ear shape to accurately pick up incoming signals.

A few fruit bats, such as the South Asian lesser dawn bat, even make clicks by flapping their wings, a recent discovery.

Ocean soundwaves

Echolocation is a logical strategy in the ocean, where sound travels five times faster than in air.

Dolphins and other toothed whales, such as the beluga, echolocate via a specialized organ called the dorsal bursae, which sits at the top of their head, close to the blowhole. ( Read how whales have a "sonar beam" for targeting prey.)

A fat deposit in this area, called the melon, decreases impedance, or resistance to soundwaves, between the dolphin's body and the water, making the sound clearer, says Wu-Jung Lee, a senior oceanographer at the University of Washington Applied Physics Laboratory.

Another fat deposit, stretching from a whale's lower jaw up to its ear, clarifies the echo that returns from prey, such as fish or squid.

Harbor porpoises, a favorite prey of orcas, make extremely speedy, high-frequency echolocation clicks that their predators can't hear, allowing them to remain incognito.

Most marine mammal echolocation sounds are too high for humans to hear, with the exception of sperm whales, orcas, and some dolphin species, Lee adds.

Navigating by sound

In addition to hunting or self-defense, some animals echolocate to navigate through their habitats.

For instance, big brown bats, which are widespread throughout the Americas, use their sonar to weave their way through noisy environments, such as forests abuzz with other animal calls.

Amazon river dolphins may also echolocate to move around tree branches and other obstacles created by seasonal flooding, Lee says.

Most humans who echolocate are blind or vision-impaired and use the skill to go about their daily activities. Some make clicks, either with their tongues or an object, like a cane, and then navigate via the resulting echo. Brain scans of echolocating humans show the part of the brain that processes vision is employed during this process. ( Read how blind people use sonar.)

"Brains don't like undeveloped real estate," Allen says, so "it's too metabolically expensive to maintain" echolocation in people who don't need it.

Even so, humans are remarkably adaptable, and research shows that, with patience, we can teach ourselves to echolocate.

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Echolocation is nature's built-in sonar. Here's how it works.

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Nature's own sonar system, echolocation occurs when an animal emits a sound wave that bounces off an object, returning an echo that provides information about the object's distance and size. Over a thousand species echolocate, including most bats, all toothed whales, and small mammals.

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The Contributions of Ecolocation Within Society:

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The Contributions of Ecolocation Within Society:

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Inspired by echolocation, engineers have developed sonar systems for robots and drones, enabling them to navigate and avoid obstacles in real-time. These technologies can be used in applications of many situations, including search and rescue missions and automated delivery services. These principles of echolocation have been applied to create devices that help the visually impaired individuals navigate their environments. In fact, research into how animals use echolocation has led the development of more sophisticated hearing aids. However, the question persists, how can the principles of echolocation be further integrated to enhance environmental sustainability?

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Introduction
Dolphins utilize echolocation to discover things in their surroundings. The clicking-noises they utter bounce off things under the water & goes back to this smart mammal. This assists them to measure size & the distance separating them & far away things.
What is Echolocation?
The concept of dispatching a sound into the atmosphere, then calculating the time it takes to echo back is called echolocation.
Application of Echolocation In the World
Echolocation isn't only restricted to dolphins. People accommodated this rule into sonar, that sends pings inside the water & listens for the echoes. The achievement of sonar later developed into radar, which happens to be the same concept, but having radio waves into the air.
Devices For The Blind People
Those who could profit most from modern sound tech are the blind. Most of the blind people utilize sound like a director, many of them exercising long & hard enough to obtain a kind of echolocation. This knowledge has been adopted to develop devices to assist the blind pilot the world properly.

Understanding the limits to which echolocation may be utilized, scientists made the subsequent leap in its development involving the utilization of lasers, presently recognised as Lidar. This happens to be a compound remote-sensing tech utilizing laser-light to highly sample the facade of an object. Now, it's being utilized by archaeologists to investigate the subterranean layers of the planet.
How Do We Use Lidar Technology?
In contemporary years, archaeologists have begun utilizing Lidar to draft the height of highlights on the spot. Lidar assisted the scientists to travel 2,000 km in a comparatively short span of time. Reaching that big land by hand, utilizing ground entering radar, could have used decades. However, Lidar's application doesn't end there.

Luckily, a close kin of lidar called the phased-array is an excellent workaround. It's able to broadcast radio-waves in a given direction utilizing a microscopic-array of unique antennas collectively synced. By observing the timing - or phase - within each antenna transmitting its signal, technicians can "steer" a single signal in a particular direction. This is the initial step in utilizing lidar for autonomous-vehicles.

Additionally, Lidar can't work it alone: it can't scan signs because they're flat; the operations can be interrupted quickly by restricted visibility.

Therefore, to operate in a car, lidar must work mutually with additional systems: its relatives' radar & ultrasound & conventional visible-light cameras assist Lidar.

Dr Seth Horowitz happens to be utilizing the ideal by which bats rule sound like the solution to unlocking a distinct class of assistive mechanisms which could permit a blind individual to travel the world with unmatched freedom. He wishes to accomplish more compared to early machines which were no more compared to indicators which informed the user of obstructions or objects nearby.

While Lidar can be the subsequent-wave of the future technology for realizing autonomous vehicles, helping the blind in learning their surroundings with sound, & improving archaeologists' capacity to outline the past, there're still numerous interests with its restrictions & costs.
Conclusion
Scientists yet have much development, innovation, & testing to work on before Lidar may be reliably utilized to operate autonomous-vehicles. And there're yet more difficulties which Lidar can yet be the resolution for. If you want to read more about this, visit here;
https://www.iqsdirectory.com/resources/how-echolocation-inspired-lidar-and-the-technologies-behind-it/ Author Biodata
Anna Kucirkova works as a copywriter for over 4 years. She speaks 3 languages, loves travelling and has a passion for kids and writing. While she has been to many places in Europe and South East Asia, she still wants to explore the rest of the world.

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Echolocation And Its Technological Developments - GIS Resources

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Authored By: Introduction Dolphins utilize echolocation to discover things in their surroundings. The clicking-noises they utter bounce off things under the water & goes back to this smart mammal.

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Echolocation For Blind Individuals in Society

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Echolocation For Blind Individuals in Society

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Echolocation is a mechanism in animals that allows then to gain information through sound. It works by prodoucing sound and listening to the reflection from the environment. This way animals can gain information about the size, shape, distance, and event exture of objects near them.

Echolocation can be learned in blind individuals. Approximately 20%-30% of blind people know how to echolocate. For humans, cane taps, snaps, humming and mouth clicks are common echolocating noises while for animals it is usually the sound of their prey. Experienced individuals in echolocation can even tell the texture of materials .

Learning how to echolocate ultimately, increases the safety of blind people and benefits their daily lives as they are able to gain independence in complex environments.

People can learn the process of echolocation through specific training which includes walking towards a wall and only stopping just before the wall depending on the reflection of your sound. One can increase the difficulty by adding obstacles that affect the reflection of sound.

Are there any physiological changes that occur as a result of a blind individual learning to echolocate, if so what?

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Find out what echolocation is, including its benefits, learning process, and how it works.

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Climate change is known to affect the structure of animals but the impacts that it has on their mechanisms are still unknown. However, studies have concluded that there is a link between climate change (therefore increasing temperature) and the ability of bats to echolocate.

As animal sounds are adapted to the acoustic properties of their habitat, that specific call is most effective to make sound transmission loss reduced. Furthermore, sound attenuation is a direct consequence of an increase in temperature, meaning that climate change has the ability to affect the sounds produced by echolocating animals like bats.

Echolocation works through the echoes on an environment which is largely dependent on the atmosphereic attenuation in the air at that time in that location. As temperature increases, atmospheric attentuation also increases. Therefore creating a shorter prey detection distance and smaller prey detection volumes for bats.

Bats with lower frequency calls will benefit from climate change while those with higher frequency calls will likely die off as a result of differences in foraging and reproductive success.

This ultimately leads me to question; why is it that sound attenuation only affects bats with higher frequency calls in comparison to species with higher frequency calls?

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Abstract

Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronounced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a crossover frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey.

Keywords: echolocation, foraging, global warming, sensory ecology, species interactions

1. Introduction

Depending on the magnitude of CO ₂ emission, the global surface temperature is predicted to rise by 1.1-6.4°C during the twenty-first century [ 1]. Although our planet has only warmed by approximately 0.6°C during the past century [ 1], ecological responses are already occurring [ 2- 6]. Direct temperature-related effects on individuals and species have been observed, such as spring advancement of phenology, expansion of species distributions to higher latitudes and altitudes and reduction of body size [ 2, 3, 6]. Besides these direct effects, climate change also alters species interactions by differentially affecting interacting species [ 4, 7], leading to complex, nonlinear ecological response patterns. In contrast to the ecological effects of global warming, the direct mechanisms that link global warming to these effects often remain unknown [ 7- 9].

Acoustic signals are widely used by animals for communication, orientation and foraging [ 10, 11]. The active space within which a receiver can detect and recognize a sender's signal depends both on the sound signal per se and the process of sound transmission [ 11- 13]. Many animal sounds are adapted to the acoustic properties of the animal's habitat in a way that minimizes sound transmission loss [ 12- 14]. Consequently, changing acoustic properties of habitats can change animals' fitness. Sound attenuation is a direct function of ambient temperature. Therefore, global warming has the potential to change the acoustic properties of animal habitats and to directly impact the sensory ecology of sound-mediated behaviours.

Bats (Chiroptera) are the second most species-rich order of mammals and occur from the tropics to the polar circle on all continents except Antarctica. Like other animals, bats are vulnerable to climate change [ 15], with predicted and observed effects on their biogeographic patterns and reproductive success [ 8, 16- 18]. Some of these changes can be attributed to direct effects of rising temperature on temperature-dependent processes, including hibernation and reproduction [ 19]; other indirect effects might be mediated by habitat degradation, changes in prey abundance and extreme weather events [ 15, 19]. Here, we consider another mechanism based on the physics of sound transmission, which has the potential to directly affect the perception in the roughly 1000 bat species that rely on ultrasonic echolocation for navigation and/or foraging.

Echolocating bats emit ultrasonic calls, which spread through the ambient air and reflect off surrounding objects. Echolocation is limited by the maximum distance over which audible echoes return, which depends on the atmospheric attenuation of sound in air, which, in turn, is a nonlinear function of both call frequency, air temperature and humidity [ 20- 22]. If changing ambient temperature increases atmospheric attenuation, then echolocating bats will be subjected to reduced maximum prey detection distances and reduced prey detection volumes ( figure 1 a).

Unlike the daily and seasonal fluctuation of temperature, global warming is characterized by an average rise of ambient air temperature [ 1]. Thus, global warming will shift the present-day temperature distribution to higher values. Here, our aim was to use present-day climate data and the predicted temperature rise of the twenty-first century to examine the effect of the shifted temperature distribution on the prey detection ability of echolocating bats. We first obtained the present-day distribution of weather conditions and predicted the future distribution based on models of global warming. We then operationalized prey detection ability as prey detection volume, a physically clearly defined parameter which describes the maximum volume that a bat can sample when searching for prey and which is a function of the temperature-dependent sound attenuation. We used the weather data to calculate the temperature-dependent change of prey detection volume for the entire range of bat echolocation call frequencies and for climate zones around the globe.

2. Material and methods

2.1. Present-day and future distribution of weather parameters

We retrieved the distribution of present-day air temperature and relative humidity for a typical temperate (Germany) and tropical (Malaysia) biome from Weather Online UK ( www.weatheronline.co.uk; figure 1 b). Many bat species, especially those foraging in open and edge air space, concentrate their foraging activities in the first hours after sunset to take advantage of the higher prey abundance [ 23- 27]. To represent the weather conditions during the main activity period of bats, we thus only used data within ca 1-2 h after sunset (obtained from www.timeanddate.com, temporal resolution of data: 1 h) and from May to September for Germany. For Germany, weather data originated from 2009 to 2011 (September: 21:00; May and August: 22:00; June and July: 23:00), totalling 85 420 data points (measured by 26-218 weather stations per day, median = 204). For Malaysia, weather data originated from 20:00 for all months of 2009-2011, totalling 17 443 data points measured by one to 20 stations per day (median = 16). Air pressure was set to 101 325 Pa.

To obtain the future distribution of weather parameters, we used the present-day distribution and predictions for global warming [ 1]. Global surface temperature is predicted to rise by 1.1-2.9°C under the lowest CO ₂ emission scenario (B1, best estimate: 1.8°C) and by 2.4-6.4°C under the highest CO ₂ emission scenario (A1FI, best estimate: 4°C) during the twenty-first century [ 1]. To represent both scenarios, we increased each temperature data point in the distribution by 2°C and 4°C ( figure 1 c). We kept the values for relative humidity and air pressure constant. Relative humidity is believed to be stable in the process of global warming owing to water vapour feedback from intensified water cycles [ 28, 29]. Measured and predicted change of air pressure in response to global warming is at the most in the order of −10 to 7 hPa [ 30], resulting in negligible change of atmospheric attenuation of at most ±1.5%, yet mostly markedly less than 1%.

2.2. Physical model of maximum prey detection distance

The prey detection ability of bats is limited by the maximum distance d over which they can detect prey echoes ( figure 1 a). d is determined by the transmission loss of sound in air (loss due to spherical spreading and atmospheric attenuation) and by bat- and prey-specific parameters (hearing threshold, call intensity, target strength), as given by the sonar equation [ 31]:

where DT is bat detection threshold for echoes (dB sound pressure level, SPL), SL is source level (in dB SPL at 1 m in front of the bat), TS is target strength (the sound level reflected off a target measured at 1 m distance, in dB relative to the impinging sound), TLS and TLA are transmission losses owing to spherical spreading and atmospheric attenuation of sound, respectively, both on the way from the bat to the prey and back (dB).

Detection threshold, source level and target strength are independent of weather conditions. We thus combined them into the variable MTL, which is the maximum transmission loss tolerable by the bat at detection threshold:

Commonly used values of the echo detection threshold DT are 0 dB SPL, which is close to the standard mammalian hearing threshold under quiet conditions, and 20 dB SPL to account for noise [ 32- 35]. Source level (SL) for aerial-hawking bats varies between 110 and 137 dB SPL at 10 cm in front of the bat [ 33- 37], corresponding to ca 90-120 dB SPL at 1 m distance. TS ranges from −70 to −30 dB for smallest to largest prey at 1 m distance [ 38]. Thus, MTL can assume values between 0 and −90 dB. For our model, we selected two exemplary, conservative values around the median MTL of −20 and −60 dB.

Both TLS and TLA can be computed from the distance that the sound travels, d. TLS, the transmission loss owing to spherical spreading, is defined as:

where d ref is the reference distance to the sound source. d ref is required, because sound pressure cannot be measured at the source itself. Commonly used values are 10 cm or 1 m, yet the actual value does not affect our calculations as long as it is kept constant.

TLA, the transmission loss owing to atmospheric attenutation, additionally depends on the atmospheric attenuation coefficient α and is defined as:

The atmospheric attenuation coefficient α is a nonlinear function of call frequency, air pressure, temperature and relative humidity [ 20]. Changing weather conditions will thus change the atmospheric attenuation of emitted call and reflected echo, and thus also the maximum distance over which bats can detect echoes. α functionally couples the maximum prey detection distance to bat species (call frequency), climate zone (weather conditions) and global warming. We estimated α based on the international standard ISO 9613 [ 39], which has an error of less than 10% for almost the entire range of tested environmental conditions (see electronic supplementary material, figure S1). Because we estimated prey detection volumes before and after global warming of +2°C and +4°C, i.e. for two very similar climatic conditions, the error of the change in prey detection volume studied here (equation (2.5)) will be much smaller than the similar errors of the absolute prey detection volumes, which almost cancel each other out.

Because the sonar equation cannot be solved analytically for d, we used the iterative Newton method to compute d for all frequency, temperature and relative humidity values.

2.3. Physical model of the change of maximum prey detection volume

We operationalized 'prey detection ability' of bats as the prey detection volume, the total air space from within which a bat can hear the echo of a prey item ( figure 1 a). The change in prey detection volume ( Δ V) is the difference between the detection volume before and after global warming ( V - V ₀), normalized to the initial detection volume ( V ₀):

We modelled the change of prey detection volume Δ V separately for perch-hunting (stationary) and aerial-hawking (flying) bats ( figure 1 a). Perch-hunting bats are stationary and cannot detect prey beyond the maximum detection distance of a single call. We approximated their prey detection volume by a spherical sector with the bat at the sphere's centre and the sector's opening angle defined by the width of the sonar beam [ 40]:

where d is maximum prey detection distance of bats (=radius of the sphere), θ is full width of sonar beam (=sector's opening angle). The change in detection volume ( Δ V; equation (2.5)) is independent of the sonar beam width and can be directly calculated from the detection distance:

In contrast to stationary bats, flying bats might detect prey beyond the detection distance of one call with the next call emitted closer to the prey. We thus estimated the volume covered by one given call, without the volume covered by the following call ( V, yellow dotted line, figure 1 a). We defined this volume V as the volume of a spherical sector ( V sector, equation (2.6)), added a cylindrical detection volume owing to the forward displacement of the bat during call emission ( V cylinder) and subtracted that part of V sector, which will also be covered by the next call ( V overlap):

As before, we then used equation (2.5) to calculate Δ V, which depends on flight speed, call interval, call duration and sonar beam width. Across the natural range of these parameters, the variation of Δ V is small (differences = −0.5 to 2.1 percentage points) for changes of flight speed, call interval and call duration, and almost non-existent for changes of beam angle (differences < ±0.01 percentage point). We thus used common values for an aerial-hawking bat in search flight of 6 m s −1 flight speed, 100 ms call interval, 10 ms call duration and 45° full sonar beam width.

A typical bat community is composed of species with different and species-specific call frequencies, which together cover a broad frequency range [ 33, 41]. We calculated Δ V for the typical range of call frequencies of insectivorous bats from 10 to 150 kHz, for maximally tolerable sound transmission losses (MTL) of −20 and −60 dB, and for every data point of the present-day and future (+2°C and +4°C) weather conditions of the temperate (Germany) and tropical (Malaysia) biome. Per call frequency, MTL, temperature rise and biome, we then averaged the Δ V-values calculated for all single weather data points to obtain the mean Δ V, i.e. the average change in prey detection ability of echolocating bats after an increase of the present-day temperature distribution by +2°C and +4°C. Our model is based on more than 100 000 weather data points describing the distribution of weather conditions in temperate and tropical climate zones. This approach maintains the daily and seasonal fluctuation of temperature, which persists in the temperature distribution shifted by +2°C and +4°C. As this detailed data, however, will not always be available, we also calculated a model based only on mean values of temperature and humidity and compared it with our full model (see the electronic supplementary material, figure S2).

2.4. Potential vocal compensation for reduced prey detection volume

Changing temperature alters the atmospheric attenuation coefficient α, thus changing the atmospheric attenuation of call and echo and consequently prey detection distance and volume. If prey detection volume is reduced, then bats might compensate for this effect by changing call parameters that influence the atmospheric attenuation (equation (2.4)) or the sonar equation (equation (2.1)). Specifically, bats could (i) decrease call frequency to counterbalance the effect of rising temperature on α, thus keeping α overall constant, or (ii) increase source level to compensate for the increased atmospheric attenuation of sound after global warming. Calculations were performed using the mean weather conditions of both climate zones before (temperate: 14.7°C, 78%; tropical: 27.1°C, 85%) and after (+2°C and +4°C) global warming and only for those call frequencies at which bats would suffer a reduced prey detection volume. For every call frequency, we used the estimate of α [ 39] and the iterative Newton method to calculate the post-warming call frequency at which α resumed its pre-warming value despite the increased temperature. The required change in call frequency, Δ f, is the difference between the original and the post-warming call frequency. The required change in source level, ΔSL, was calculated for every call frequency from equation (2.2), combined with the equations of TLS and TLA (equations (2.3) and (2.4)). Inserting the post-warming α and the desired unchanged pre-warming detection distance into the equations yields the required post-warming MTL. Δ SL is the difference between pre- and post-warming MTL, because no other components of MTL have changed.

2.5. Change of prey detection volume in climate zones around the globe

We used the same physical model of prey detection volume to calculate the potential impact of global warming on bat communities from any climatic condition around the globe. For all combinations of temperature (0-35°C), relative humidity (0-100%) and bat call frequencies (10-150 kHz), we calculated Δ V for global warming of +2°C and +4°C (see electronic supplementary material, figure S3 for exemplary results). To summarize these data and to describe the severity of the effect of global warming on bat communities in different climatic conditions, we extracted four parameters for each temperature-humidity condition (cf. inset in the electronic supplementary material, figure S4). (i) Crossover frequency f ₀: the frequency at which the prey detection volume will not change. (ii) Overall magnitude: the difference between the maximum and minimum change in prey detection volume as a measure of the overall effect size across the full range of call frequencies. It describes the overall effect between the most advantaged and disadvantaged bat species, i.e. the magnitude of change within a community of potentially interacting species. Finally, we calculated the derivative of the change in prey detection volume with respect to frequency. This yields the slope of the curves depicted in figure 2 at each frequency and is a measure of how much the effect of global warming differs between close-by call frequencies (in contrast to the previously calculated overall effect size). We computed the (iii) maximum, and (iv) the mean of these absolute slopes and expressed them as percentage point difference in detection volume per 10 kHz call frequency. The maximum absolute slope describes the most extreme effect on two bats differing in call frequency by 10 kHz, whereas the mean absolute slope describes the average effect across the whole frequency range on any two bats differing in call frequency by 10 kHz.

Note that these different measures did not qualitatively disagree on the relative impact of global warming on bat communities in different climates (see electronic supplementary material, figure S4) and only slightly differed in the exact climatic values for which the minimum and maximum impact on bat communities will occur.

3. Results

3.1. Change of maximum prey detection volume in temperate and tropical bats

All models showed that global warming will alter the maximum prey detection volume of echolocating bats in a species- and climate-dependent manner ( figure 2 ). We found a consistent pattern that across bat species with different call frequencies, rising temperature will lead to increased detection volume at lower frequencies and reduced detection volume at higher frequencies. At medium frequencies, a crossover frequency f ₀ exists at which the maximum detection volume will stay constant. Depending on call frequency, global warming will thus directly enhance the prey detection ability of some species, whereas others will have a reduced prey detection volume. The effect of rising temperature on prey detection volume will be larger for the +4°C than for the +2°C temperature rise ( figure 2 , red and blue lines), for situations with higher tolerable transmission losses ( figure 2 , expressed as MTL, solid and dashed lines), and for perch-hunting than for aerial-hawking bats ( figure 2 a,b versus c,d).

Furthermore, species-specific effects, which are determined by the sound frequency-dependence of atmospheric attenuation, will be mediated in a biome-specific way depending on the local climatic conditions ( figure 2 a,c versus b,d). In particular, the models predict that both the crossover frequency f ₀ between detection volume gain at lower call frequencies and detection volume loss at higher call frequencies, and the overall impact of rising temperature will be affected by the local climate. The crossover frequency will be around 35 kHz for temperate and around 95 kHz for tropical bat communities. The impact of rising temperature will be stronger on temperate bat communities than on tropical ones. In temperate climate, prey detection volume will increase by up to 14% or decrease by up to 21% (perch-hunting bats, +4°C, MTL = −60 dB). In tropical climates, prey detection volume will increase and decrease by up to 16% and 10%, respectively.

We used the difference in prey detection volume change as a simplified measure for the differential impact on sympatric species in a given climate. We found an overall magnitude of 35 percentage points difference between the most benefiting and the most disadvantaged bat species in the temperate bat community, and a smaller overall magnitude of 18 percentage points in the tropical bat community (see §3.3 and the electronic supplementary material, figure S3 for additional measures comparing community effects).

3.2. Potential vocal compensation for reduced prey detection volume

Echolocating bats might be able to compensate for a reduced detection volume either by lowering call frequency (i.e. lowering atmospheric attenuation; figure 3 a) or increasing call intensity (i.e. counteracting the increased atmospheric attenuation; figure 3 b), thus keeping the detection volume constant at present-day values. For a 4°C temperature rise and an MTL of −60 dB, temperate bat species would be required to reduce call frequency by up to 14 kHz or increase call intensity by up to 4.9 dB (almost a doubling of amplitude), compared with 7 kHz and 2.4 dB for tropical bats ( figure 3 ).

3.3. Change of prey detection volume in climate zones around the globe

To go beyond our two exemplary bat communities from temperate and tropical climates, we quantified the effects of rising temperature on the prey detection volume of echolocating bats for the entire range of climatic conditions found in bat habitats around the globe. We found a consistent pattern along the gradients of temperature (0-35°C) and relative humidity (0-100%; figure 4 and the electronic supplementary material, figures S3 and S4). The crossover call frequency f ₀, i.e. the frequency with no change in prey detection volume, is predicted to increase from 10 to 150 kHz with warmer and more humid climates, with little difference between the two emission scenarios of +2°C and +4°C global warming ( figure 4 a,b). By contrast, the overall magnitude, i.e. the difference in the change of prey detection volume between the most benefiting and the most disadvantaged sympatric species will increase with the amount of global warming to up to 20 and 40 percentage points for the two scenarios, respectively (perch-hunting bats, MTL = −60 dB; figure 4 c,d). Likewise, the differential effect on sympatric species reaches up to 16 and 30 percentage point differences in change of prey detection volume for species differing by 10 kHz in call frequency (electronic supplementary material, figure S4 e, f). The differential effect on bat species ( figure 4 and electronic supplementary material, figure S4) is smallest in tropical regions and is strongest for biomes along a gradient of climatic conditions from low-temperature-high-humidity (cold to temperate regions) to high-temperature-low-humidity (arid regions).

4. Discussion

4.1. Direct impact of climate change on individuals and species

Rising temperature can impact animals via multiple mechanisms, e.g. directly as an abiotic effect on temperature-dependent physiological processes and indirectly through changes in the biotic environment, caused by the differential effects on participants in interspecific interactions [ 15]. Using present-day climate data, predicted temperature rises and a physical model of sound transmission, we show that global warming will lead to both positive and negative changes in the prey detection volume of echolocating bats. Furthermore, we quantitatively show how these changes depend on the species' call frequency and the local climatic conditions. Thereby, we found that global warming will directly act on the prey detection of echolocating bats. This is the first example of a mechanism by which global warming can directly act on the sensory perception of animals.

Generally, bats using lower call frequencies will have enlarged prey detection volumes, whereas the detection volumes of species calling above a crossover frequency will decrease. Even without competitive interactions between species (we discuss potential competitive interactions in §4.3), this can alter community structure. Bats with calls below the crossover frequency will benefit from climate change, whereas individuals using higher call frequencies will experience foraging costs, leading to differential changes in foraging and reproductive success.

On a global scale, we found the strongest differential effect of global warming on prey detection volume for sympatric bats living along a gradient from cold-and-wet to hot-and-dry regions. Besides the larger effect magnitude under these climatic conditions than in the tropics, also the crossover frequency is lower and splits the range of call frequencies of aerial-hawking bats in two ( figure 2 ). Therefore, our model predicts that bat communities in cold to temperate and arid regions will experience the largest effects on community composition, whereas communities in tropical climates will be less affected. In the natural world, most bat species that search for prey in open and edge airspace-and for these, detection volume likely matters the most-use low call frequencies well below 100 kHz [ 41, 42]. Most tropical species of this group are predicted to gain prey detection volume ( figure 2 ); however, the differences in gain may still alter community composition. By contrast, in temperate and arid climates, this shift is predicted to be stronger, because the crossover frequency falls within the frequency range of aerial-hawking bats. In Europe, for example, four to five aerial-hawking species call above the crossover frequency [ 41] and are predicted to lose prey detection ability, whereas about nine species call around and below f ₀ [ 41] and will have constant or increased detection ability. Even if the disadvantaged species were fully able to compensate for the reduced detection volume, then the enlarged detection volume of the benefiting species might give them an advantage over the sympatric species.

The accuracy of our quantitative estimates of the change in prey detection volume is dependent on the assumption that bats use their complete detection volume while foraging. This assumption is strongly supported by the fact that aerial-hawking bats use calls of high intensity [ 33, 34] to maximize detection range, and between-call intervals that are long enough that echoes from the edge of the detection volume return before the next call is emitted [ 33]. Thus, bats listen for echoes from the entire prey detection volume.

Increased prey detection volume will lead to increased foraging efficiency under the assumption that prey density stays the same. Currently, there is no clear evidence whether insect abundance will increase or decrease [ 43], because different insect taxa will respond differently to climate change [ 43, 44]. For example, climate change can cause extinction, range shifts and declining abundance of many insects, including beetles, butterflies and moths [ 45- 48], whereas the abundance of herbivorous insect pests is predicted to increase [ 49]. Therefore, future insect prey availability may differ for different predators depending on the specific response of their prey species to climate change. Our model thus only describes the physical limits of bats' prey detection ability; their future foraging efficiency will be influenced by the combination of their reduced or increased detection ability and the specifically changed prey availability. However, even if prey density does not stay constant, but changes in the same direction for several species, then the differential change in prey detection volume will cause differences in foraging success between species.

4.2. Potential compensation for reduced prey detection volume

While sensory systems are capable of adapting to short- and long-term changes [ 50], and bats adjust call frequency and intensity on a short-term basis to the present task and habitat [ 37, 42], it is unknown whether and to what extent they are able to behaviourally compensate for long-term changes of sound transmission loss. Caused by the existing variation in temperature, bats might already have mechanisms to adapt their (vocal) behaviour to variable atmospheric attenuation, or to manage the costs of variable prey detection ability. However, global warming acts in addition to the existing natural variation. Although the shift in temperature caused by global warming is smaller than the natural daily, seasonal and spatial variation ( figure 1 c), it will exert extra pressure on any already existing mechanism to deal with varying prey detection abilities, likely causing additional costs. By contrast, species with constant or increased detection volume will not experience these additional costs.

Ecological, morphological and energetic constraints may limit the potential for vocal compensation. Because echolocation calls are adapted to the echo-acoustic requirements of a species' ecological niche at both broad (e.g. open versus cluttered foraging space; [ 42]) and fine scale (e.g. niche differentiation within the same habitat type; [ 51]), foraging ecology may prevent any changes in call parameters. For example, lowering call frequency is a two-sided sword. It increases detection volume, but at the same time reduces echo intensity of small prey and thus their detection distance and perceived availability [ 41]. For constant-frequency bat species (Rhinolophidae, Hipposideridae, Pteronotus parnellii), the auditory processing is morphologically and neuronally precisely tuned to a narrow frequency range [ 52], rendering behavioural plasticity in call frequency futile. Even though echolocation is normally not energetically expensive during flight [ 53], the around twofold increase in call amplitude required for the compensation ( figure 3 ) might cause substantial energetic costs [ 54] or fatigue of the vocal apparatus [ 55], and even more so for stationary bats [ 56- 58]. Over longer timescales, by contrast, bat species might adapt to the local climatic conditions. Both in different species of the genus Rhinolophus [ 59] and in some geographically disjunctive populations of a single species [ 60, 61], call frequency was correlated to local precipitation levels, suggesting an evolutionary adaptation of call frequency to average local sound attenuation. Despite daily and seasonal fluctuation of ambient temperature, it is thus conjecturable that reduced average prey detection ability caused by global warming will shift call frequency and intensity in the directions predicted by figure 3 . However, because the current climate change is very rapid due to its anthropogenic causes and bats reproduce slowly and have long generation times, the time available might not suffice for an evolutionary change.

Bats might use further behavioural strategies, in addition to vocal compensation, to compensate for reduced foraging efficiency. Individuals could extend periods of foraging or actively select areas with higher perceived prey density [ 62] or cooler climate (e.g. higher latitudes and altitudes). In the latter case, the temperature-dependence of atmospheric sound attenuation could be one of several mechanisms underlying the observed shift of bat distribution ranges [ 15]. On the other hand, these behavioural strategies might incur additional costs, as for the vocal compensation. Increasing periods of foraging will require additional energy and time spent on foraging, whereas areas with higher prey density or cooler climate might be limited or less suitable for other reasons. The ability to compensate will likely vary with the species, its biotic and abiotic interactions and how global warming will influence these interactions.

To summarize, bats may compensate for the reduced foraging efficiency caused by global warming, but this compensation will likely incur costs. By contrast, species with constant or increased detection volume will not experience these additional costs and thus again have an advantage over the negatively affected species.

4.3. Indirect effect of global warming through changed interspecific interactions

So far, we have discussed the direct impact of global warming on the prey detection ability of individuals and have shown that it will affect sympatric species differentially (the difference reaching up to 40% in some exemplary cases; figure 4 c,d) and will thereby potentially shift community balance. These effects can be further potentiated by changes in interspecific interactions, particularly competition among sympatric bat species and interactions between bats and their eared insect prey.

If species, whose foraging efficiency will be reduced by climate change, are competing for the same food resources with species whose prey detection volume will increase, then the latter species may outcompete the former. The benefiting species will dwell and may potentially spread to new habitats, whereas the disadvantaged species may be excluded from these habitats. Competition for food among sympatric species is hard to prove in nature; however, in bats, there is indirect evidence that competition affects community composition [ 51, 63]. Changes in competitive ability of sympatric species owing to anthropogenically altered habitats destabilizes present-day communities and alters relative species abundances, as suggested for European bat species [ 63] and many other animal and plant species [ 64].

Temperature-dependent changes in atmospheric attenuation can also influence the predator-prey interactions between bats and insects with bat-detecting ears [ 65]. Given constant bat call intensity and frequency, global warming will change detection distances for calls (by insects) and echoes (by bats). The maximum detection distance is shortened more severely for bats than for eared insects [ 35], because bat calls have suffered only a one-way transmission loss, when they reach the insect, whereas echoes reaching the bat have suffered a two-way transmission loss. As a result, the ecological and coevolutionary balance between predators and prey can change.

Biotic interactions are thus an important mechanism underlying the ecological responses of species to climate change [ 7], including changes in the structure and biodiversity of present-day communities.

5. Conclusion

Global warming affects the energetics [ 8] and biogeography [ 15] of bats and also the abundance of their insect prey [ 49], often via unknown mechanisms [ 7- 9]. Because echolocating bats largely perceive their surroundings by ultrasound travelling through air, the temperature-dependence of atmospheric attenuation is a mechanism that functionally links global warming to their sensory capabilities. This mechanism will likely also influence the acoustic behaviour of species other than bats. For example, the height of songbird posts has increased in recent years as an adaptation to altered local climatic conditions [ 66]. In summary, global warming can affect the prey detection ability of the diverse predator community of echolocating bats, with potential consequences for their foraging efficiency and interspecific interactions. Ultimately, this mechanism may contribute to the observed and predicted effects of global warming on bats and may affect their community structure, distribution and biodiversity as well as those of their insect prey [ 67, 68].

Acknowledgements

We thank two anonymous reviewers for their helpful comments. This paper is dedicated to our co-author, colleague, mentor and friend Björn, who passed away during its preparation. His love of life and science will remain an inspiration to all of us. J.L., K.K., B.M.S. and H.R.G. designed the study; J.L., K.K. and H.R.G. ran model calculations, S.Z. retrieved and analysed the climate data, J.L. and H.R.G. wrote the first draft. All authors jointly discussed the results, commented on the manuscript and H.R.G., K.K. and J.L. revised it.

Funding statement

This study was supported by the China Scholarship Council (J.L.), the Max Planck Society (B.M.S.) and the European Research Council (B.M.S., H.R.G.). J.L. is also supported by the International Max Planck Research School (IMPRS) for Organismal Biology.

References

11. Bradbury JW, Vehrencamp SL. 2011. Principles of animal communication, pp. 65-111. Sunderland, MA: Sinauer Associates. [ Google Scholar]

39. International Organization for Standardization. 1993. Acoustics - attenuation of sound during propagation outdoors, ISO 9613. Genève, Switzerland: International Organisation for Standardization. [ Google Scholar]

40. Harris JW, Stocker H. 1998. Handbook of mathematics and computational science. New York, NY: Springer. [ Google Scholar]

63. Arlettaz R, Godat S, Meyer H. 2000. Competition for food by expanding pipistrelle bat populations ([ Pipistrellus pipistrellus) might contribute to the decline of lesser horseshoe bats ( Rhinolophus hipposideros). Biol. Conserv. 93, 55-60. ( 10.1016/S0006-3207(99)00112-3) [ CrossRef] Google Scholar]

Articles from Journal of the Royal Society Interface are provided here courtesy of The Royal Society

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Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats

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Climate change impacts the biogeography and phenology of plants and animals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum ...

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The use of Echolocation in Blind Individuals 

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The use of Echolocation in Blind Individuals 

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Inspired through the genius use of echolocation in bats and dolphins, numerous humans have started to learn it as well. Two men named Daniel Kiss and Juan Ruiz were both named human bats, being extremely skilled at echolocation. When animals use echolocation they emit bursts of sounds and listen to the echos that then bounce back, allowing them to perceive their environment. Similarly, when people use echolocation they make audible emissions such as, mouth clicks, finger snaps, whistling, or footsteps, all of which are in the audible spectrum compared to ultrasound emission that bats and dolphins use. The people who chose to learn how to echolocate are primarily blind, with studies showing 83% of blind people have reported an improved well being after learning how to echolocate with other benefits such as mobility and independence. In saying that, one does not have to be bind to learn how to echolocate with studies showing neither age nor blindness was a limiting factor. Looking further into the brain process behind this, in normal sighted people the cortical areas are activated through vision which is the same area activated as blind individuals echolocate. Overall, the benefits of echolocation in regards to giving blind people an increased well-being are phenomenal, though everyone is capable of learning this skill.

Question: What are the most effective techniques for teaching echolocation, how do different methods affect ones ability to echolocate?

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Keep up to date with news and views on current physiological issues with our quarterly Members’ magazine Physiology News.

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Human Hearing compared to echolocation in marine mammals

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Human Hearing compared to echolocation in marine mammals

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For most shallow depth, sea mammals such as dolphins and orcas will not feel drastic pressure changes even if they dive deeper as in deeper depths pressure increases resulting in faster sound waves due to the increased compactness of molecules allowing for faster transmission. However, as temperature decreases to become cooler it decreases the speed of sound and can hinder the dolphin's sense to detect prey or predators as sound waves deflecting off objects & organisms arrives back slower. This mainly only affects larger sea mammals such as whales who delve in deeper depths as they use the slow moving nature of the sound waves at cooler temperatures to send long distance messages.

Echolocation works by the organism emitting its own sound waves, which will deflect off any object back towards the organism, informing it about the shape and location of the object.

Will, human hearing utilizes incoming vibrations that cause movement in different regions of the cochlea duct depending on the frequency, which are transmitted into neural signals to provide the brain with the distance and direction of the incoming sound.

Echo locating organisms usually have almost no existing ear holes and really larger ossicles of the ear to ensure efficiency of sound waves entering the ear & detection of even subtle water sounds which is vital to detect prey & predator, as well as increasing marine mammals aerodynamics to increase speed

Humans have really prominent ear openings to collect and funnel as many vibrations into the ear

Dolphins have greater hair cell density to interpret the smaller frequency sounds of subtle water movements

Dolphins have finely tuned hair cells that detect different frequency than that of human hair cells

Other differences not so thoroughly discussed are differences in the shape, size, arrangement of the cochlea and the cochlea duct that better suits marine life for echolocation and underwater navigation.

Lastly, marine mammals use echolocation for hunting and navigation in the water where vision is very limited and not reliable resulting in an evolutionary pressure in the evolution towards a more complex & advanced hearing system that relies on echolocation

Humans do not mainly rely on hearing for navigation and rather for communication, not as complex as dolphin because eyes are used to navigate their space.

Q: How do marine mammals adapt their echolocation techniques to different underwater environments with varying terrain and organisms with countermeasures?

Links:

1. https://pubs.aip.org/asa/jasa/article/142/4/EL381/853330/A-simulation-of-temperature-influence-on

2.https://cimi.org/blog/sound-in-water/

3. https://school.eb.com/levels/high/article/sound-reception/109525

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Can help with mobility independence and well being for peoples who are partially sighted or blind

Use echolocation and use it to understand how the human brain adapts to learning new skills

Motion capture to see how it could be relating to the body movement

Using echolocation to better understand the human brain and cognition

Works well with other methods, using guide dogs or a long cane

Echolocation can support walking in a similar way to vision

Study found that “people who are blind and who have experience using echolocation walk just as fast as people using vision”

Could be used to help build a better future

Echolocation could be a skill used for people who are blind

In what ways could echolocation be used to help understand body movements, could this further be used to help develop aids for the blind or partially sighted.

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Keep up to date with news and views on current physiological issues with our quarterly Members’ magazine Physiology News.

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Echolocation: Blind people have the potential to use their 'inner bat' to locate objects, study finds

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Echolocation: Blind people have the potential to use their 'inner bat' to locate objects, study finds

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Hearing, and particularity the hearing of echoes could help blind people with spatial awareness and navigation

Blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object

Could be used to improve the independence and quality of life of people with visual impairments

Results showed that “both sighted and blind people with good hearing, even if completely inexperienced with echolocation, showed the potential to use echoes to tell where objects are”

Researchers also found that “hearing high - frequency sounds (above 2kHz) is required for good performance, and so common forms or hearing impairment will probably cause major problems.

How can programs be designed to enhance echolocation skills in individuals, how could it be used to develop better training.

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New research from the University of Southampton has shown that blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object.

The study, which is published in the journal Hearing Research, examined how hearing, and particularly the hearing of echoes, could help blind people with spatial awareness and navigation. The study also examined the possible effects of hearing impairment and how to optimise echolocation ability in order to help improve the independence and quality of life of people with visual impairments.

Researchers from the University of Southampton's Institute of Sound and Vibration Research (ISVR) and University of Cyprus conducted a series of experiments with sighted and blind human listeners, using a 'virtual auditory space' technique, to investigate the effects of the distance and orientation of a reflective object on ability to identify the right-versus-left position of the object. They used sounds with different bandwidths and durations (from 10-400 milliseconds) as well as various audio manipulations to investigate which aspects of the sounds were important. The virtual auditory space, which was created in ISVR's anechoic chamber, allowed researchers to remove positional clues unrelated to echoes, such as footsteps and the placement of an object, and to manipulate the sounds in ways that wouldn't be possible otherwise (e.g. get rid of the emission and present the echo only).

Dr Daniel Rowan, Lecturer in Audiology in ISVR and lead author of the study, says: "We wanted to determine unambiguously whether blind people, and perhaps even sighted people, can use echoes from an object to determine roughly where the object is located. We also wanted to figure out what factors facilitate and restrict people's abilities to use echoes for this purpose in order to know how to enhance ability in the real world."

The results showed that both sighted and blind people with good hearing, even if completely inexperienced with echolocation, showed the potential to use echoes to tell where objects are. The researchers also found that hearing high-frequency sounds (above 2 kHz) is required for good performance, and so common forms of hearing impairment will probably cause major problems.

Dr Daniel Rowan adds: "Some people are better at this than others, and being blind doesn't automatically confer good echolocation ability, though we don't yet know why. Nevertheless, ability probably gets even better with extensive experience and feedback.

"We also found that our ability to use echoes to locate an object gets rapidly worse with increasing distance from the object, especially when the object is not directly facing us. While our experiments purposely removed any influence of head movement, doing so might help extend ability to farther distances. Furthermore, some echo-producing sounds are better for determining where an object is than others, and the best sounds for locating an object probably aren't the same as for detecting the object or determining what, and how far away, the object is."

The knowledge gained from this study will help researchers to develop training programmes and assistive devices for blind people and sighted people in low-vision situations. The team is also extending their research to investigate finding of objects in three-dimensional space and why some blind people seem to be able to outperform others, including sighted people.

The research was partly funded by a Research Council UK Basic Technology Programme grant to the Bio-Inspired Acoustical Systems project and Engineering and Physical Sciences Research Council (EPSRC) Vacation Bursaries.

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eye care; hearing loss; disability; perception; hearing impairment; behavior; extreme survival; biology; animal learning and intelligence

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Echolocation: Blind people have the potential to use their 'inner bat' to locate objects, study finds

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New research shows that blind and visually impaired people have the potential to use echolocation, similar to that used by bats and dolphins, to determine the location of an object. The study examined how hearing, and particularly the hearing of echoes, could help blind people with spatial awareness and navigation.

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Echolocation usage and benefits for technology in society. 

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Echolocation usage and benefits for technology in society. 

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How does echolocation work on humans?

- Echolocation can be learned as a skill. Experts have found that the human brain has areas that are made to process echoes. An estimated average of 20% to 30% of blind people learn how to echolocate at some point in their lives.

- Many animals have their own sound that they choose to echolocate with, humans also can choose a specific sound that they echolocate with. Finger snaps, humming, and mouth clicks are some of the most commonly used noises for humans to echolocate.

How can humans benefit from echolocation?

Studies show echolocation improves special awareness which results in better mobility and better understanding of the environment.

After learning how to echolocate, many people said that they feel like they have a new sense, which improves their overall well being.

Echolocation is a major skill for people to learn. Surprisingly, learning how to echolocate even if you do not need to, increases salaries all over the world, employees would be able to communicate and interact with clients, and it has many more benefits.

How is Echolocation used in Technology?

Echolocation is not only restricted to dolphins. It is used in many ways by humans in technology. It is accommodated in sonar, which sends pings inside the water and listens for the echoes. The innovation in sonar developed into radar, using echolocation.

One of the major innovations in echolocation, is the utilization of lasers, presently recognized as Lidar. Lidar is now used by archaeologists to investigate layers of the planet.

Lidar was used to assist scientists to travel around 2,000km in a short span of time.

A similar device to Lidar called phased-array, is also very beneficial. It is able to broadcast radio-waves in a given direction.

Lidar cannot scan signs because theyr’e flat, it can be quickly interrupted by restricted visibilities.

Overall, scientists still have much innovation, testing and research before Lidar will be used to operate autonomous-vehicles. There are yet many difficulties that Lidar can yet be the solution for.

Links: https://www.webmd.com/eye-health/how-blind-people-can-use-echolocation

https://gisresources.com/echolocation-technological-developments/

Next Question: How can advancements and innovation in technology further improve human echolocation abilities? What potential applications can arise from these developments?

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Ocean noise pollution is a major setback that marine mammals face now that affects their ability to undergo effective echolocation, vital to their survival and communication.

Ocean noise pollution is caused by human made sounds that in most water vessels are required to travel long distances and at low frequencies.

These noises contribute to stranding, beaching, abnormal behaviors and changes in feeding patterns.

Orcas are especially affected by noise pollution, as they hunt by utilizing high frequency sounds that echo off of any prey into their lower jaw & then interpreted by their brain to understand where the prey is.

Noise pollution masks these echoes, resulting in misinterpretation or even miscommunications between pods of orcas that could result in division, terrtorialness, and increased aggression.

This noise pollution affect was further researched, showed that noise pollution had very little effect on adult killer whale echolocation compared to their offsprings, suggesting a difference in strength of sound waves. This is also due to the directional hearing ability of the killer whale.

Masking can have effect on the behavioral aspects of a marine mammal such as difficulty in mating, habituation, presences of dependent offspring, determining whether an object is stationary or moving, promixity to shoreline, etc.

Q: How can developers of underwater technologies be mindful of ocean noise pollution to minimize the effects it has on marine mammals? Consider multiple factors with underwater sound travel?

Links:

1. Understanding Ocean Noise

2. Effects of Noise on Marine Mammals

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The Impact of Climate Change on Echolocating Bats 

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The Impact of Climate Change on Echolocating Bats 

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Bats echolocate through producing high frequency sounds, ultrasonic waves, and comparing the sounds they emit to the returning echoes. Through echolocation, bats are able to locate and forge prey, navigate their environment and the obstacles within. As sound waves travel through the atmosphere, the amplitude of the sound decreases, known as sound attenuation. Through higher temperature and increase humidity, the ultrasound waves that the bats produce end up losing clarity and effectiveness. Further effecting prey detection, navigation and communication suffers. A study has showed that as much as a 4 degree celsius increase greatly impacts echolocation, even more in tropical biomes. Due to climate change, bats with low-frequency calls will improve prey detection and outgrow the species with high-frequency calls, leading to new foraging patterns and other ecological changes. In saying this, there are methods for bats to adapt to this change. Bats could possible decrease their call frequency or increase the intensity of calls, however, that may lead to energy exposure or vocal fatigue and reduce the maximum distance at which bats can detect prey.

Question: What further adaptations might bats undergo to mitigate the effects of climate change on their echolocation abilities, what further consequences will these have on ecology?

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A struggle to find prey: How climate change is affecting bat echolocation – NU Sci Magazine

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Imagine you lost your AirPods. Multiple “pings” are emitted from the case for you to track down. Now imagine attempting to locate the source of these pings but with noise-canceling headphones on. It would be much harder to find the AirPods with something blocking the sound from reaching you, right? Bats that use echolocation may suffer from effects similar to those of noise-canceling headphones.

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Marine mammals have evolved sophisticated echolocation techniques to adapt to diverse underwater environments, including varying terrain and organisms with countermeasures.

In fact, marine mammals such as dolphins, whales, and porpoises emit sound pulses through specialized structures called "phonic lips" and focus these sounds using a fatty organ known as the melon.

The echoes from these sounds are received through their lower jaw, specifically through an area called the "acoustic window." This setup allows them to form detailed, three-dimensional images of their surroundings.

Species like sperm whales have developed highly specialized echolocation for hunting in deep, dark waters. Their echolocation clicks are powerful and can travel long distances to detect prey like squid in the bathypelagic zone. River dolphins, which navigate and hunt in turbid river environments, rely heavily on echolocation.

Their clicks are adapted to provide high-resolution information about their immediate surroundings, helping them avoid obstacles and locate prey even in murky waters. Some marine mammals navigate under ice-covered waters where visual cues are minimal.

They use echolocation to detect openings in the ice and locate prey under the ice sheets. Increased underwater noise from human activities, such as shipping and industrial operations, can interfere with marine mammal echolocation.

These animals often adjust the frequency, intensity, and timing of their clicks to mitigate the effects of noise pollution. Some prey species have evolved to produce sounds or exhibit behaviours that reduce the effectiveness of predator echolocation.

Marine mammals adapt by altering their echolocation patterns or employing stealth tactics to approach their prey. Over millions of years, the structure of marine mammals' jaws and ears has evolved to optimize sound reception and transmission.

This includes the development of a thin mandible and specialized sinuses that help separate incoming and outgoing sounds, enabling precise echolocation even in noisy environments.

These adaptations highlight the remarkable ability of marine mammals to thrive in various underwater habitats, overcoming both natural challenges and anthropogenic impacts.

Q: How do marine mammals use echolocation to adapt their hunting strategies to avoid predation and successfully capture prey in environments with high levels of human activity and noise pollution?

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Imagine hearing with your jaw - the very same jaw used to catch and eat your food. For the about 75 species of whales, dolphins, and porpoises of the Odonotocete family, also known collectively as the toothed whales, that is their reality. A new study led by Smithsonian Peter Buck Fellow and cetacean evolution and biology expert Dr. Ellen Coombs gives us new insight into the evolutionary history of multi-purpose toothed whale jaws.

Inhabiting a variety of environments from crystal clear off-shore waters to dark, murky coastal estuaries, toothed whales are diverse, widespread, and efficient marine predators. From killer whales to bottlenose dolphins, toothed whales or Odontocetes differ from their filter-feeding cousins, the Mysticetes or baleen whales, based on - you guessed it - their teeth. But some time after the evolutionary split between these two groups, the toothed whales gained another valuable skill.

Similar to bats, all modern toothed whales possess a kind of biological sonar known as echolocation that helps them navigate environments where other senses may not allow. "It's a hunting tool," explained Coombs.

"These animals can essentially see with sound. They live in some of the deepest oceans on the planet, they're hunting in pitch black water, and they're hunting in cluttered rivers, around icy environments, as well as all over the planet. They're managing to do that with sound using echolocation."

But odontocetes don't use their ears like we do. Millions of years ago, the openings on the sides of their head all but closed up, leaving small, almost invisible holes behind the eyes. Instead of relying on traditional ear canals, toothed whales adapted to use their lower jaw to pick up noises from the water around them.

The recently published study led by Coombs focuses on the lower jaw or mandible and aims to better understand the roles that echolocation and diet play in toothed whale evolution. "We wanted to look at what's happened [during toothed whales' evolutionary history]. How they managed to evolve so many different jaw shapes and successfully conquer all of the world's oceans as apex predators," she said.

How does echolocation work in whales and dolphins? Echolocation relies on sending and receiving sounds. Toothed whales create noises by blowing air through what is known as their "phonic lips," a vibrating tissue located along their nasal passage, beneath the blowhole on the top of their head. This outgoing noise, called a "click," is focused through the fatty organ called the melon, located on their forehead. The click then travels through the water until it hits something like a fish, and its "echo" will bounce back towards the whale. Once it returns, a thin area of bone and 'fat pad' at the back of the mandible known as the "acoustic window" absorbs and transfers the returning click to the whale's inner ear. Measuring the sound and its delay time, toothed whales can discern information like the distance and even identity of the species it bounced off.

In looking at fossils and skeletons of every whale species, from modern day species to the earliest known whale ancestor Pakicetus, Coombs and her collaborators found that toothed whale evolutionary rates and diversity spiked at two points in time: first, in the early to mid Eocene (about 40-45 million years ago) when early whales (archaeocetes) first adapted to life in the water, and later in the mid-Oligocene (25-30 million years ago), a period of time in which toothed whale echolocation was refined and their diets began to specialize. "They're becoming really specialized in the type of echolocation they can use and the type of diet they can have at the same time," said Coombs. "If you're able to echolocate, you can really expand and diversify your diet." This, in turn, allowed for what the study finds to be some of the fastest rates of jaw evolution in odontocete history, as well the diversity in jaw shape and size we see today.

But all areas of toothed whale jaws did not evolve at equal rates. In fact, the back of the jaw was found to have evolved more slowly than the front. The back of the jaw, the part used for sound reception, evolved "really early in the whale evolution" when the need for underwater directional hearing first arose - but the study finds that area to stay mostly the same shape after that point. When echolocation arose in toothed whales about 39 million years ago, that jaw shape began to change again at high rates - but this time, that change was concentrated at the front of the mandible. Coombs explained,"[Toothed whales] took echolocation and ran (swam!) with it, and started to evolve to be able to eat all sorts of animals." Now able to tailor their hunting towards squid or fish or other marine mammals, the front part of the jaw used to catch prey (as opposed to the back part, used to 'hear') diversified among toothed whale species relatively quickly.

Coombs still has more questions. "The mandible itself is really thin. The back part of the mandible, called the panbone, is in some places less than a millimeter thick," she explained. If a thin mandible is necessary to echolocate, how does evolution balance hearing sensitivity and jaw strength?

"You want to be able to have your jaw receiving sound very clearly and transmitting it to your inner ear so that you can interpret your echolocation," she said. "But you also want to be able to bite down on the meal you're finding - especially if you're a killer whale hunting other marine mammals." These questions of form and function are where she hopes to bring her research next.

From sperm whales' hyper-specialized form of echolocation used to hunt squid in deep bathypelagic environments, to "essentially blind" river dolphins relying entirely upon echolocation to hunt fish in dark, muddy water, the unique evolutionary history and anatomy of toothed whales has allowed these animals to survive and thrive in diverse, extreme environments - none of which remain free of human impact.

(Michelle Pemberton, The Children's Museum of Indianapolis)

Studying the relationship between toothed whale diet, behavior, and anatomy may be helpful to understanding the consequences of a changing ocean. Not only are waters warming from growing greenhouse gasses in the atmosphere, but oceans worldwide are getting noisier from busy shipping traffic and marine resource exploration. Understanding the role that sound has played and continues to play in toothed whale ecology and evolution is vital to anticipating problems that might be posed by these new environmental conditions, from disrupting certain modes of feeding to potentially causing physical harm. And as apex predators, toothed whales can serve as key indicators of health for ecosystems as a whole - "canaries in a coal mine," known to scientists as 'sentinel species.' As it turns out, in the jig-saw of preserving the sea, toothed whales with their sound-sensitive jaws are an important piece of the puzzle. Their decline or demise would foreshadow immense loss of all other parts of the ocean world.

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Imagine hearing with your jaw - the very same jaw used to catch and eat your food. For the about 75 species of whales, dolphins, and porpoises of the Odonotocete family, also known collectively as the toothed whales, that is their reality.

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Teaching echolocation, particularly to individuals who are blind, involves several effective techniques that focus on utilizing sound reflections to navigate and understand the surroundings.

Students learn to produce consistent clicking sounds with their tongues. This is the most common method because the sound is sharp and easy to control. Research shows that regular practice with mouth clicks significantly enhances one's ability to detect objects and navigate through spaces.

Studies have demonstrated that both blind and sighted individuals can learn echolocation within ten weeks through structured training sessions, involving tasks such as identifying object positions and navigating obstacle courses.

This involves using different materials and objects to help students understand the variety of echoes they produce. For instance, distinguishing between echoes from glass, wood, and metal.

This technique helps refine the auditory discrimination skills necessary for effective echolocation. It also aids in identifying specific characteristics of objects, such as their density and material composition.

In AOP, students do not necessarily make sounds themselves but rather learn to interpret ambient sounds and their reflections from the environment. This method can be especially useful for young students or beginners who might find it difficult to produce consistent clicks initially.

It broadens the understanding of how sound interacts with various surfaces. Using virtual environments and sound simulations to create controlled training scenarios. Participants wear headphones and navigate through virtual spaces using pre-recorded clicks.

This provides a safe and controlled environment for beginners to practice without real-world consequences. It also allows for precise control over the acoustic properties of the training space, aiding in the fine-tuning of echolocation skills.

Q: How might the principles of echolocation training be integrated into educational programs for individuals recovering from brain injuries or neurological disorders?

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For years, a small number of people who are blind have used echolocation, by making a clicking sound with their mouths and listening for the reflection of the sound to judge their surroundings. Now, research published in PLOS ONE shows that people can learn click-based echolocation regardless of their age or ability to see, Alice Lipscombe-Southwell reports for magazine.

Researchers led by psychologist Lore Thaler at Durham University spent ten weeks teaching over two dozen people, some who were blind and some who were not, to observe and navigate their environments by echolocation. Participants attended two sessions per week for two to three hours each time.

After the training, the researchers compared the participants' ability to use echolocation to seven people who had been using the technique for over a decade. The researchers also followed up with blind participants three months later to see how the echolocation affected them long-term.

"I cannot think of any other work with blind participants that has had such enthusiastic feedback," says Thaler in a statement. "People who took part in our study reported that the training in click-based echolocation had a positive effect on their mobility, independence and well-being, attesting that the improvements we observed in the lab transcended into positive life benefits outside the lab."

Participants were between 21 and 79 years old, and included 12 people who are blind and 14 people who are not blind. Over their ten weeks of echolocation training, they faced tasks like using clicking to figure out whether the pair of disks in front of them had a larger disk at the top or bottom or to identify how a rectangle plank was oriented. Participants also navigated obstacles virtually in the lab, and outside of the lab, they navigated using clicking and a long cane.

The results showed that all of the participants could learn how to echolocate, regardless of their age or whether they were blind. Some of the study participants even did better at their tasks when compared to the seven expert echolocators, who have more than a decade of experience using echolocation to navigate.

"What made us explore it in the first place was that it is just such a fascinating skill, and that it has such great potential to help people who are blind and to investigate neuroplasticity on a more general level," writes Thaler to 's Ed Cara in an email. "We also plan to investigate how teaching and learning of this skill would scale up from the lab to professional instruction (i.e. how do people learn and benefit when they are not trained by researchers but by visual impairment professionals)."

The researchers also hope to find out whether echolocation could be taught to people who realize that they are losing their eyesight because of a degenerative illness, per the statement.

Thaler's previous research on echolocation identified the "cone of perception" created by each click, Nathan Hurst reported for Smithsonian in 2017. Clicks create a 60-degree cone where perception is most detailed, and past research has shown that information gathered from echolocation is processed in the same part of the brain that processes visual information.

"You could fill libraries with what we know about the human visual system," said Daniel Kish, who participated in the 2017 study and uses click-based echolocation, to Smithsonian in 2017. "But what we know about human echolocation could barely fill a bookshelf."

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People Can Learn Echolocation in Ten Weeks

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For years, a small number of people who are blind have used echolocation, by making a clicking sound with their mouths and listening for the reflection of the sound to judge their surroundings. Now, research published in PLOS ONE shows that people can learn click-based echolocation regardless of their age or ability to see, Alice Lipscombe-Southwell reports for magazine.

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Looking into learning how to echolocate, it appears to be a self taught skill. Daniel Kish taught himself to move around with echolocation after losing his vision while young. He produces a series of short, crisp clicking sounds and listens to how these sounds bounce off the surrounding landscape. Kish now teaches echolocation, providing a positive well-being to blind individuals. Daniel Kish's steps to learning Echolocation:

1. Practice tuning in

Noticing the way your sounds change around you

Exercise - sit in car and open window, try to differentiate between sounds

2. Pick your supplies

If you are a sighted person wanting to learn, you will want a blindfold

Getting rid on one sense give the less dominant ones more dominant

3. Chose an environment

The best is a quiet, open space room with little clutter

4. Practice your clicks

The “cluck” sound is bad, like two clicks on top of each other which masks the returning sound

A good click must be crisp

“You settle on whatever click you can do, and stick to it”

5. Start simple

Presence/absence (is something there?)

The location (what direction is it in?)

Distance (how far away is it?)

Learn how to listen to the bouncing sounds

6. Get moving

Do all of this while in motion

Different sounds indicate corners or doors

Have a partner making sure you are on the right track

7. Continue Practicing

Taking breaks every 30-45 minutes is important

Echolocation takes patience

Question: looking into sighted and non-sighted individuals, what differences arise between the two in learning echolocation?

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Daniel Kish navigates the world like a bat does-and he does so without ever leaving the ground.

After losing his vision as an infant, Kish taught himself to move around with the help of echolocation. Like bats, Kish uses his mouth to produce a series of short, crisp clicking sounds, and then listens to how those sounds bounce off the surrounding landscape. (Our winged neighbors tend to emit these clicks at frequencies humans can't hear, but Kish's clicks are perfectly audible to human ears.) From there, Kish makes a mental map of his environment, considering everything from broad contours-like walls and doors-down to textural details.

Kish now teaches echolocation, mostly to students who are blind. For these students, Kish believes that an echolocation practice can buoy confidence and independence. Kish's own experience is persuasive-he famously bikes along hilly, car-lined streets-and a growing body of scholarly research has begun to unpack exactly how expert echolocaters do their thing. This research has also backed up the idea that this skill is highly learnable. When researchers at the University of California, Berkeley, asked novice echolocators to use tongue clicks to determine which of the two objects in front of them was larger, the newbies were soon able to do so in a way that the scientists couldn't attribute to chance.

Whatever your sightedness, there's something to be said for learning to listen more attentively to sonic scenery. Kish believes that vision has a way of blunting the other senses unless people work to really flex them. Deft echolocators, he says, are able to perceive fine differences-distinguishing, say, between an oleander bush ("a million sharp returns") and an evergreen ("wisps closely packed together, which sound like a bit like a sponge or a curtain"). They're discovering sonic wonder wherever they go. We asked Kish to tailor a lesson for first-timers just learning to listen to the landscape.

1) Practice tuning in

Before you begin producing your own sounds, just practice noticing the ways that sounds change around you. Try this exercise next time you're in a car (assuming you're not in the driver's seat).

Crack open the window and close your eyes. This is a good chance to pass through a varied landscape pretty quickly, and begin to differentiate between sounds. "On a residential street, you should hear the sound of the car jump in and out as you pass other parked cars, possibly trees, posts, mailboxes, or houses near the curb," Kish says. "Everything we pass reflects the sound of our car differently." Prime yourself to pay attention to incidental soundtracks.

2) Pick your supplies

If you are a sighted person, you'll want a blindfold. "It's very, very difficult to discern these kinds of subtleties if your eyes are working at the same time," Kish says. Occluding one sense gives the less-dominant ones room to stretch their legs.

Now is also a good time to stock up on what you'll need for your practice sessions. First, you'll need a metal tray or a bowl, so make sure you've got one on hand. Once you start moving through space later on, it will also help to have a trekking pole or a cane, or at least a partner you trust to shout if you wander too far off base.

3) Choose an environment

Expert echolocators like Kish can get a bit fancier with their choices, and try to hear the character of a room. Tin decor, buttresses, or other accoutrements that might make a realtor swoon will also give Kish reason to perk up his ears. "It will sound more alive," he says. "It will sing to you."

For beginners, picking the right place is a bit of a Goldilocks situation: You don't want a flat field, where there's nothing for sound to bounce off. Then again, you ought to steer clear of spots where your hearing will be impeded by, say, a sea of carpet. "Probably the best is a fairly quiet, open space without a lot of clutter, maybe a non-reverberant room," Kish says.

4) Practice your clicks

Clicks are not created equal, and some of them will work against you. "The most commonly produced rubbish click is a 'cluck,'" Kish says. A cluck sounds something like two clicks on top of each other, which masks the returning sound. A good click can't be sloppy, and it must be possible to reliably reproduce.

For beginners, Kish says that a dental click fits the bill (this is a tsk-tsk sound, Kish says, "like you're disappointed"). Another contender is the sound you might use to prompt a horse to giddy-up; a "ch" sound, as in "check" or "church," is another option.

The key is finding the option that's comfortable for you. "You settle on whatever click you can do, and stick to it," Kish says.

5) Start simple

The goal with clicking is to take stock of three things. The first is presence/absence (is something there?). Then, the location (what direction is it in?). Finally, distance (how far away is it?).

To teach these skills, Kish often starts with this exercise: Students pair up with a partner who holds a bowl or flat paddle somewhere above their head. The student clicks, turns their head, and tries to gauge where the bowl is-straight ahead, or off to the side?

Kish doesn't click all the time-only when he needs to refresh the mental map he's working from. For beginning students, though, it's helpful to practice the physical mechanics of clicking, in order to learn how to listen to bouncing sounds.

6) Get moving

The next step is to do all of this while in motion. Walk along a hallway and try to listen for differences in sounds that might indicate corners or open doors.

At first, you'll shuffle and fumble through this exercise, and it's bound to be frustrating. Go ahead and ask your partner whether or not you're on the right track-but, if you're using a blindfold, keep it on. "The temptation is very strong to pop the blindfold off and on," Kish says. "I resist that because there is an adaptation process that has to happen here. You disrupt it entirely when you pull off the blindfold. I wouldn't use vision to spot-check an experience; I would try to avoid that."

7) Stop when you need to

Moving through the world in a new way can be both thrilling and thoroughly disorienting. Kish has found that people who are sighted, and are unaccustomed to not being able to rely on their vision, need to take breaks every 30-45 minutes. His blind students, for whom non-visual navigation is routine, can hang in longer.

Echolocation takes patience and practice. Kish cautions that it's hard to get good at this-it took him years. But trying it out can open your ears to the world.

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A beginner's guide to navigating with sound.

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Bats adjust their echolocation based on their environment and prey. Bats that emit higher frequency calls can tune their call characteristics such as directionality and frequency to capture prey better while counteracting the effects of attenuation in cluttered environments.

Bats emitting higher frequency calls can increasingly ignore clutter noises due to their acoustical axis, especially when prey is closer to them. Higher frequency callers experience greater attenuation resulting in weaker echoes from clutter compared to echoes from prey, enhancing their prey catching abilities

Sound attenuation increases drastically in the air with frequency. Higher frequency calls experience greater attenuation compared to lower ones due to their shorter wavelength. Higher frequency bats experience a trade-off between sonar range and resolution. Higher frequency calls provide better resolution and localization, they suffer greater attenuation, limiting the range of their calls.

Q:How do bats calibrate their echolocation techniques to balance trade-off between resolution & sonar range in different environmental layouts,considering the effects of frequency dependent attenuation & varying prey behavior?

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Abstract

The paper reviews current knowledge of intensity and directionality of bat echolocation signals. Recent studies have revealed that echolocating bats can be much louder than previously believed. Bats previously dubbed "whispering" can emit calls with source levels up to 110 dB SPL at 10 cm and the louder open space hunting bats have been recorded at above 135 dB SPL. This implies that maximum emitted intensities are generally 30 dB or more above initial estimates. Bats' dynamic control of acoustic features also includes the intensity and directionality of their sonar calls. Aerial hawking bats will increase signal directionality in the field along with intensity thus increasing sonar range. During the last phase of prey pursuit, vespertilionid bats broaden their echolocation beam considerably, probably to counter evasive maneuvers of eared prey. We highlight how multiple call parameters (frequency, duration, intensity, and directionality of echolocation signals) in unison define the search volume probed by bats and in turn how bats perceive their surroundings. Small changes to individual parameters can, in combination, drastically change the bat's perception, facilitating successful navigation and food acquisition across a vast range of ecological niches. To better understand the function of echolocation in the natural habitat it is critical to determine multiple acoustic features of the echolocation calls. The combined (interactive) effects, not only of frequency and time parameters, but also of intensity and directionality, define the bat's view of its acoustic scene.

Keywords: intensity, directionality, beam shape, bat, echolocation, biosonar

Introduction

The evolutionary success of bats is accredited to their ability, as the only mammals, to fly and navigate in darkness by echolocation, thus filling a niche exploited by few other predators. Over 90% of all bat species use echolocation to localize obstacles in their environment by comparing their own high frequency sound pulses with returning echoes (Griffin, 1958). The ability to localize and identify objects without the use of vision allows bats to forage for airborne nocturnal insects, but also for a diverse range of other food types including motionless perched prey or non-animal food items (Schnitzler and Kalko, 2001; Brinkløv et al., 2011; Geipel et al., 2013).

The agility and precision with which bats navigate and forage in total darkness, is in large part due to the accuracy and flexibility of their echolocation system. The echolocation clicks of the few echolocating Pteropodidae ( Rousettus) are fundamentally different from the echolocation sounds produced in the larynx that we focus on here, and thus not part of this review. Many studies have shown that bats adapt their echolocation calls to a variety of conditions, changing duration and bandwidth of each call and the rate at which calls are emitted in response to changing perceptual demands (Griffin et al., 1960; Schnitzler and Kalko, 2001). In recent years the intensity and directionality of echolocation signals has received increasing research attention and it is becoming evident that these parameters also play a major role in how bats successfully navigate and forage. To perceive an object in its surroundings, a bat must ensonify the object with enough energy to return an audible echo. Hence, the intensity and duration of the emitted signal act together to determine how far away a bat can echolocate an object. Equally important is signal directionality. Bat echolocation calls are directional, i.e., more call energy is focused in the forward direction than to the sides (Simmons, 1969; Shimozawa et al., 1974; Mogensen and Møhl, 1979; Hartley and Suthers, 1987, 1989; Henze and O'Neill, 1991). An object detectable at 2 m directly in front of the bat may not be detected if it is located at the same distance but off to the side. Consequently, at any given echolocation frequency and duration, it is the combination of signal intensity and signal directionality that defines the search volume, i.e., the volume in space where the bat can detect an object.

The aim of this review is to summarize current knowledge about intensity and directionality of bat echolocation calls, and show how both are adapted to habitat and behavioral context. Finally, we discuss the importance of active motor-control to dynamically adjust both signal intensity and directionality to solve the different tasks faced by echolocating bats.

Intensity

Call intensity is a main determinant of echolocation range, i.e., the distance from a bat where objects, such as obstacles and food, reflect echoes intense enough for detection. The more intense the call, the further sound travels from the bat and the larger the echolocation range. Emitted intensities (source level) of bat echolocation signals are referenced to a standard distance of 10 cm from the bat's mouth. Thus, when recording bats at a distance, one must add the transmission loss due to geometric spreading [20 × log ₁₀(R)] and frequency-dependent atmospheric attenuation (ANSI, 1995) over the distance from the bat to the microphone.

When Griffin first investigated how loud bats call, he found that insectivorous bats flying in open space, e.g., aerial hawking vespertilionids, called at around 110 dB SPL (Sound Pressure Level; re. 20 μPa at 0.1 m) and closed-space gleaners operating in or near vegetation, like the phyllostomid Carollia perspicillata, called at around 70 dB SPL (Griffin, 1958). Consequently, Griffin divided bats into two groups, the loud insectivorous bats, and the "whispering" gleaning bats. Recordings from the field have since shown that bats are orders of magnitude louder than what Griffin measured, and the border between loud and whispering is much blurrier than initially believed. Open-space insectivorous bats emit calls up to, and beyond, 140 dB SPL (Holderied et al., 2005; Surlykke and Kalko, 2008). Remarkably, even "whispering" bats are capable of emitting calls up to 110 dB SPL (Brinkløv et al., 2009). This means that, while echolocation in air is still a relatively short-range system, its range is considerably larger than first assumed.

The huge difference between the values for signal intensity obtained by Griffin and more recent measurements illustrates the great flexibility of the echolocation system. Bats dynamically adjust signal intensity to changes in their environment and the task at hand, lowering the output as they approach objects such as prey or vegetation. The dynamic range, or the difference between the loudest and the quietest calls emitted by individual bats is in the order of at least 30-40 dB for most species. When object detection occurs at long range or under predictable lab conditions most studies report a reduction in output level of around 6 dB for every halving of distance to the target (Hartley, 1992b; Hiryu et al., 2007, 2008; Brinkløv et al., 2010; Koblitz et al., 2010, 2011; Nørum et al., 2012). If the object reflects impinging sound like a point target, the echo level at the bats ears would increase by 12 dB per halving of distance if the bat emitted a constant source level. Thus, the consequence would be an enormous increase in echo level through a pursuit, e.g., +80 dB from detection at 5 m to capture at 5 cm, likely to overload central auditory processing. The output reduction of 6 dB per halving of distance removes half of the echo increase such that the sound pressure at the bat's ear increases by only 6 dB per halving of distance. Further, psychophysical experiments have shown that sensitivity on the receiver side is not constant, but decreases by the remaining 6 dB for each halving of distance probably due to contraction of the bats middle-ear muscles (Suga and Jen, 1975). Hence, in a predictable situation the combined adjustment of output and input results in echoes perceived at a relatively stable intensity (Henson, 1965; Suga and Jen, 1975; Hartley, 1992a). Data from more unpredictable situations in the natural environment have also indicated a 6 dB reduction in signal output intensity per distance halved. New data, however, show that the reduction in intensity for individual approaches is mostly much steeper in the wild, up to as much as 30 dB per halving of distance, with considerable variation. The relatively shallow slopes reported from other field studies are probably the result of pooling multiple sequences with steep slopes but initiated at different distances (Figure , Nørum et al., 2012). The results suggest that sudden detection of prey or obstacles at close range may prompt an initial dramatic intensity reduction. Curiously, for bats landing on an extended surface, the reduction in output intensity is likewise within the 6 dB per halving of distance range (Koblitz et al., 2011). If the sensitivity on the receiver side changes as well, this results in a gradual decrease in perceived echo strength as the bat approaches the surface.

There may be a less clear-cut separation between loud and whispering bats than previously assumed, but it is still evident that bats flying close to or within dense vegetation are considerably less intense than bats flying in open space. This is true for species that differ in overall habitat use, but also for individual bats switching between habitats with varying degrees of clutter. Under field conditions, the trawling insectivorous phyllostomid Macrophyllum macrophyllum lowers mean signal intensity from 111 dB SPL in open space to 105 dB SPL in semi-cluttered space. Signal intensity is further reduced to 100 dB SPL when M. macrophyllum navigates a small flight room, demonstrating an obvious dynamic adjustment of output intensity in response to varying degrees of habitat clutter (Brinkløv et al., 2010).

The adjustment of signal intensity in M. macrophyllum occurs in parallel with changes in signal duration and peak frequency. Open space calls are not only louder, but also longer and with lower peak frequency than those emitted in semi- or densely cluttered conditions. These changes all contribute to an increase in sonar range in open space. The increased duration increases the signal energy and the lower frequency reduces the effects of atmospheric attenuation. Attenuation of sound in air increases drastically with frequency (Lawrence and Simmons, 1982; ANSI, 1995) which presumably represents a major constraint for echolocating bats resulting in a trade-off between sonar range on one hand and resolution and localization on the other (Kalko and Schnitzler, 1993). The low intensities and high frequencies emitted by most gleaners in clutter likely indicate that sonar range is not an issue. Thus, the low intensities serve to prevent self-deafening and the high frequencies serve to increase resolution and localization (Kalko and Schnitzler, 1993).

The use of high frequencies also increases clutter rejection along the acoustic axis when the prey is closer to the bat than the clutter. This is because the increased atmospheric attenuation at higher frequencies will generate a relatively weaker echo the further away an object is. An increase in emitted frequency from 45 to 90 kHz increases atmospheric attenuation from 1.4 to 4 dB/m (at 25°C and 80% humidity). If clutter is present 0.5 m behind the prey, the prey/clutter echo-ratio will be 2.6 dB higher at 90 kHz than at 45 kHz, thus increasing prey conspicuousness.

An added advantage of using low intensity echolocation is that it may prevent prey from detecting an approaching bat. The sound pressure reaching the prey will always be higher than the echo returning to the bats ears, but eared insects, such as moths, generally have much higher hearing thresholds than bats (Wenstrup, 1984; Schmidt et al., 1992; Esser and Daucher, 1996; Koay et al., 1997; Surlykke et al., 1999). While intensity at the insect increases by 20 × log ₁₀(R) as the bat approaches, the echo the bat receives increases by 40 × log ₁₀(R). Thus, every time the bat halves the distance to the prey, the sound pressure increases with 6 dB at the prey and 12 dB at the bat. By concurrently reducing its output level by 6 dB, the bat maintains a constant sound pressure at the prey, but still increases the returning echoes by 6 dB. This keeps prey out of the loop while increasing echo strength for the approaching bat (Surlykke, 1988). By emitting low intensity calls, the aerial hawking bat, Barbastellus barbastellus, can detect its prey before the prey detects the bat, and by reducing its output level during approach it can remain undetected during the pursuit (Goerlitz et al., 2010). The low-intensity calls from B. barbastellus do come at a cost; a reduction in output level also reduces the detection distance for the bat, but given that B. barbastellus feeds almost exclusively on eared insects, the benefit of not being detected seems to outweigh the cost of operating at short range.

Directionality

A directional echolocation signal provides bats with a number of advantages over an omni-directional signal: (1) inherent directional information; by focusing sound in the forward direction, returning echoes are likely to originate from that direction, simplifying object localization. (2) A reduction in clutter; when less sound is radiated to the back and sides of the bat, less sound is reflected off objects of little or no interest in these directions, reducing the amount of information the bat has to process. (3) An increase in source level (on-axis intensity); by focusing energy in a narrow cone instead of radiating it in all directions. On the other hand, a highly directional sound beam will also restrict the bats "field of view" which may be a disadvantage in certain situations.

Beam shape is a spatial filter that determines what information is available to the bat and what information is filtered out before echoes return. This may be critical in light of the very short time bats have to make decisions. A typical pursuit often takes less than half a second and the time to process information and make decisions on a call-to-call basis is even shorter, perhaps a few tens of milliseconds. A clear advantage of a highly adapted and dynamic emission (and reception) system is a reduction in processing load on the receiving side i.e., smart sensing over smart processing. This may be one of the adaptations that allow for the very fast reaction times in echolocating bats, subsequently leading to high foraging, and, in turn, evolutionary, success.

Beam shape is determined by the size and shape of the sound emitter and the frequency of the emitted signal (Strother and Mogus, 1970; Urick, 1983) such that an increase in size or frequency generates a more directional sound beam (Figure ). Frequency is easily measured, but emitter size and shape is not as apparent when dealing with live animals, let alone bats in flight. For bats emitting sound through the open mouth, gape size presumably dictates directionality. Opening the mouth more while emitting a given frequency will generate a more directional beam and vice versa (Surlykke et al., 2009). For nose emitting bats, beam shape is likely dictated by the distance between the nostrils and the size and shape of the nose-leaf (Hartley and Suthers, 1987).

Beam directionality has so far been measured in 17 bat species from seven different families (Figure ). The methods differ substantially. Many studies were performed on restrained bats, often with calls elicited through stimulation of the brain by implanted electrodes (Shimozawa et al., 1974; Schnitzler and Grinnell, 1977; Mogensen and Møhl, 1979; Hartley and Suthers, 1987, 1989; Henze and O'Neill, 1991; Hiryu et al., 2006). This made it easy to control the bat's position and acoustic axis, but probably prevented active beam shape control by the bats, and in some cases produced calls very different from those produced by freely behaving bats. A few early and most later studies focus mostly on freely behaving bats in the lab (Griffin, 1958; Simmons, 1969; Ghose and Moss, 2003; Jakobsen and Surlykke, 2010; Jakobsen et al., 2012, 2013) with one report from the field (Surlykke et al., 2009). In spite of the large differences in methodology, a few general trends emerge from the data set. It is clear that all bats recorded emit directional signals and it is also clear that they emit a bilaterally symmetrical sound beam. Most results come from the Vespertilionidae (nine species), where directionality is remarkably uniform across species for bats echolocating under similar conditions, in spite of large differences in bat size and emitted frequency (Figure ). This indicates that directionality may have been one of the major constraints on the evolution of echolocation frequency, forcing small bats to echolocate at higher frequencies to produce a sufficiently directional beam (Jakobsen et al., 2013). Echolocation frequency is also important for echo reflection (Møhl, 1988; Pye, 1993) and ranging accuracy (Stamper et al., 2009) and frequency-dependent directionality may help bats segregate target and clutter echoes (Bates et al., 2011). Thus, echolocation frequency is probably under several simultaneous evolutionary constraints. There is a negative correlation between size and echolocation frequency in most families of bats (Jones, 1999), and it will be interesting to see if this translates into a convergence of beam width for other families than the Vespertilionidae. Data from the emballonurids seem to deviate from this pattern. Cormura brevirostris emits a narrower beam in the flight cage than does Saccopteryx bilineata ( DI of 11.5 and 9.3 dB, respectively, Figure ), but given that emission patterns from only two species have been recorded so far (Jakobsen et al., 2012), conclusive evidence is still lacking. In contrast to other bats Phyllostomids do not appear to show correlation between body size and emitted frequency. Curiously, data show that nose-leaf size is not correlated with body size either in phyllostomids (Hartley and Suthers, 1987; Jones, 1999). Even though the nose-leaf is not the emitter per se, it has been shown to define the vertical directionality (Hartley et al., 1989; Vanderelst et al., 2012). Thus, if directionality is a driving force for echolocation frequency in phyllostomids as well, we would expect to find that the emitted frequency is correlated to the size of the nose-leaf and the nostril separation but not to body size.

Bats adapt many features of their echolocation calls in response to changes in their surroundings and to behavioral context. Signal bandwidth and peak frequency are increased in many species when they navigate in cluttered space probably to improve resolution and localization accuracy (Kalko and Schnitzler, 1993). Further, an increase in frequency will result in an increase in directionality. However, as directionality depends on both frequency and effective emitter size, combined changes of the two may result in the opposite effect. This seems to be the case for the vespertilionid Myotis daubentonii. When navigating in the field, M. daubentonii emits calls with lower peak frequency than in the lab (45 vs. 55 kHz), which by itself would produce a less directional beam. Yet, the signals are more directional in the field than in the lab, presumably because the bats also increase their emitter size by opening the mouth wider (Surlykke et al., 2009).

Echolocating bats must adjust directionality not only to adapt to the environment, but also in response to rapid changes in the perceived echo-scene, especially when hunting prey doing their best to escape. At least six orders of insects have ultrasound sensitive ears and exhibit "anti-bat tactics" i.e., they perform erratic escape behaviors like power dives and passive falls in response to intense ultrasound (Miller and Surlykke, 2001). The relatively high directionality of echolocation signals will, in close proximity to prey, become a disadvantage to the bat since the prey only has to move a short distance to escape the bat's sound beam. M. daubentonii and Eptesicus serotinus (Vespertilionidae) in fact broaden their beam in the last part of prey pursuit by lowering call frequency by roughly an octave (Jakobsen and Surlykke, 2010). A similar frequency drop is seen in a large number of insectivorous vespertilionids and is known as Buzz II (Figure ). Buzz II calls have been thought an artifact of the extremely high repetition rate of calls emitted during this stage of pursuit, sometimes exceeding 200 calls/s (Kalko and Schnitzler, 1989; Faure and Barclay, 1994). From a purely physiological perspective, however, this seems unlikely as such fast call rates would result in additive tension build-up in the laryngeal muscles, ultimately increasing, rather than reducing call frequency during the buzz (Ratcliffe et al., 2013). Further, many species of echolocating bats use repetition rates as high as vespertilionids but without the frequency drop (Surlykke et al., 1993; Ibáñez et al., 2002). Thus, we argue that the lower frequency of Buzz II calls is not a non-functional epiphenomenon. Rather, it is an adaptive feature that broadens the echolocation beam considerably in the last phase of pursuit to counter the evasive maneuvers performed by many eared insects when exposed to intense ultrasound (Jakobsen and Surlykke, 2010). This argument is corroborated by recent results from horseshoe bats. During prey pursuit, the Japanese greater horseshoe bat, Rhinolophus ferrumequinum nippon, will likewise broaden its echolocation beam, but only when the prey moves (Matsuta et al., 2013). In horseshoe bats beam broadening is, contrary to vespertilionids, not achieved by lowering the call frequency. The mechanism underlying the change in beam shape is still unknown, but it is likely facilitated by manipulating the fine structures of the nose leaf (Feng et al., 2012).

As discussed above, the optimal directionality is likely to differ from situation to situation, but also between bats with different feeding ecology. Gleaning bats, foraging in dense vegetation for inconspicuous stationary food items, presumably benefit more from a narrower beam shape than an open space aerial hawking bat. Directionality data from the frugivorous bat, C. perspicillata, and the frog-eating bat, Trachops cirrhosus, corroborate this. Both phyllostomid species have echolocation beam widths with DI of 17 dB (half amplitude angle of ~15°) when flying in a flight cage (Brinkløv et al., 2011, Surlykke et al., submitted). This is considerably narrower than the 10-12 dB (half amplitude angle of ~37°) measured for aerial hawking bats flying in similar conditions (Ghose and Moss, 2003; Jakobsen et al., 2013) (Figure ). So far the only report of active beam shape adjustments in nose-emitting bats come from the horseshoe bats (Matsuta et al., 2013), an adjustment likely facilitated by manipulating the shape of the nose leaf. However, the phyllostomid, M. macrophyllum, shifts maximum energy to the second harmonic in the open, but to the third (or fourth) harmonic in cluttered space (Brinkløv et al., 2010), indicating that phyllostomid bats may also alter beam shape by changing emitted frequency.

Modeling emission patterns

Modeling bats as physical sound emitters allows predictions about parameters, which cannot or have not been measured. The simple piston model describes the beam pattern of a rigid circular piston oscillating in an infinite baffle and has been used as a model for the emission pattern of mouth emitting bats (Strother and Mogus, 1970; Mogensen and Møhl, 1979):

R P(θ)=|2×J 1(k×a×sin(θ))k×a×sin(θ) |

R p(θ) is the ratio between the on-axis pressure and the pressure at an angle θ, J ₁ is a first order Bessel function of the first kind, k, the wavenumber = 2π/λ, λ the wavelength, and a is the radius of the piston. Even though, there are a number of obvious differences between bats and the model, the model performs surprisingly well in predicting the emission pattern from mouth emitting bats (Mogensen and Møhl, 1979; Hartley and Suthers, 1989; Jakobsen and Surlykke, 2010; Jakobsen et al., 2012).

The emission pattern from nose emitting phyllostomid bats has been modeled using a two point-source model, but with limited success in particular for freely flying bats (Strother and Mogus, 1970; Hartley and Suthers, 1987; Brinkløv et al., 2011). A model simulating two small pistons with the same separation as the nostrils appears a much better approximation to the horizontal directionality of phyllostomid bats (Vanderelst et al., 2010), but the vertical pattern has so far not been successfully modeled by simple means (see Zhuang and Müller, 2006, 2007; Vanderelst et al., 2010, 2012 for more advanced procedures).

The directionality and intensity of sound signals are not independent features. Intensity changes with directionality, such that an increase in directionality will lead to a corresponding increase in intensity along the acoustic axis. The directivity index (DI) of the source reflects this relationship. A DI of e.g., 18 dB implies that sound intensity along the acoustic axis is 18 dB higher than it would be for an omnidirectional sound source radiating sound with the same acoustic power (Figure ). For the piston model, the DI simply follows from the relation between size and wavelength:

where k = 2π/λ, λ is the wavelength, and a is the radius of the piston. Using measured data, the calculation of DI is slightly less simple. It requires an estimation of the sound field behind the bat and assumes that the beam is rotationally symmetric (Møhl et al., 2003).

Hence, by increasing or decreasing the directionality of the signal, the on-axis intensity inherently changes as well. M. daubentonii emits a source level of 111 dB SPL in the lab and 119 dB SPL in the field. Since the call is broader in the lab ( DI = 11 dB) than in the field ( DI = 16 dB) it follows that the bat only increases its output intensity by 3 dB while the remaining 5 dB are accounted for by the greater directionality in the field (Surlykke et al., 2009).

The increase in on-axis intensity with increasing directionality also means that increasing the signal frequency does not necessarily lead to a reduction in detection distance, in spite of the increased atmospheric attenuation at higher frequencies. This is because an increase in frequency increases the signal directionality and thereby the on-axis sound level. Again the situation is simple for the piston model, where a change in frequency from f ₁ to f ₂ leads to a change in DI of:

The total atmospheric attenuation depends on the distance the sound travels, whereas, an increase in on-axis sound level affects the source level and thus echo level irrespective of distance. Thus, at short echolocation ranges bats can increase frequency to achieve a higher directionality without sacrificing sonar range. At longer ranges the increase in atmospheric attenuation outweighs the increase in source level. For example a doubling in frequency from 25 to 50 kHz, increases DI and thus source level by 6 dB while the atmospheric attenuation increases from 0.7 to 1.7 dB/m (at 20°C and 50% humidity). Thus, up to a distance of 3 m (two-way travel distance: 6 m), the increased atmospheric attenuation at 50 kHz does not outweigh the increase in source-level. Due to the non-linear increase in atmospheric attenuation with frequency in air, the distance where these two effects cancel each other out depends on the absolute frequencies (Figure ).

Many factors combine to define the optimal echolocation signal for a given situation. There are clear differences between bats with different feeding ecologies even when they navigate similar scenarios, indicating a critical role of feeding ecology for how evolution has shaped echolocation signals. Many phyllostomids, such as C. perspicillata, feed primarily on fruit and must navigate dense vegetation. Pipistrellus pygmaeus is an example of a typical vespertilionid bat hunting moving insects in open fields or along forest edges. The requirements to the sonar systems of these two bats are very different and reflected in the combination of emitted intensity, directionality, and frequency, even when the bats are flying under similar conditions. In the lab, P. pygmaeus emits calls at 111 dB SPL with a DI of 12 at 55 kHz (peak frequency). Under similar conditions, C. perspicillata emits 99 dB SPL, with a DI of 17 dB and a peak frequency of 90 kHz. Figure shows the acoustic field of view for the two species and illustrates that the combined effects of intensity, directionality, and frequency generate dramatically different search volume for the two bats. The aerial hawking P. pygmaeus uses a sonar signal of much longer range and broader width than the gleaning C. perspicillata. P. pygmaeus searching for moving insect prey can probably "afford" to scan a relatively large volume of space with each call because its quarry will move in the foreground and thus stand out. C. perspicillata, on the other hand, must detect an inconspicuous (motionless) fruit-target in heavy clutter. By reducing the ensonified search volume it probably also focuses its attention on a smaller area and thereby increases the likelihood of detecting desirable objects caught in the sonar beam (Dukas, 2004).

Conclusion

The combined research on intensity and directionality of echolocation calls from bats show clear differences between restrained and unrestrained bats, and between bats flying in the lab and in the field. These differences highlight the huge flexibility of the echolocation system and highlight the importance of active motor control for perception through echolocation. At the same time, they point to the importance of recording naturally behaving bats in the wild.

The volume of space a bat probes with its echolocation beam is a product of the emitted frequency, intensity, directionality, and call duration. The combined effect of adjustments to these components can result in dramatic changes in the overall search volume. The dynamic control of all acoustic features probably plays a key role in the flexibility and adaptability of bat echolocation and is thus a major contributor to their extreme evolutionary success across a vast range of habitats worldwide. This emphasizes the importance of determining all acoustic features, not just frequency and time parameters, to understand the function of echolocation and its adaptation through evolution to habitats and behavioral contexts.

While our knowledge of both intensity and directionality has increased substantially over recent years, it is clear that we are still barely scratching the surface. Presently, we have directionality measurements from only 17 out of more than 1000 species of echolocating bats. So what appears a general rule today may yet prove to be the exception.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

We thank two reviewers for their helpful comments on the manuscript. The work was funded by the Danish national research council (FNU) and the Carlsberg foundation.

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Articles from Frontiers in Physiology are provided here courtesy of Frontiers Media SA

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Intensity and directionality of bat echolocation signals

# data[].attributes.attachment_link.description
The paper reviews current knowledge of intensity and directionality of bat echolocation signals. Recent studies have revealed that echolocating bats can be much louder than previously believed. Bats previously dubbed "whispering" can emit ...

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Marine Echolocation as a Mechanism of Evolution

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Marine Echolocation as a Mechanism of Evolution

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In marine animals, echoes are processed on a “Click by Click basis”. In order to keep up with vision animals, neural responses must be 100 times faster in echolocating animals.

For example, just before a kill, a harbour porpoise clicks nearly 500 times a second, and if they wait for the echo to return they would need a response time 100x faster than human eyes

Vance et al (a scientist) decided to track predator and prey in order to see the response time of echolocating animals. He attached sound and movement reactors to beaked whales and harbour porpoises. Both adapted their click rate (used to echolocate) when they are  near prey

Vance et al concluded these animals brains are similar to that of visual animals as they both responded groups of 10 clicks

Human landfill and sound pollution disrupts the echolocation process. As a result toothed whales adapt their clicking rates to trace prey within 50-200ms of prey escape movements

More specifically, they use echolocation to catch prey while maintaing a large distance.They then switch to become more reactive when they are in closer proximity and their bow-wave can be detected by prey

How might the successfulness of echolocating marine species be useful to scientists studying sound pollution and climate change?

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Echolocating toothed whales use ultra-fast echo-kinetic responses to track evasive prey

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Echolocating toothed whales can detect and react to sudden prey movements during close approaches with speeds similar to ultra-fast tracking responses in human vision.

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Sezual - The Project of Efficient Echolocation

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Sezual - The Project of Efficient Echolocation

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Galimzham Gabdreshov was inspired by Daniel Kish, innovating and beginning his project, Sezual. After realizing that several companies offer devices to enhance vision but none use echolocation regardless of the fact that 285 million visually impaired people across the globe, 39 mission and totally blind, Gabdreshov knew he had to do something. Sezual helps the blind visual objects in three dimension within a radius of 15 meters. This device is worn around the neck and emits a high pulse click that then is selected off surrounding objects, providing information on their distance and shape. This image is then perceived in the visual cortex of one's brain, even allowing individuals to identify the material. Visually impaired individuals navigate, work, travel, and life their life to the fullest. One another note, this innovation does only help blind indiviuals but can we used to help those that are not blind, such as, firefighters rescuing people in visually challenging circumstances. This project is looking for partners and financing, to advance the project.

Question: What other projects utilize echolocation and are being advanced? Are these other innovations closer to being sold internationally?

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A Kazakh start-up helps the blind - through echolocation

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Can echolocation technique be used by people without sight? An innovative start-up in Kazakhstan, Sezual, has developed echolocation for human beings, with support from the World Bank.

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Learning to echolocate in sighted people: a correlational study on attention, working memory and spatial abilities

# data[].attributes.subject
Learning to echolocate in sighted people: a correlational study on attention, working memory and spatial abilities

# data[].attributes.body
Echolocation can be beneficial for the orientation and mobility of visually impaired people

There are considerable individual difference for acquiring thes skin

In learning to echolocate that are various factors affecting it, including; sustained and divided attention, working memory and spatial abilities

Positive correlation between improvement in echolocation and sustain divided attention

Echolocation could be an additive value for blind people

The use of echolocation is not only useful for navigating, but it can also have important benefits for the representation of auditory space in general

Echolocation is predominantly trained by orientation and mobility instructors

Could advance insights to possible cognitive processes for learning to echolocation, that could be implemented into intervention programs to train echolocation

What technologies/techniques could be put into echolocation porgrams to improve navigation skills for visually impaired individuals.

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Learning to echolocate in sighted people: a correlational study on attention, working memory and spatial abilities

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Affiliations

¹ Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, 6500 HE, Nijmegen, The Netherlands. m.ekkel@pwo.ru.nl.

² Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.

³ Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, 6500 HE, Nijmegen, The Netherlands.

⁴ School of Psychology, Australian Catholic University, Melbourne, Australia.

Affiliations

¹ Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, 6500 HE, Nijmegen, The Netherlands. m.ekkel@pwo.ru.nl.

² Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.

³ Behavioural Science Institute, Radboud University Nijmegen, Postbus 9104, 6500 HE, Nijmegen, The Netherlands.

⁴ School of Psychology, Australian Catholic University, Melbourne, Australia.

Abstract

Echolocation can be beneficial for the orientation and mobility of visually impaired people. Research has shown considerable individual differences for acquiring this skill. However, individual characteristics that affect the learning of echolocation are largely unknown. In the present study, we examined individual factors that are likely to affect learning to echolocate: sustained and divided attention, working memory, and spatial abilities. To that aim, sighted participants with normal hearing performed an echolocation task that was adapted from a previously reported size-discrimination task. In line with existing studies, we found large individual differences in echolocation ability. We also found indications that participants were able to improve their echolocation ability. Furthermore, we found a significant positive correlation between improvement in echolocation and sustained and divided attention, as measured in the PASAT. No significant correlations were found with our tests regarding working memory and spatial abilities. These findings may have implications for the development of guidelines for training echolocation that are tailored to the individual with a visual impairment.

Keywords: Attention; Echolocation; Perception; Visual impairment.

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Conflict of interest statement

The authors declare that they have no conflict of interest.

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national center for biotechnology information

# data[].attributes.attachment_link.title
Learning to echolocate in sighted people: a correlational study on attention, working memory and spatial abilities - PubMed

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Echolocation can be beneficial for the orientation and mobility of visually impaired people. Research has shown considerable individual differences for acquiring this skill. However, individual characteristics that affect the learning of echolocation are largely unknown. In the present study, we exa ...

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The usage of echolocation to develop new technologies to assist visually impaired people in navigating the environment.

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The usage of echolocation to develop new technologies to assist visually impaired people in navigating the environment.

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Echolocation is used to develop technologies such as sonar, radars, and more. Echolocation is also now being used to assist visually impaired people, by making new creations that help them. One being the Sonic Eyewear Project. This is a project that creates echolocation technology that is built into designer frames for visually impaired individuals. Unlike other assisting objects, it produces flashes of sound energy to echo and alert nearby objects to avoid collisions and ensure safety.

Technologies that use echolocation for assistance overall helps visually impaired people with their safety, well-being, awareness, and confidence.

Another huge benefit of Flash Sonar is obstacle detection from a long distance away. People that have mastered Flash sonar detect large object from about 30 feet away, and small objects from 15 feet away.

Next Question: What are some challenges that experts face trying to innovate assistance for blind people and what researches and measures do they do?

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Echolocation compared to human hearing, and effects of pressure and temperature on echolocation.

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Echolocation compared to human hearing, and effects of pressure and temperature on echolocation.

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Human Hearing: Hearing depends on a series of steps that change the sound waves in the air into electrical signals. Our auditory nerves then carry these signals into the brain.

Echolocation: Echolocation is the process of emitting sound and listening to the echoes of the sound waves reflections of different objects in the environment.

Most shallow depth marine mammals rely on faster sound wave transmission because they are less territorial & travel in larger groups that need consistent communication and navigation between each other. Compared to marine mammals at deeper depths where pressure is higher and temperature is higher as well so mainly whales use echolocation to communicate between smaller pods that are more spread out due to whales being highly territorial.

Links: https://www.nidcd.nih.gov/health/how-do-we-hear

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/echolocation#:~:text=Publisher%20Summary-,Echolocation%20is%20the%20process%20in%20which%20an%20animal%20obtains%20an,hear%20echoes%20from%20large%20obstacles.

https://www.fisheries.noaa.gov/national/science-data/ocean-noise

Next Question: How do the mechanisms of human hearing compare to those of echolocation in animals.