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As musicians the ear is our most important tool, without them we would be lost with our instruments and life would be very dull and grey. In this assignment I will look at the inner workings of the ear and how it perceives sound in different way's, how hearing loss happens and how to prevent it.

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Hearinglink.org  describe the anatomy of the ear quite clearly below:

"The three parts of the ear anatomy are the outer ear, the middle ear and the inner ear. The inner ear is also called the cochlea. (‘Cochlea’ means ‘snail’ in Latin; the cochlea gets its name from its distinctive coiled up shape.)

The outer ear consists of the pinna, ear canal and eardrum
The middle ear consists of the ossicles (malleus, incus, stapes) and ear drum
The inner ear consists of the cochlea, the auditory (hearing) nerve and the brain
Sound waves enter the ear canal and make the ear drum vibrate. This action moves the tiny chain of bones (ossicles – malleus, incus, stapes) in the middle ear. The last bone in this chain ‘knocks’ on the membrane window of the cochlea and makes the fluid in the cochlea move. The fluid movement then triggers a response in the hearing nerve."

How this works is pretty simple with regards to the diagram below, sound vibrations are formed from acoustic energy, the sound waves enter the ear and travel along the ear canal until they meet the ear drum, this is where the sound wave is transformed into mechanical energy as the sound vibrates the ear drum and and the 3 bones behind it (Malleus, Incus, Stapes) the motion of the stapes against the oval window pass the sound to the inner fluid of the cochlea causing waves. The cochlea is the seashell shaped structure below, the start of the cochlea is where we hear high frequencies towards the back of it is where we pick up lower frequencies. The fluid inside the cochlea vibrates and causes the basilar membrane to vibrate and becomes electrical energy. This stimulates the organ of corti on top of the basilar membrane and the electrical energy travels to the brain through the auditory nerve where it makes sense of the sound, and this all takes place in a flash.

The ear canal: The ear canal is also called the the external acoustic meatus is basically the tunnel which acoustic energy travels through to the ear drum.

The ear drum: Also called the tympanic membrane is the conical shaped part below which seperates the outer and middle ear. It transmits sound to the ossicles.

The ossicles: These are the 3 small bones  (Malleus, Incus, Stapes) which transmit the sound to the inner ear.

Eustachian Tube: This is a tube which links the ear with the back of the nose, it equalises pressure for the proper transmission of sound.

Oval window: Also called the fenestra vestibuli is the opening that leads from the middle ear to the inner ear.

Cochlea: The Cochlea is the sea shell shaped conical bone structure if the inner ear it is comprised of the following main parts:

Three Scalae (Chambers): The vestibular duct, the tympanic duct and the cochlear duct.
The helicotrema, Ressiner's membrane, The basliar membrane, The organ of corti, and stereocilia.
"The cochlea is a portion of the inner ear that looks like a snail shell (cochlea is Greek for snail.) The cochlea receives sound in the form of vibrations, which cause the stereocilia to move. The stereocilia then convert these vibrations into nerve impulses which are taken up to the brain to be interpreted. Two of the three fluid sections are canals and the third is a sensitive 'organ of Corti' which detects pressure impulses which travel along the auditory nerve to the brain. The two canals are called the vestibular canal and the tympanic canal"

The Basilar membrane: this is a very important and interesting part of the ear. it is like the string of a guitar in how it reacts, it has different width, stiffness and mass along its length and moves like a wave, the basilar membrane allows us to determine different frequencies, it is narrowest at the start of the cochlea which allows us to pick up high frequencies and widest and the end or apex of the cochlea which allows us to pick up low frequencies.

The vestibular system of the inner ear is dedicated to balance and spatial orientation, it sends signal which control our eye movements and help us determine rotation like when we are upside down. "Together with the basilar membrane it creates a compartment in the cochlea filled with endolymph, which is important for the function of the spiral organ of corti. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth."

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The Mayo Clinic outlines some of the causes and risk factors of damaging your hearing:

"Causes of hearing loss include:

Damage to the inner ear. Aging and exposure to loud noise may cause wear and tear on the hairs or nerve cells in the cochlea that send sound signals to the brain. When these hairs or nerve cells are damaged or missing, electrical signals aren't transmitted as efficiently, and hearing loss occurs. Higher pitched tones may become muffled to you.

It may become difficult for you to pick out words against background noise. Heredity may make you more prone to these changes. This type of hearing loss is known as sensorineural hearing loss, which is permanent.

A gradual buildup of earwax. Earwax can block the ear canal and prevent conduction of sound waves. This can be restored with earwax removal.

Ear infection and abnormal bone growths or tumors. In the outer or middle ear, any of these can cause hearing loss.

Ruptured eardrum (tympanic membrane perforation). Loud blasts of noise, sudden changes in pressure, poking your eardrum with an object and infection can cause your eardrum to rupture and affect your hearing.

Risk factors

Factors that may damage or lead to loss of the hairs and nerve cells in your inner ear include:

Aging. Degeneration of delicate inner ear structures occurs over time.

Loud noise. Exposure to loud sounds can damage the cells of your inner ear. Damage can occur with long-term exposure to loud noises, or from a short blast of noise, such as from a gunshot.

Heredity. Your genetic makeup may make you more susceptible to ear damage from sound or deterioration from aging.

Occupational noises. Jobs where loud noise is a regular part of the working environment, such as farming, construction or factory work, can lead to damage inside your ear.

Recreational noises. Exposure to explosive noises, such as from firearms and jet engines, can cause immediate, permanent hearing loss. Other recreational activities with dangerously high noise levels include snowmobiling, motorcycling or listening to loud music.

Some medications. Drugs, such as the antibiotic gentamicin and certain chemotherapy drugs, can damage the inner ear. Temporary effects on your hearing — ringing in the ear (tinnitus) or hearing loss — can occur if you take very high doses of aspirin, other pain relievers, antimalarial drugs or loop diuretics.

Some illnesses. Diseases or illnesses that result in high fever, such as meningitis, may damage the cochlea"

In my own opinion hearing loss is down to a lack of common sense or awareness, (not including accidents, illness or other factors out of our control.) I believe that most people just aren't aware of how serious hearing loss or conditions like tinitus can actually be, tinnitus can practically drive someone mad and I am personally aware of at least one case where someone has committed suicide as a direct result of the torture of tinnitus. I don't believe that there is enough done to warn people of the dangers.

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Our ears have an inbuilt mechanism in the middle ear called the acoustic reflex which helps us control the amount of loud volumes and damaging frequencies we are experiencing by contracting to control the level of sound and protect the eardrum, however sometimes hearing damage can be unavoidable and we must take further measures.

Everydayhealth.com give some simple tips on how to avoid hearing loss:

"Minimize your exposure to loud noises that are persistent.

Never listen to music through headphones or ear buds with the volume all the way up.

Wear ear plugs or protective earmuffs during any activity that exposes you to noise at or above 85 decibels.

See your doctor about a baseline hearing test, called an audiogram, to find out if you already have some early hearing loss."

I personally use ear protectors when I am at gigs or live events where the music is too loud as much as possible, recently I was at the output conference in Belfast and got speaking to a representative of the musicians charity "help musicians NI" he informed me that the charity provides full clinical hearing tests and bespoke in ear protectors for only £40 (£30 if you are a member of the musicians union) this would usually cost hundreds of pounds so in my opinion this is a very worthwhile cause for any working musician. you can find it here: https://www.hearformusicians.org.uk

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Wikipedia says:

"Sound localization is a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space (see binaural recording, wave field synthesis).

The sound localization mechanisms of the mammalian auditory system have been extensively studied. The auditory system uses several cues for sound source localization, including time- and level-differences (or intensity-difference) between both ears, spectral information, timing analysis, correlation analysis, and pattern matching.

These cues are also used by other animals, but there may be differences in usage, and there are also localization cues which are absent in the human auditory system, such as the effects of ear movements. Animals with the ability to localize sound have a clear evolutionary advantage."

In simple english, the cues spoken about here are referencing:

"The distance cues are the loss of amplitude, the loss of high frequencies, and the ratio of the direct signal to the reverberated signal."

This basically means we are able to tell the direction and distance of where a noise has come from because our brain is able to tell the subtle differences in volume and the speed which the sound travels to each ear, for example if someone shouts from the left side of a room we are able to tell because the ears sent the sound to the brain on the left side quicker than the right, this is called inter aural delay which is the time difference between a sound reaching either ear. The head and the back of the ears also act as a barrier for the sound wave so that we can tell if a sound has come from behind or infront of us, this is called inter aural intensity difference, it will help with the location of the scource of a sound as one side of the head will have a greater intensity than the other, through this we lose some of the higher end frequencies which helps decipher direction. we are all much better at listening than we think.

More from wikipedia on high and low frequency perception:

"Evaluation for low frequencies[edit]

For frequencies below 800 Hz, the dimensions of the head (ear distance 21.5 cm, corresponding to an interaural time delay of 625 µs) are smaller than the half wavelength of the sound waves. So the auditory system can determine phase delays between both ears without confusion. Interaural level differences are very low in this frequency range, especially below about 200 Hz, so a precise evaluation of the input direction is nearly impossible on the basis of level differences alone. As the frequency drops below 80 Hz it becomes difficult or impossible to use either time difference or level difference to determine a sound's lateral source, because the phase difference between the ears becomes too small for a directional evaluation.[11]

Evaluation for high frequencies[edit]

For frequencies above 1600 Hz the dimensions of the head are greater than the length of the sound waves. An unambiguous determination of the input direction based on interaural phase alone is not possible at these frequencies. However, the interaural level differences become larger, and these level differences are evaluated by the auditory system. Also, group delays between the ears can be evaluated, and is more pronounced at higher frequencies; that is, if there is a sound onset, the delay of this onset between the ears can be used to determine the input direction of the corresponding sound source. This mechanism becomes especially important in reverberant environments. After a sound onset there is a short time frame where the direct sound reaches the ears, but not yet the reflected sound. The auditory system uses this short time frame for evaluating the sound source direction, and keeps this detected direction as long as reflections and reverberation prevent an unambiguous direction estimation.[12] The mechanisms described above cannot be used to differentiate between a sound source ahead of the hearer or behind the hearer; therefore additional cues have to be evaluated."

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I decided to create a binaural recording to illustrate sound localization, I came up with a simple trap style drum beat using a native instruments Maschine studio and its on board software, I then recorded 3 different synth parts by plugging a microkorg xl into a focusrite 2i4 , the synth parts where recorded in mono and only coming out of the left side of the speakers, the challenge was to create the binaural effect by using the Brauer motion plugin from waves.

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The Brauer motion plugin from waves is an invaluable tool for creating dynamics in mixes and interesting panning techniques to breath life into music.
I have used it to give my experimental track the surround sound feel of a binaural composition.
The effect that this is gives is basically and auditory illusion, by effecting the volume and frequencies of the sounds it is essentially mimicking the effects of inter aural delay and intensity as described in my sound localization page, this plugin is cutting the necessary high frequencies and adding them back again in such a way threat gives the impression that the sound is coming from in front or behind and circling around the head, the orbiting effect I mentioned.
The motion plugin gives you the capabilities to control speed, width and depth of the panning.

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As part of an experiment to illustrate hearing localisation and distance perception I recorded a simple trap instrumental, the synth parts below where recorded using a single output from a microkorg so you will notice its mono and only coming from the left side of the speaker. (best to listen with headphones)

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So to illustrate the perception of distance and localisation I attempted to turn the track into a binaural recording, although this may not be a true binaural recording I've clearly been inspired by the concept. I have used the brauer motion plugin from waves on all 3 mono synth parts.

If you listen to the track below you will hear the synth parts now panning, not just left to right but they have the feel of moving all around your head, at some points the sound seems to be coming from behind or in front you, this is because the plugin I have used isn't just moving the sound from side to side it is also effecting the volume as it moves which is playing a trick on the brain and giving the impression of different distances so we've ended up with a sound orbiting effect so to speak. (again listen with headphones)

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From carrying out research into the human ear I have to say that I have a new found appreciation for it, I always protected my ears because they where important to me but there isn't enough said about how important they are.

Most people are under the impression that we hear with our ears, that they are just for listening for the gaps so we can talk again and that's it, but its so much more than that, our ears enable us to decipher the location of sounds, like when we are crossing the road for example, the ability to hear doesn't just give us the pleasure of music but also the warning of danger, they are one of our most overlooked survival tools.

I've also realised that awareness of hearing damage is not as wide spread as it should be and there should be more done to publicise the dangers. Ears are a gift but can quickly become a curse like a rotting tooth if they aren't looked after, as was the tragic case of my friend with tinnitus.
The information I have gathered from the musicians union has been extremely useful and I would hope that many musicians will take advantage of the offer to protect their hearing

Most of all my research into binaural recording and our ability to hear from all angles has influenced the way I will produce music from now on, the new found ability to shift sounds around the listeners head while they are listening to a track has the power to transform a piece of music from mundane to extraordinary. I have a much clearer understanding of how the ear works in relation to sound localisation from using the brauer motion plugin and my own research into inter aural delay and intensity, this will benefit my own sound design and production techniques.

Heres hoping I can hold on to my hearing a bit longer.

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https://www.hearinglink.org/your-hearing/how-the-ear-works/
https://www.mayoclinic.org/diseases-conditions/hearing-loss/symptoms-causes/syc-20373072
https://www.everydayhealth.com/senior-health/how-to-prevent-hearing-loss.aspx
www.helpmusicians.org.uk
https://www.hearformusicians.org.uk
https://en.wikipedia.org/wiki/Sound_localization#How_sound_reaches_the_brain
http://www.dangerousdecibels.org/virtualexhibit/2howdowehear.html
http://www.hearingcareblog.com/2013/05/21/the-inner-workings-of-the-human-ear-form-and-function/
https://en.wikipedia.org/wiki/Vestibular_membrane