Ringing in the ears

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Dr Jekyll

Original Poster:

23,820 posts

268 months

Monday 23rd August 2010
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What causes it? I know it's the result of loud noise and a sign that your ears are damaged. But what is the mechanism that causes damaged ears to ring?

Number 8

87 posts

200 months

Tuesday 24th August 2010
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The correct term is 'Tinnitus' and it can be any sort of persistant or temporary noise within the ear or both ears (e.g. buzzing, pulsating, . It's not just casued by loud music, but can also be caused by a plethora of other symptoms including excessive ear wax, high/low blood pressure, allergies, thyroid problems, injuries to the neck or head, cancer, diabetes etc. The list goes on.

From a physiological perspective tinnitus can arise in the outer ear, middle ear, inner ear and the brain. All forms of tinnitus typically result in hearing loss. Tinnitus normally resolves itself (which is obviously the case if the cause of the problem is temporary). If you go into an isolation booth there are naturally occurring sounds that exist "within" your head/ear such as the circulation of blood to the head (that sound you hear when you put a shell to your ear is exactly that). Wax and other foreign bodies will exacerbate these naturally occurring sounds, but we generally do not notice these normal sounds because of constant background noise.

One of the most common causes of tinnitus is damage to the microscopic endings of the hearing nerve in the inner ear. Advancing age is generally accompanied by a certain amount of hearing nerve impairment, and consequently tinnitus. Today, loud noise exposure is a very common cause of tinnitus, and it often damages hearing as well. Some medications (for example, aspirin) and other diseases of the inner ear (Meniere's syndrome) can cause tinnitus.

Nerve stimulants such as caffeine will highten the tinnitus.

I hope this helps somewhat.

Dom


Number 8

87 posts

200 months

Tuesday 24th August 2010
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Apologies, I think I missed your point somewhat.

Ringing in the ears is typical of noise damage, so let me explain what that damage is and why this results in "ringing" within the ears:

There are thousands and thousands of minute hair cells in the cochlea that are stimulated by the pressure of sound waves. The stimulation causes movement of these tiny hairs (think of wheat in a field moving in time to the wind blowing). When a sound is detected in the inner ear (cochlea), these tiny auditory hairs move, electrical impulses are discharged through the auditory nerve which the brain interprets as sound.

These tiny hair cells and the tiny auditory nerves are extremely delicate and are easily damaged. Prolonged exposure to loud music will damage these delicate hairs.

The reason loud music damages these hairs is because they can only withstand so much pressure and vibration and eventually will break-up/deteriorate. Typically, it is the upper register of your hearing range that is damaged because these hairs are finer than those that detect lower freuencies. Hairs are also conical shaped so the finer ends will be damaged first and these are responsible for picking-up the higher frequencies. It also explains why that "ringing" noise is generally high-pitched, because it is the physiology of those hairs that have been damaged that will then send the incorrect/misinterpreted or 'phantom sound' information to the brain via the cochlear nerve.

A hard blow to the head can also have a similar effect!

Dom

Dr Jekyll

Original Poster:

23,820 posts

268 months

Tuesday 24th August 2010
quotequote all
Thanks for that, I wondered why higher frequencies are affected more.

There was a suggestion on wikipedia that when the cells attached to the hairs detect movement they also cause the hairs to vibrate more, as an internal amplifier. So when the cells can't detect the sound properly they don't know when to stop and effectively get turned up to 11. But presumably if the hairs themselves are damaged this can't be it.

Number 8

87 posts

200 months

Wednesday 25th August 2010
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Volume is registered as a direct result of air pressure within the ear canal. A very loud speaker will force more air outwards (as you may have experienced at a loud gig/concert standing next to the stack of speakers)

I'm now going beyond the realms of what I know, but the cells within the hairs may vibrate (not sure if they act as an internal amplifier), but I would imagine if these cells are damaged then the brain may try and compensate by 'turning-up' the responsiveness of those cells or at least the signal those cells send to the brain to compensate for the damage and resultant loss in sensitivity.

E21_Ross

35,699 posts

219 months

Wednesday 25th August 2010
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there are probably hundreds of causes for this, among the reason listed, damage to the vesitbular nerve is one, or damage/infection etc etc to any part of the "neurological pathway of sound" damage or tumour etc to the part of the temporal lobe in the brain relating to hearing (e.g. primary auditory cortex).

if it's bugging you, best see your GP to see if they can diagnose the problem and see if it's nothing serious. 99/100 it's not.