The ear is composed of three parts :the internal,middle and inner you use all of them in hearing.
The variety of conditions that may affect of ear and cause deafness are:
1.Heredity, due the heredity problem for example if my grand mother is having a hearing problem there are conditions I may get that problem too.
2.Diseases such as ear infections and meningitis.
3.Long term exposure of loud noise.
And many more these are very common in many people.There are two types of hearing loss.One happens when the inner ear or the auditory nerve get's damaged.
This type is usually permanent.The other kind happens when sound waves can't reach the inner ear.Ear wax build up or punctured ear can cause it.

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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...
    1    The outer ear consists of the pinna, ear canal and eardrum
     2    The middle ear consists of the ossicles and ear drum
     3   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 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..........................................

hope its help u............

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