The basics of hearing
To better comprehend whatever issue you are experiencing with your hearing, it helps to understand the basics of the ear’s anatomy and how sound is transmitted as it travels to the brain.
The ear is comprised of three parts. The outer ear captures sound waves and directs them through the ear canal to the eardrum, or tympanic membrane. The middle ear contains the three bones, or ossicles, referred to as the hammer, anvil and stirrup. The medical terms for these bones are the malleus, incus and stapes. The middle ear, which is filled with air, opens into the inner ear, which is filled with fluid, where sound is transmitted to the hearing organ, or cochlea within the inner ear. The inner ear also contains the organs within the labyrinth or vestibular system, which helps to maintain your balance.
As sound passes through the eardrum and ossicles to the inner ear, the sound waves are converted into electrical impulses that are transmitted along the cochlear nerve to the brain, which then interprets the sound.
Problems can develop in any or all of the parts of the ear. The type of hearing loss you experience is classified by the location of the problem, whether it is with the outer, middle or inner ear. The type of hearing loss determines your course of treatment.
If the problem arises from an abnormality with the outer or middle ear, it is called a conductive hearing loss. This type of hearing impairment generally involves difficulty with conducting sound from the middle ear to the inner ear. Examples of conductive hearing impairments include the absence of the outer ear (atresia) or the ear canal (microtia), otosclerosis or problems with the hearing bones, and fluid in the middle ear due to an ear infection.
A problem in the inner ear, whether it involves the cochlea or cochlear nerve, is classified as a sensorineural hearing impairment. Examples of this type of hearing impairment include presbycusis, the degeneration of the cochlear nerve that occurs as people age, or sudden hearing loss stemming from inflammation.
Mixed hearing loss results from problems in both the middle and inner ear. Chronic ear infections and otosclerosis can result in mixed hearing loss.