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The ear consists of three parts that each have a role in hearing. Sound waves enter the ear canal of the external ear to cause the tympanic membrane (eardrum) to vibrate. Within the middle ear there are three small bones, the malleus (hammer), incus (anvil) and the stapes (stirrup). These bones continue to transmit the vibrating signal from the eardrum to the cochlea (inner ear), which is a fluid filled chamber. The movement of the middle ear hearing bones causes the inner fluids to move in waves. These waves stimulate the hair cells of the inner ear. The movement of the hair cells then stimulates the auditory nerve which carries the signals to the brain allowing us to hear.
Hearing loss is considered to be either conductive or sensorineural. Conductive hearing loss occurs when there is a problem in external or middle ear. This type of hearing loss is often correctable with either surgery or a hearing aid. Sensorineural hearing loss occurs when there is a problem affecting the cochlea or auditory nerve. Hearing aids are most often used to correct this type of hearing loss. When hearing is so poor that hearing aids are of little or no benefit, a cochlear implant may be considered.