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The Ear Anatomy and Physiology
The ear is divided into 3 different parts:
External Ear - consists of a “cup like” structure call the Pinna, which by the nature of how it is shaped is designed to collect and direct incoming sound into the external ear canal. The ear canal transmits sounds to the eardrum or tympanic membrane.
Middle Ear - begins with the tympanic membrane which is a very thin, tense membrane. It vibrates when sound waves hit it. The vibration of the membrane then causes vibration of three tiny bones in the middle ear called the Malleus (hammer), Incus (anvil), and Stapes (stirrup). Vibrations of the tympanic membrane travel to the third part called the inner ear. The Eustachian tube is also part of the middle ear system. This tube connects the back of the throat (nasopharynx) to the middle ear. The primary functions of the Eustachian tube are (1) it serves to keep the middle ear pressure equal to the pressure in the outside atmosphere and (2) to permit drainage of normal and diseased middle ear secretions from the middle ear to the back of the throat (nasopharynx).
Inner Ear - is divided into the cochlea, the vestibule, and the auditory nerve. The cochlea and auditory nerve are the portions we are concerned with when discussing amplification. The cochlea is a “snail shell” looking organ that is filled with fluid and thousands of tiny “hair cells”. When the vibrating middle ear bones cause waves in the cochlear fluid, this in turn becomes electrical stimulation that is transmitted to the auditory nerve and then to the hearing centers in the brain.
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