Ear Plate - the outer portion of an ear mold.

Ear Wax - yellow secretion from glands in the outer ear (cerumen) that keeps the skin of the ear dry and protected from infection.

Endolymph - fluid in the labyrinth (the organ of balance located in the inner ear that consists of three semicircular canals and the vestibule).

Feedback - A common problem in older hearing aids. When an object is held too close to the hearing aid, sound bounces back and forth between the object and the aid, resulting in a loud squealing noise. It's very painful to the user. Some newer models are programmed to minimize this effect.

Frequency - The rate of the vibrations in a sound wave. Frequency is measured in hertz, which is expressed as cycles per second.

Frequency Control - Controllers used to fine tune the responses of a hearing aid.

Frequency Response - A measure of how a hearing aid responds to sounds in an environment. It is shown graphically on a Frequency Response Curve.
Gain: A measure of the effectiveness or strength of a hearing aid.

Hair Cells - sensory cells of the inner ear, which are topped with hair-like structures, the stereocilia, and which transform the mechanical energy of sound waves into nerve impulses.

Hearing - series of events in which sound waves in the air are converted to electrical signals, which are sent as nerve impulses to the brain, where they are interpreted.

Hearing Aid - electronic device that brings amplified sound to the ear. A hearing aid usually consists of a microphone, amplifier, and receiver.

Hearing Disorder - disruption in the normal hearing process that may occur in outer, middle, or inner ear, whereby sound waves are not converted to electrical signals and nerve impulses are not transmitted to the brain to be interpreted.

Hearing Loss Levels: Hearing loss is identified as ranging from Mild to Profound.  The typical guidelines are: Mild hearing loss (Average from 25db to 40db); Moderate (Average from 40db to 55db); Moderate/Severe (Average from 55db to 70db); Severe (Average from 70db to 90db) and Profound (Average greater than 90db). This does not have to be an across the board classification, though. I have a Profound loss in some frequencies, Severe in others, and Mild to Normal in some very low frequencies.