D/deaf- A concept signifying the cultural identity many Deaf people feel. Those using sign language and feeling alliance to the Deaf community will use a capital 'D' when describing themselves. Those who see deafness simply as a description of hearing ability will use a lowercase 'd' to describe themselves.

Deaf Community- The group of hearing and Deaf people who use and promote Sign Language and who have common goals and values.

Deaf Culture- The culture of the Deaf, based on Sign Language and a common heritage.

Decibel- The unit used when measuring sound intensity. Usually abbreviated as dB.

Developmental Age- The age of a child corrected to indicate their function in language, motor skills, and intelligence, as compared to other children.

Disability- The currently accepted term for a person with reduced function of some sense or mental process. Replaces the term handicap.

Due Process- The process available to parents who wish to challenge the proposed plan of the Committee on Special Education.

Ear- The organ of hearing.

Eardrum- A thin membrane between the outer and middle ear which vibrates in response to sound waves in the air.

Earmold- The custom molded component of a BTE hearing instrument which delivers amplified sounds into the ear.

Eustachian Tube- The tube connecting the middle ear to the back of the nose which controls air pressure behind the eardrum.

Feedback- The whistle that comes from an improperly fitted earmold or malfunctioning hearing instrument.

FM System- One type of Assistive Listening System that uses FM radio waves to carry the speaker's voice to the listener.