Understanding Hearing Aids

While there are several types and many brands of hearing aids, they all share some common features. Below is an exploded view of a typical Behind-The-Ear (BTE) hearing aid. The parts are as follows:

A	Function Switch: Usually M-T-O (Microphone, Telecoil and Off)
B	Battery: Supplies power to the amplifier
C	Microphone: Converts acoustic energy to electrical energy.
D	T-Coil: Converts magnetic energy to electrical energy.
E	Amplifier or Circuit: Increases the strength of the electrical signal. Also filters and modifies the response of the hearing aid to match the hearing loss of the user.
F	Volume (Gain) control. Allows the user to increase or decrease the over-all level of the sound after the amplifier. Many newer hearing aids have automatic gain control.
G	Receiver: Converts electrical energy to acoustic energy.
H	Sound hook (tonal tube): Delivers the sound from receiver to the earmold. May be filtered to further adjust the signal to match the hearing loss.