The main components of a hearing aid are a microphone, an amplifier, a loudspeaker (receiver), a battery and a telecoil.
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The hearing aid microphone picks up sounds and converts them to electrical signals. From the microphone, the signals are sent on to the amplifier of the hearing aid.
TECHNICAL DESCRIPTION:
The microphone converts acoustic energy into electrical energy.
A microphone is basically a membrane which vibrates in response to the wave of compression and expansion of air molecules coming from a sound source.
As the membrane vibrates, it creates electrical energy that corresponds to the amplitude, frequency and phase of the acoustic signal. This energy is amplified before it is filtered, and amplified further in the electronic circuit of the hearing aid.
The amplifier increases the level of the electrical signal that is delivered to the hearing aid’s receiver. More amplification is provided at frequencies with more hearing loss and less amplification at frequencies with less loss.
The sound enters the amplifier in the form of electrical signals from the microphone and is sent to the hearing aid receiver via the amplifier.
TECHNICAL DESCRIPTION:
The amplifier contains most of the hearing aid’s electronic components and circuits.
The microphone delivers the signal to the amplifier, where it is processed and amplified according to the user’s amplification needs and the hearing aid setting.
The amplified signal then continues on to the hearing aid receiver, which delivers it to the user’s ear, near the ear drum.
The hearing aid receiver changes electrical signals (from the hearing aid amplifier) back into sound that can be heard by the user.
In principle, it is comparable to a loudspeaker in a radio transmitting music or speech.
The hearing aid battery delivers power to the electronic parts of the instrument. The performance of modern, digital hearing aids is very dependent on the batteries’ properties. It is therefore important to use top quality batteries to get the full benefit of the hearing aid.
The telecoil is an integral part of the hearing aid.
Some places with a lot of background noise – such as cinemas, churches, theatres and lecture rooms - are equipped with a loop system.
It is possible to connect to such a loop system by placing the program switch on the hearing aid in position “T” (telecoil).
The hearing aid program switch can be set in three different positions: M-T-MT depending on whether you wish to listen via the microphone or the telecoil. The standard setting is “M”.
“M” (microphone): For normal use, the switch should be in position “M”. Here you listen via the hearing aid’s microphone.
“T” (telecoil): Position “T” cuts off the microphone and brings the built-in telecoil into operation. The signals are then transmitted directly to the hearing aid without interference from surrounding sounds.
“MT” (microphone+telecoil): If you want to listen both via the microphone and the telecoil, place the switch in position “MT”, e.g. when watching TV while still wanting to hear the doorbell, telephone, or other people speaking.
SEE ALSO:
Loop systems
