Microphone Directionality - Interacoustics Affinity 2.0 Additional Information

3.7.10 Microphone directionality

Unwanted noise is provided by many dif f erent sources in many daily lif e situations. They can come f rom
dif f erent directions due to position or ref lection f rom the walls in the environment. Fortunately, many digital
hearing aids have directional microphones that suppress noise coming f rom some directions while
maintaining a good sensitivity to sounds coming from another direction. This is done to give the user an
advantage so that they are more likely to hear the signals they want over the noise in a noisy environment.
This ef f ect can be measured in the Af f inity 2.0 test chamber.
The two loudspeakers in each side of the test chamber are used. First a f requency response is recorded f or
sounds coming f rom one side. Af ter this a similar curve will be recorded f or sounds coming f rom the other
side. Then the second curve is subtracted f rom the f irst and results in the directionality curve.
Note: When the built-in test chamber of the Af f inity 2.0 is used f or directionality testing the small size of this
chamber will of course have a considerable ef f ect on the directionality results. Under such circumstances the
test results will be dif f erent f rom results obtained in manuf acturer's huge f ully damped anechoic rooms.
To obtain the best results with the Af f inity 2.0 test chamber f rom this test, allow the lid to be open during the
test. As stimuli are relatively strong f or such tests, and as the test is being carried out in the 1kHz to 4kHz
range only, this will be possible in most of fice environments.
This way you can get a test of how the hearing aid directionality f unctions under these conditions. If you
repeat the test with the hearing aid and the ref erence microphone in the exact same position (very
important), then the test results will be duplicated. This means that you can use the test to verif y that the
directionality is unchanged over time when you repeat the test at any later time. This can be good verif ication
f rom a technical standpoint as well as in convincing a client that hearing aid directionality f unction has
remained unchanged.
Below is an example:
View directionality details
Front microphone response
Back microphone response
Directionality
Select test
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D-0004576-Q – 2022/05
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Affinity/Equinox2.0 – Additional Information