Microphone Directionality - Interacoustics Affinity 2.0 Additional Information

2.0
Affinity Additional Information Page 286
3.7.9

Microphone Directionality

Unwanted noise is provided by many different sources in many daily life situations. They can come from
different directions due to position or reflection from the walls in the environment. Fortunately many digital
hearing aids have directional microphones that suppress noise coming from 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.
2.0
This effect can be measured in the Affinity test chamber.
The two loudspeakers in each side of the test chamber are used. First a frequency response is recorded for
sounds coming from one side. After this a similar curve will be recorded for sounds coming from the other
side. Then the second curve is subtracted from the first and results in the directionality curve.
2.0
is used for directionality testing the small size of this
Note: When the built-in test chamber of the Affinity
chamber will of course have a considerable effect on the directionality results. Under such circumstances the
test results will be different from results obtained in manufacturer's huge fully damped anechoic rooms.
2.0
To obtain the best results with the Affinity test chamber from this test, allow the lid to be open during the
test. As stimuli are relatively strong for such tests, and as the test is being carried out in the 1kHz to 4kHz
range only, this will be possible in most office environments.
This way you can get a test of how the hearing aid directionality functions under these conditions. If you
repeat the test with the hearing aid and the reference microphone in the exact same position (very
important), then the test results will be duplicated. This means that you can use the test to verify that the
directionality is unchanged over time, when you repeat the test at any later time. This can be good
verification from a technical stand point as well as in convincing a client that hearing aid directionality
function has remained unchanged.
Below is an example:
View directionality details
Front microphone response
Back microphone response
Directionality
Select test
.