Several considerations are given to insertion gains measured by body aids under different measuring conditions.
Measurment was carried out as follows:
(1) Simulated insertion gain was measured when a body aid is placed in a pocket of a man's jacket and also when the aid is set away from the jacket at intervals of 10cm toward a loudspeaker.
(2) Two types of body aids were tested.
Apertures of microphone in these aids were set in two different ways.
MODEL (A): The aperture faces both the upper side and the front of the aid.
MODEL (B): The aperture faces only the upper side of the aid.
(3) Simulated insertion gains were measured by SAMRAI with C-coupler.
(4) A microphone which has a special aperture was also tested. The structure of the microphone is equivalent to a hearing aid whose aperture faces the front.
From these measurements, it was certain that MODEL (A) is less affected by the difference of measuring conditions than MODEL (B). And the similar result to MODEL (A) is obtained from the microphone mentioned in (4).
As a result, it would be advised that a substantial aperture of a microphone for a body aid should face the front.
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