Electrical compensation of the microphone sensitivities in a dual microphone directional hearing aid
Stephen C. Thompson · The Journal of the Acoustical Society of America · 1999
Hearing aids with directional sensitivity have shown enhanced user satisfaction for their improved performance in noisy environments. One way to achieve the directional response patterns is to use two omnidirectional microphones with the necessary beamforming electronics to form a beam with the desired directionality. Proper operation of the beamforming circuitry requires that the frequency-dependent sensitivities of the two microphones be accurately matched, or corrected, in both magnitude and phase. This paper presents a method of electrically compensating the response of the two microphones to provide an accurate match for beamforming without the need for special sorting of the pairs for matched response. The circuit is suitable for field recalibration if aging causes the sensitivities to vary, and can also be implemented as an adaptive circuit to update the compensation parameters with time for any slow drift with time.