A two-microphone adaptive broadband array for hearing aids

We derive a two-microphone directional and adaptive broadband array for use in hearing aids. The array contains only two directional microphones to satisfy the cosmetic constraints which are most likely to be accepted by hearing aid wearers. Our proposed processing method is a modification of Widrow (1975) et al.´s narrowband MMSE algorithm which does not generate a reference signal. The required frequency separation is performed using a multirate filter bank. The distance between two microphones is 12 cm. When the signals are split into four narrower bands, an SNR improvement of 9.2 dB and an intelligibility-weighted directivity index of 8.9 dB are obtained. Only 8 weights (2 for each band) need to be updated and thus the approach is much simpler when compared with other methods