A simple modification to facilitate robust generalized sidelobe canceller for hearing aids

Abstract

This work focuses on an adaptive beamformer in a hearing aid application using a generalized sidelobe canceller structure (GSC). In this application, the constraint and blocking matrices in the GSC structure are specifically designed using an estimate of the transfer functions between the target source and the microphones to ensure optimal beamformer performance. We show that, in practice, the GSC always—unintentionally—attenuates the target sound in a special but realistic situation where all signals, including the target and noise signals, originate from the look direction reflected by the look vector. This happens because, in practice, the blocking matrix in the GSC structure is non-ideal. We introduce a simple modification to the GSC structure, which solves the problem of undesired target signal attenuation in situations where all signals originate from the look direction. Furthermore, this modification can also prevent desired signals, originating from positions spatially close to the look direction, to be removed. We also show that the solution has no impact on other acoustic situations.