Design of a robust multi-microphone noise reduction algorithm for hearing instruments

This paper discusses the design and low-cost implementation of a robust multi-microphone noise reduction scheme, called the Spatially Pre-processed Speech Distortion Weighted Multi-channel Wiener Filter (SP-SDW-MWF). This scheme consists of two parts: a robust fixed spatial pre-processor and a robust adaptive Multi-channel Wiener Filter (MWF). Robustness against signal model errors is achieved by incorporating statistical information about the microphone characteristics into the design procedure of the spatial pre-processor and by taking speech distortion explicitly into account in the optimisation criterion of the MWF. Experimental results using a hearing aid show that the proposed scheme achieves a better noise reduction performance for a given maximum speech distortion level, compared to the widely studied Generalised Sidelobe Canceller (GSC) with Quadratic Inequality Constraint (QIC). For implementing the adaptive SDW-MWF, an efficient stochastic gradient algorithm in the frequency-domain can be derived, whose computational complexity and memory usage is comparable to the NLMS-based Scaled Projection Algorithm for implementing the QIC-GSC.