User determined superdirective beamforming

Abstract

Superdirective beamforming is a well-known method for enhancement of reverberated speech signals. Nevertheless, it is very susceptible to errors in the sensor array characteristics, thermal noise, and white noise input, resulting in a low level of white noise gain, particularly at low frequencies. It is of great interest to develop a beamformer with superior enhancement of reverberated signals, having a high directivity factor, together with a relatively high white noise gain level. In this paper, a solution which controls both the directivity factor and the white noise gain is examined. We propose a linear weighted combination of two conventional beamformers, the regularized superdirective beamformer and the delay-and-sum beamformer. We analyze the beamformer gain responses, and consequently derive two user-determined frequency-dependent white noise gain and directivity factor beamformers, respectively. Simulation results approve our findings, and show of a robust user-controlled solution, with an effective tradeoff between the performance measures of the beamformer.