Dealing with uncertainty in microphone placement in a microphone array speech recognition system

This paper investigates robustness to uncertain microphone placements in an array beamformer front-end to a speech recognition system. There are two general approaches to handling the placement uncertainty: using the approximately known geometry in a robust beamforming technique, or using techniques that require no prior knowledge of geometry. Experiments in this paper compare the robustness of different techniques for both of these approaches in terms of speech recognition accuracy. To benefit from existing microphone array speech recognition data corpora for experimentation, microphone placement uncertainty is simulated by introducing random perturbations in the assumed geometry. Experimental results show that robust beamforming yields stable performance to a certain degree of placement error, but thereafter techniques such as automatic calibration are beneficial.