An Automotive three-microphone Voice Activity Detector and noise canceller

This paper addresses issues in improving hands-free speech recognition performance in car environments. A three-microphone array has been used to form a beamformer with normalised least-mean squares (NLMS) to improve Signal to Noise Ratio (SNR). The array has been implemented with a Voice Activity Detector (VAD) which uses time-delay estimation together with magnitude-squared coherence (MSC). An experiment clearly shows the ability of the composite system to reduce noise outside of a defined active zone.