Speech recognition in noisy environments with the aid of microphone arrays

Abstract This paper presents a microphone array adaptive beamformer with a dual function. The noise enhanced output is suited to transmission as well as to use as input to speech recognition systems. The areas of use envisaged are the car. the factory floor and noisy offices. The underlying structure is a steered Griffiths-Jim beamformer, with an added speech detection switch for the selective adaptation of both sections. This beamformer is effective in suppressing both stationary and non-stationary interference and is therefore a preprocessor for a wider range of speech recognition applications than any single channel noise suppression scheme could handle. Experiments were performed in a reverberant room with a 4-microphone array. Typical SNR improvements for communication purposes range from 4 to 12 dB. The effective SNR improvement for speech recognition purposes ranges from 4 to 8 dB.