The noisy and monotonous environment of a locomotive cabin is certainly not conducive to clear communication or to high levels of crew alertness. Both of these problems have a negative impact on the operational safety of the locomotive. In this paper, an acoustic beamforming system is developed and evaluated for enhancing the speech signals measured in a locomotive cabin. Higher signal-to-noise ratio speech signals can significantly improve communication as well as enable the use of speech-based alertness detection methods. Acoustic beamforming utilises a spatially distributed array of low-cost microphones permanently mounted in the locomotive cabin trim, with a digital signal processing algorithm to effectively create a focused directional microphone which can be pointed at any crew member in the cabin. Preliminary experimental testing of this system has been successful, even with very high levels of noise. The experimental results clearly indicate that fixed parameter filters can be trained to generate a focused acoustic beam that provides significant noise reduction. In fact, almost equivalent performance was obtained experimentally using only four microphones in the beamformer array. Future work will include an actual realtime implementation of the acoustic beamformer with multiple independent noise sources. This future evaluation will also need to include a sensitivity analysis to the location of the speech and noise sources.
Acoustic beamforming enhancement of locomotive cabin speech
2007
6 Seiten, 10 Bilder, 7 Quellen
Conference paper
English
JRC/ICE2007-40102 Acoustic Beamforming Enhancement of Locomotive Cabin Speech
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