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 (SNR) speech signals can significantly improve communication as well as enable the use of speech-based alertness detection methods. Acoustic beamforming utilizes 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 in a green truck cabin has been successful, even with very high levels of noise.
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