Speech Enhancement Using Multiple Microphones.
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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A new application of Widrows Adaptive Noise Cancelling ANC algorithm is presented. Specifically, the ambient environment is generalized to include the case where an acoustic barrier exists between the primary and reference microphones. By updating the coefficients of the noise estimation filter only during silence, it is shown that the ANC technique can provide substantial noise reduction with little speech distortion even when the acoustic barrier provides only moderate attenuation of acoustic signals. The use of the modified ANC method is evaluated using an oxygen facemask worn by fighter aircraft pilots. Experiments demonstrate that if a noise field is created using a single source, 11 dB signal-to-noise ratio improvement can be achieved by attaching the reference microphone to the exterior of the facemask. The length of the ANC filter required for this particular environment is only about 50 points long.
- Electrical and Electronic Equipment
- Non-Radio Communications