A microprocessor-based noise cancellor for the cockpit

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A microprocessor-based noise cancellor for the cockpit

Vemula, R. / Lee, E.

The cockpit noise level can be as high as 120 dB SPL, resulting in a loss of intelligibility in voice communications and also degradation of performance of any speech recognition equipment operating in the cockpit. Moreover, the noise causes fatigue and can also result in hearing loss for the crew members. A low-cost electronic noise cancellation circuit is highly desirable to rectify these problems. The noise cancellation circuit takes noisy speech as input, reduces the intensity of noise, and returns cleaner speech which is passed to the crew member or the speech recognition equipment. A TMS320 microprocessor-based noise cancellation circuit has been developed at Telephonics using a lattice filter with proprietary adaptive control mechanism. The circuit has been tested with various real-world noises, such as those generated in UH1H, CH47C, UH60A and Apache helicopters, and also with noises synthesized in the lab, such as power line interference and pink noise. Test results indicate that the circuit provides 6 to 18 dB noise reduction with no perceivable distortions to speech sounds.