Multichannel Threshold Audio-Noise-Reduction Circuit
Edward S. Rogers · The Journal of the Acoustical Society of America · 1963
The object of this research has been to investigate the possibility of developing a noise-reduction circuit that could extract speech intelligence from a signal in which the intelligence was masked by noise. The problem has been attacked experimentally by building a 110-channel threshold noise-reduction circuit. Each channel contains bandpass filters and a nonlinear device to improve the signal-to-noise ratio in the channel. A number of tests have been performed to evaluate the circuit. The results show that the threshold noise reducer is capable of improving the over-all signal-to-noise ratio of a noisy speech signal, and it is capable of separating some speech components from noise. However, the operational effectiveness of the device for the improvement of speech intelligence is marginal.