Electrical audio signal processing systems and devices – One-way audio signal program distribution – Public address system
Patent
1988-02-03
1990-09-25
Harkcom, Gary V.
Electrical audio signal processing systems and devices
One-way audio signal program distribution
Public address system
G10L 702
Patent
active
049598651
ABSTRACT:
A voice operated switch employs digital signal processing techniques to examine audio signal frames having harmonic content to identify voiced phonemes and to determined whether the signal frame contains primarily speech or noise. The method and apparatus employ a multiple-stage, delayed-decision adaptive digital signal processing algorithm implemented through the use of commonly available electronic circuit components. Specifically the method and apparatus comprise a plurality of stages, including (1) a low-pass filter to limit examination of input signals to below about one kHz, (2) a digital center-clipped autocorrelation processor whih recognizes that the presence of periodic components of the input signal below and above a peak-related threshold identifies a frame as containing speech or noise, and (3) a nonlinear filtering processor which includes nonlinear smoothing of the frame-level decisions and incorporates a delay, and further incorporates a forward and backward decision extension at the speech-segment level of several tenths of milliseconds to determine whether adjacent frames are primarily speech or primarily noise.
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Adlersberg Shabtai
Aizner Mendel
Stettiner Yoram
Harkcom Gary V.
Merecki John A.
The DSP Group Inc.
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