A method for indicating the presence of speech in an audio signal
US4959865A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 1988 |
| Grant date | Sep 25, 1990 |
| Priority date | — |
| Expiry date | Feb 3, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L21/04
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.