Method and system for improved discontinuous speech transmission
First Claim
1. A method of transmitting speech signals in a discontinuous transmission system, comprising the steps of:
- segmenting the speech signals into non-overlapping frames;
detecting voice activity in each of said non-overlapping frames;
classifying said each of said non-overlapping frames as either speech or noise in response to said detecting step;
if said voice activity is classified as speech, computing and transmitting parameters representing said non-overlapping frames classified as speech; and
if said voice activity is classified as noise,reclassifying a portion of said non-overlapping frames classified as noise to noise-analysis frames;
computing auto-correlation values for said noise-analysis frames;
computing a weighted average of said auto-correlation values to represent said noise-analysis flames; and
transmitting said weighted average values as noise parameters for use in generating comfort noise.
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Abstract
To overcome the problem of poor representation of the background noise, the present invention includes a noise parameter generator (40) which uses a weighted average of auto-correlation values of the input signal generated during the noise-analysis phase. The weighting function gives less weight to the auto-correlations during the first few frames (as they may contain speech) and more weight to frames towards the end of this phase. Also included, to overcome the bursty nature of comfort noise, is a comfort noise generator (50) which gradually changes the nature of the signal from speech to pseudo-random noise after the speech-burst The comfort noise generator (50) of the present invention excites the auto-regressive filter corresponding to the noise model with a weighted combination of the past excitation and pseudo-random noise.
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Citations
5 Claims
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1. A method of transmitting speech signals in a discontinuous transmission system, comprising the steps of:
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segmenting the speech signals into non-overlapping frames; detecting voice activity in each of said non-overlapping frames; classifying said each of said non-overlapping frames as either speech or noise in response to said detecting step; if said voice activity is classified as speech, computing and transmitting parameters representing said non-overlapping frames classified as speech; and if said voice activity is classified as noise, reclassifying a portion of said non-overlapping frames classified as noise to noise-analysis frames; computing auto-correlation values for said noise-analysis frames; computing a weighted average of said auto-correlation values to represent said noise-analysis flames; and transmitting said weighted average values as noise parameters for use in generating comfort noise. - View Dependent Claims (2, 3, 4, 5)
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Specification