Voice activity detector for speech signals in variable background noise
First Claim
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1. A method of detecting voice activity in received voice signal samples including background noise, comprising the steps of:
- deriving voice signal parameters from the voice signal samples, wherein the voice signal parameters include an average signal level, calculated as a short-term average energy of the voice signal samples, and a slope, calculated as an absolute value of a change in the average signal level;
comparing the voice signal parameters with voice signal parameter thresholds and setting a Voice Activity Detection (VAD) flag according to the results of the comparisons;
updating the voice signal parameter thresholds at a first frequency to ensure rapid tracking of the background noise if the VAD flag is not set; and
updating the voice signal parameter thresholds at a second slower frequency for slower tracking of the background noise if the VAD flag is set.
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Abstract
A voice activity detector (VAD) which determines whether received voice signal samples contain speech by deriving parameters measuring short term time domain characteristics of the input signal, including the average signal level and the absolute value of any change in average signal level, and comparing the derived parameter values with corresponding thresholds, which are periodically monitored and updated to reflect changes in the level of background noise, thereby minimizing clipping and false alarms.
184 Citations
20 Claims
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1. A method of detecting voice activity in received voice signal samples including background noise, comprising the steps of:
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deriving voice signal parameters from the voice signal samples, wherein the voice signal parameters include an average signal level, calculated as a short-term average energy of the voice signal samples, and a slope, calculated as an absolute value of a change in the average signal level; comparing the voice signal parameters with voice signal parameter thresholds and setting a Voice Activity Detection (VAD) flag according to the results of the comparisons; updating the voice signal parameter thresholds at a first frequency to ensure rapid tracking of the background noise if the VAD flag is not set; and updating the voice signal parameter thresholds at a second slower frequency for slower tracking of the background noise if the VAD flag is set. - View Dependent Claims (2, 3, 4, 5)
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6. A voice activity detector for detecting voice activity in received voice signal samples including background noise, comprising:
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a calculator for calculating voice signal parameters from the voice signal samples, the voice signal parameters including; an average signal level, calculated as a short-term average energy of the voice signal samples; and a slope, calculated as an absolute value of a change in the average signal level; a comparator for comparing the voice signal parameters with voice signal parameter thresholds, wherein a Voice Activity Detection (VAD) flag is set based on the comparisons; and an updater for updating the voice signal parameter thresholds at a first frequency to ensure rapid tracking of the background noise if the VAD flag is not set, and updating the voice signal parameter thresholds at a second slower frequency for slower tracking of the background noise if the VAD flag is set. - View Dependent Claims (7, 8, 9, 10)
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11. A memory device storing instructions to be implemented by a data processor in a communications system, for detecting voice activity in received voice signal samples including background noise, the instructions comprising:
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instructions for deriving voice signal parameters from the voice signal samples, wherein the voice signal parameters include an average signal level, calculated as a short-term average energy of the voice signal samples, and a slope, calculated as an absolute value of a change in the average signal level; instructions for comparing the voice signal parameters with voice signal parameter thresholds and setting a Voice Activity Detection (VAD) flag according to the results of the comparisons; instructions for updating the voice signal parameter thresholds at a first frequency to ensure rapid tracking of the background noise if the VAD flag is not set; and instructions for updating the voice signal parameter thresholds at a second slower frequency for slower tracking of the background noise if the VAD flag is set. - View Dependent Claims (12, 13, 14, 15)
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16. A voice activity detector for detecting voice activity in received voice signal samples comprising:
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means for deriving voice signal parameters from the voice signal samples, including means for calculating an average signal level as a short-term average energy of the voice signal samples, and means for calculating a slope as an absolute value of a change in the average signal level; means for comparing the voice signal parameters with voice signal parameter thresholds; means for setting a Voice Activity Detection (VAD) flag according to the results of the comparisons; means for updating the voice signal parameter thresholds at a first frequency to ensure rapid tracking of the background noise if the VAD flag is not set; and means for updating the voice signal parameter thresholds at a second slower frequency for slower tracking of the background noise if the VAD flag is set. - View Dependent Claims (17, 18, 19, 20)
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Specification