Adaptive two-threshold method for discriminating noise from speech in a communication signal
First Claim
1. A method of discriminating noise and voice energy in a communication signal, comprising the steps of:
- for a plurality of block periods;
sampling said signal a number of times to obtain sample values;
calculating a block energy value for said signal by summing the squares of said sample values from said number of samples; and
for an update period equal to a sum of said plurality of block periods;
assigning a maximum block energy value calculated during said update period to a variable Emax;
assigning a minimum block energy value calculated during said update period to a variable Emin;
calculating a noise energy threshold value based on the relative values of Emax and Emin, wherein between a first upper bound and a first lower bound said noise energy threshold may assume a continuum of values;
calculating a voice energy threshold value based on the relative values of Emax and Emin, wherein between a second upper bound and a second lower bound said voice energy threshold may assume a continuum of values; and
updating said noise energy threshold and said voice energy threshold in accordance with said calculations for their respective values;
said voice energy estimation value Evoice is updated according to the formula;
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Abstract
A method of discriminating noise and voice energy in a communication signal. A signal is measured in a plurality of block periods, which are sampled to obtain a measurement of the block energy value for the signal. The blocks are compared to a noise threshold and to a voice threshold to discriminate between noise and voice. The thresholds for noise and voice are periodically updated based on the minimum and maximum energy levels measured for block energies. In a preferred embodiment, the voice energy threshold and noise energy threshold values are updated according to a formula where the revised thresholds are based upon a factor of the minimum and maximum energy levels of the current block and the most recent past block and the average energy of the previous blocks. Updating of threshold levels allows for more accurate estimation of noise and voice during changes in either noise, voice or both to avoid missclassification of noise and/or voice.
137 Citations
10 Claims
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1. A method of discriminating noise and voice energy in a communication signal, comprising the steps of:
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for a plurality of block periods;
sampling said signal a number of times to obtain sample values;
calculating a block energy value for said signal by summing the squares of said sample values from said number of samples; and
for an update period equal to a sum of said plurality of block periods;
assigning a maximum block energy value calculated during said update period to a variable Emax;
assigning a minimum block energy value calculated during said update period to a variable Emin;
calculating a noise energy threshold value based on the relative values of Emax and Emin, wherein between a first upper bound and a first lower bound said noise energy threshold may assume a continuum of values;
calculating a voice energy threshold value based on the relative values of Emax and Emin, wherein between a second upper bound and a second lower bound said voice energy threshold may assume a continuum of values; and
updating said noise energy threshold and said voice energy threshold in accordance with said calculations for their respective values;
said voice energy estimation value Evoice is updated according to the formula;
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification