Patent ID: 6381570
Filing Date: 2002-04-30
Classification: G10L

Abstract:
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: Evoice, n=(1-&agr;voice)*Evoice,nâˆ’1+&agr;voice*En, where Evoice, n is said voice energy estimation value for said current block period, &agr;voice is a voice time constant, Evoice, nâˆ’1 is said voice energy estimation value for an immediately preceding voice block period, and En is said current block energy; andsaid noise energy estimation value Enoise is updated according to the formula: Enoise, n=(1-&agr;noise)*Enoise,nâˆ’1+&agr;-noise*En, where Enoise,n is said noise energy estimation value for said current block period, &agr;noise is a noise time constant, Enoise, nâˆ’1 is said noise energy estimation value for an immediately preceding noise block period, En is said current block energy.