Patent ID: 8396707

Claim:
A method for coding an input sound signal in at least one lower layer and at least one upper layer of an embedded codec, comprising: in the at least one lower layer, (a) coding the input sound signal to produce coding parameters, wherein coding the input sound signal comprises producing a synthesized sound signal; computing an error signal as a difference between the input sound signal and the synthesized sound signal; calculating a spectrum related to the input sound signal and comprising maxima and minima; calculating, from the spectrum, a spectral mask structured to lower energy in spectral regions corresponding to the minima of the spectrum; in the at least one upper layer, (a) coding the error signal to produce coding coefficients, (b) applying the spectral mask to the coding coefficients thereby lowering an energy of the coded error signal in the spectral regions corresponding to the minima of the spectrum, and (c) quantizing the masked coding coefficients, wherein applying the spectral mask to the coding coefficients thereby lowering the energy of the coded error signal in the spectral regions corresponding to the minima of the spectrum reduces a quantization noise produced upon quantizing the coding coefficients.