Patent ID: 6792405
Filing Date: 2004-09-14
Classification: G10L

Abstract:
An automatic speech recognition system for receiving as an input a coded bitstream speech signal and generating therefrom feature recognition parameters, said recognition system includinga spectral envelope detection arrangement for generating features derived from line spectrum pair (LSP) information from the encoded bitstream; and an excitation signal extraction arrangement for generating features derived from adaptive codebook gain and fixed codebook gain information related to voiced and unvoiced information, respectively, wherein the bitstream is defined on a frame-by-frame basis, each frame including a first set of bits associated with spectral envelope detection and the LSP coefficients and a second set of bits associated with the excitation signal extraction and the voiced/unvoiced feature parameters, the second set of bits within each frame being divided into subframes, with an adaptive gain coefficient and a fixed gain coefficient calculated for each subframe, the adaptive gain coefficient defined by: ACG&it;(i)=&Sum;k=01&it;gp2&it;(2&it;i+k),i=0,1and the fixed gain coefficient is defined by: FCG&it;(i)=Î³10&it;â€ƒ&it;log10&it;{&Sum;k=01&it;gc2&it;(2&it;i+k)},i=0,1.