SPEECH CODING EMPLOYING HYBRID LINEAR PREDICTION CODING

A speech coding system that employs hybrid linear prediction coding during extraction of linear prediction coefficients within ITU-Recommendation speech coding standards. The present invention is operable within linear prediction speech coding systems including code-excited linear prediction speech coding systems, and it provides for a substantially improved perceptual quality of reproduced speech signals when compared to conventional speech coding methods that employ the commonly known auto-correlation method that is based on minimizing the linear prediction coding (LPC) prediction error energy. The invention is operable to provide for high perceptual quality of reproduced speech signals having substantial differences of energy in various frequency bands. For example, for speech signals having information dispersed broadly across the frequency spectrum, such as having a significant amount of information at low frequency and a significant amount of information at high frequency, the invention provides a way to maintain a high perceptual quality across the broad frequency range. The invention generates a single set of linear prediction coefficients (LPCs) either directly from the speech signal in certain embodiments of the invention, or alternatively, interveningly through the use of line spectral frequencies (LSFs) that are generated from different sets of linear prediction coefficients (LPCs) generated from the speech signal itself in other embodiments of the invention.