Low bit rate speech coding with glottal linear prediction

A coding method, glottal linear prediction, that is based on a more precise model is introduced. According to this model, speech production can be separated into three processors: the glottal excitation, the vocal tract, and the lip radiation effect. The application of the idea in the coding of telephone-line PCM (pulse-code modulation) speech that includes different types of utterances is emphasized. The only filter that has to be transmitted from the coder to the decoder is the filter which models the vocal tract. This is usually of lower order than LPC (linear predictive coding) filters used in conventional linear predictive analysis. The excitation signal is coded by modeling the obtained glottal wave estimate with Lagrange interpolation or by generating noise. Preliminary results indicate that the more accurate modeling of the speech-production mechanism will lead to improved quality in speech coding.>