JND's in the LPC poles of speech and their application to quantization of the LPC filter

For the purpose of guiding a pole quantization scheme, a psychophysical experiment was performed to measure just-noticeable differences (JND) in the frequency and radius of the poles. The frequency JNDs, measured up to a formant frequency of 4 kHz, are quantified as distributions with means that are increasing functions of formant frequency and bandwidth. An example of a pole quantization scheme, based on the JND data, is presented and found to be significantly superior to common scalar quantization methods of the LPC-PARCOR coefficients. The pole quantization scheme is found to be almost comparable, both in quality and bit consumption, to vector quantization