Patent ID: 7013269

Claim:
A frequency domain interpolative CODEC system for low bit rate coding of speech, comprising: a linear prediction (LP) front end adapted to process an input signal providing LP parameters which are quantized and encoded over predetermined intervals and used to compute a LP residual signal; an open loop pitch estimator adapted to process said LP residual signal, a pitch quantizer, and a pitch interpolator adapted to provide a pitch contour within the predetermined intervals; and a signal processor responsive to said LP residual signal and the pitch contour and adapted to perform the following: extract a prototype waveform (PW) from the LP residual and the open loop pitch contour for a number of equal sub-intervals within the predetermined intervals; normalize the PW by said PW's gain; extract measures of periodicity from the normalized PW that are correlated to degrees of periodicity over each predetermined interval; extract measures of periodicity from open loop parameters derived from the input signal that are correlated to degrees of periodicity over each predetermined interval; and provide an overall voicing measure for each predetermined interval, said voicing measure characterizing a degree of voicing of said input signal, by combining the measures of periodicity extracted from the open loop parameters and the measures of periodicity extracted from the normalized PW over the predetermined intervals.