Speech endoding device

Abstract

The present invention is a synthetic speech encoding device that produces a synthetic speech signal which closely matches an actual speech signal. The actual speech signal is digitized, and excitation pulses are selected by minimizing the error between the actual and synthetic speech signals. The preferred pattern of excitation pulses needed to produce the synthetic speech signal is obtained by using an excitation pattern containing a multiplicity of weighted pulses at timed positions. The selection of the location and amplitude of each excitation pulse is obtained by minimizing an error criterion between the synthetic speech signal and the actual speech signal. The error criterion function incorporates a perceptual weighting filter which shapes the error spectrum.

1 . A method for encoding speech, the method comprising:
 sampling a speech signal to generate samples;   producing spectral representations from the samples;   performing open-loop pitch analysis based on the samples; and   transmitting encoded speech comprising a codebook index.   
   
   
       2 . The method of  claim 1 , wherein a residual signal is associated with the open-loop pitch analysis. 
   
   
       3 . The method of  claim 2 , wherein the codebook index is based on the residual signal. 
   
   
       4 . The method of  claim 1 , wherein a sampling rate of the samples is 8 kHz. 
   
   
       5 . A speech encoder comprising:
 a sampler configured to sample a speech signal to generate samples;   a linear predictive coding (LPC) device configured to produce spectral representations from the samples;   a pitch analyzer configured to perform open-loop pitch analysis based on the samples; and   a bit packing device configured to transmit encoded speech comprising a codebook index.   
   
   
       6 . The speech encoder of  claim 5 , wherein a residual signal is associated with the pitch analyzer. 
   
   
       7 . The speech encoder of  claim 6 , wherein the codebook index is based on the residual signal. 
   
   
       8 . The speech encoder of  claim 5 , wherein the sampler is configured to sample the speech signal at a sampling rate of 8 kHz.