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Voice messaging system with unified pitch and voice tracking

  • US 4,696,038 A
  • Filed: 04/13/1983
  • Issued: 09/22/1987
  • Est. Priority Date: 04/13/1983
  • Status: Expired due to Term
First Claim
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1. In a voice messaging system for receiving a human speech signal and reconstituting said human speech signal at a receiver which is spatially or temporally remote, the combination comprising:

  • LPC analysis means for analyzing an analog speech signal provided as an input thereto in accordance with an LPC (Linear Predictive Coding) model, said LPC analysis means providing LPC parameters and a residual signal organized in a sequence of speech data frames and the respective residual signals corresponding thereto as an output representative of the analog speech signal;

    pitch extraction means operably associated with said LPC analysis means for determining a plurality of pitch candidates for each of the speech data frames in said sequence;

    optimization means operably associated with said LPC analysis means and said pitch extraction means for performing dynamic programming with respect both to said plurality of pitch candidates for each speech data frame and also to a voiced/unvoiced decision for each speech data frame to determine both an optimal pitch and an optimal voicing decision for each speech data frame in the context of sequence of speech data frames, said optimization means defining a transition error between each pitch candidate of the current frame and each pitch candidate of the preceding frame, and defining a cumulative error for each pitch candidate in the current frame which is equal to the transition error between said pitch candidate of said current frame plus the cumulative error of an optimally identified pitch cnadidate in the preceding frame, said optimally identified pitch candidate in the preceding frame being chosen from among the pitch candidates for said preceding frame such that the cumulative error of said corresponding pitch candidate in said current frame is at a minimum; and

    means operably associated with said LPC analysis means, said pitch extraction means and said optimization means for encoding said LPC parameters and said optimal pitch and optimal voicing decision for each speech data frame.

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