Speech message code modifying arrangement
First Claim
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1. Apparatus for coding a speech pattern comprising:
- means for partitioning said speech pattern into successive time frame portions;
means responsive to each successive time frame portion of the speech pattern for generating speech parameter signals comprising a set of linear predictive parameter type spectral representative signals and an excitation signal comprising a sequence of excitation pulses each of amplitude beta and location m within said time frame;
means responsive to the frame speech parameter signals for identifying successive intervals of said speech pattern as voiced or other than voiced, each voiced interval being a plurality of time frame portions coextensive with a pitch period of said speech pattern and each other than voiced interval comprising a time frame portion of said speech pattern; and
means for modifying the excitation signals of each successive identified voiced interval to compress the speech pattern excitation signals of said speech pattern;
said modifying means including;
means responsive to each other than voiced interval for forming an excitation signal comprising the sequence of excitation pulses of the time frame portion of the other than voiced interval;
means responsive to the occurrence of a succession of identified voiced intervals for forming an excitation signal comprising the sequence of excitation pulses of the pitch period of a selected one of said succession of identified voiced intervals; and
means for forming an excitation signal for each of the remaining voiced intervals of said succession of identified voiced intervals comprising a coded signal repeating the sequence of excitation signals of the pitch period of said selected identified voiced interval.
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Abstract
Natural quality and bit-rate for LPC speech synthesis is improved by encoding the LPC residual signal in a prescribed multipulse format formed for each LPC frame. Voiced, unvoiced, and mixed (hiss plus periodic) excitation is inherent. The speaking-rate is changed by adding, deleting, or repeating pitch-periods, and the pitch (intonation) is changed by adding or deleting zeros in the multipulse excitation signal.
195 Citations
22 Claims
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1. Apparatus for coding a speech pattern comprising:
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means for partitioning said speech pattern into successive time frame portions; means responsive to each successive time frame portion of the speech pattern for generating speech parameter signals comprising a set of linear predictive parameter type spectral representative signals and an excitation signal comprising a sequence of excitation pulses each of amplitude beta and location m within said time frame; means responsive to the frame speech parameter signals for identifying successive intervals of said speech pattern as voiced or other than voiced, each voiced interval being a plurality of time frame portions coextensive with a pitch period of said speech pattern and each other than voiced interval comprising a time frame portion of said speech pattern; and means for modifying the excitation signals of each successive identified voiced interval to compress the speech pattern excitation signals of said speech pattern; said modifying means including; means responsive to each other than voiced interval for forming an excitation signal comprising the sequence of excitation pulses of the time frame portion of the other than voiced interval; means responsive to the occurrence of a succession of identified voiced intervals for forming an excitation signal comprising the sequence of excitation pulses of the pitch period of a selected one of said succession of identified voiced intervals; and means for forming an excitation signal for each of the remaining voiced intervals of said succession of identified voiced intervals comprising a coded signal repeating the sequence of excitation signals of the pitch period of said selected identified voiced interval. - View Dependent Claims (2, 3, 4, 5)
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6. A method for altering a speech message comprising the steps of:
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generating a time frame sequence of speech parameter signals representative of a speech message, each time frame speech parameter signal including a set of spectral representative signals and an excitation signal comprising a sequence of excitation pulses of varying amplitudes and varying locations within the time frame; generating a sequence of speech message time frame editing signals; identifying a succession of prescribed type excitation signal intervals, said succession being identified in response to groups of the time frame speech parameter signals having various pitch periods; modifying the excitation and spectral representative signals of the frames of the prescribed type excitation signal intervals in response to said speech message editing signals; and forming an edited speech message responsive to the modified excitation and spectral representative signals. - View Dependent Claims (7, 8)
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9. Apparatus for altering a speech message comprising:
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means responsive to the speech message for generating a time frame sequence of speech parameter signals representative of a speech message, each time frame speech parameter signal including a set of spectral representative signals and an excitation signal of the multi-pulse type; means responsive to the time frame speech parameter signals for identifying a succession of pitch period signal intervals; means for generating a sequence of speech message time frame editing signals responsive in part to the identifying means; means responsive to said speech message editing signals for increasing the repetitiveness of at least some of the excitation and spectral representative signals of the frames of the pitch period signal intervals; and means responsive to the modified excitation and spectral representative signals for forming an edited speech message. - View Dependent Claims (10, 11)
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12. A method for altering a speech message coded as a sequence of time frame spectral representative signals and multi-pulse excitation signals comprising the steps of:
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generating a predetermined speech message editing signal; identifying prescribed type intervals in the excitation signal sequence of the coded speech message; and increasing the repetitiveness of the multi-pulse excitation signals of selected prescribed type intervals responsive to said speech message editing signal. - View Dependent Claims (13, 14, 15, 16, 17)
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18. Apparatus for altering a speech message coded as a time frame sequence of spectral representative and multi-pulse excitation signals comprising:
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means for generating a predetermined speech message editing signal; means responsive to said speech message spectral representative and excitation signals for identifying prescribed type sequential intervals of the at-least-partially voiced type in the excitation signal sequence of the coded speech message; and means responsive to said speech message editing signal for increasing the repetitiveness of the excitation signals of the identified prescribed type intervals by repeating a selected group of multi-pulse excitation signals representative of one such interval in the other sequential intervals to reduce the effective bit rate of the resulting coded speech message. - View Dependent Claims (19, 20, 21, 22)
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Specification