Speech-recognition method and apparatus for recognizing phonemes in a voice signal
First Claim
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1. A method for recognizing particular phonemes in a voice signal having silence-phoneme and phoneme-phoneme transitions, said method comprising the steps of:
- providing an electrical signal representing said voice signal;
producing a first acoustic parameter signal from said electrical signal, said first acoustic parameter signal containing phonemic information of said voice signal;
generating a transition signal from the phonemic information in said first acoustic parameter signal indicating the location in said voice signal of a transition;
storing said first acoustic parameter signal; and
producing a second acoustic parameter signal from said stored first acoustic parameter signal using said transition signal, said second acoustic parameter signal containing phonemic information of said voice signal at said transition, whereby said second acoustic parameter signal can be compared with known phonemic information to recognize the phonemic information in said voice signal.
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Abstract
Phoneme recognition uses the silence-phoneme and phoneme-phoneme transition spectral information rather than the phoneme information itself. The transition detector features first and second differences in level for each frequency band.
56 Citations
28 Claims
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1. A method for recognizing particular phonemes in a voice signal having silence-phoneme and phoneme-phoneme transitions, said method comprising the steps of:
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providing an electrical signal representing said voice signal; producing a first acoustic parameter signal from said electrical signal, said first acoustic parameter signal containing phonemic information of said voice signal; generating a transition signal from the phonemic information in said first acoustic parameter signal indicating the location in said voice signal of a transition; storing said first acoustic parameter signal; and producing a second acoustic parameter signal from said stored first acoustic parameter signal using said transition signal, said second acoustic parameter signal containing phonemic information of said voice signal at said transition, whereby said second acoustic parameter signal can be compared with known phonemic information to recognize the phonemic information in said voice signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for recognizing particular phonemes in a voice signal having silence-phoneme and phoneme-phoneme transition, said apparatus comprising:
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means for providing an electrical signal representing said voice signal; first parameter producing means for producing a first acoustic parameter signal from said electrical signal, said first acoustic parameter signal containing phonemic information of said voice signal; generating means for generating a transition signal from the phonemic information in said first acoustic parameter signal, said transition signal indicating the location in said voice signal of a transition; storage means for storing said first acoustic parameter signal; and second parameter producing means for producing a second acoustic parameter signal from said stored first acoustic parameter signal using said transition signal, said second acoustic parameter signal containing phonemic information of said voice signal at said transition, whereby said second acoustic parameter signal can be compared with known phonemic information to recognize the phonemic information in said voice signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for generating a transition signal for indicating the location of a transition in a voice signal having silence-phoneme and phoneme-phoneme transitions, the method comprising the steps of:
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providing an acoustic parameter signal containing phonemic information of the voice signal; separating a plurality of time frames of said acoustic parameter signal into a plurality of frequency band signals, each said frequency band signal representing a power level of said acoustic parameter signal in a particular frequency band and time frame; calculating from said plurality of frequency band signals an average power level at each said time frame; calculating for all said time frames a plurality of first difference levels between said average power level at each said time frame and said plurality of power levels at the same frame; calculating for all said frequency bands a plurality of second difference levels between; (1) the lowest of said first difference levels in each said frequency band for said plurality of time frames, and (2) each said first difference level in the same frequency band for said plurality of time frames; and calculating the sum of all of said second difference levels, whereby said sum comprises said transition signal which can be evaluated to detect transitions in said voice signal. - View Dependent Claims (20, 21, 22, 23)
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24. An apparatus for generating a transition signal that can be evaluated to indicate the location in a voice signal of silence-phoneme and phoneme-phoneme transitions, the apparatus comprising:
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means for separating a plurality of time frames of an acoustic parameter signal containing phonemic information of the voice signal into a plurality of frequency band signals, each said frequency band signal representing a power level of said acoustic parameter signal in a particular frequency band and time frame; averaging means for calculating from said plurality of frequency band signals an average power level at each said time frame; difference circuit means for calculating for all said time frames a plurality of first difference levels between said average power level at each said time frame and said plurality of power levels at the same time frame; memory means for storing a plurality of said first difference levels for a plurality of time frames; operating circuit means for determining from said stored first difference levels a plurality of minimum first difference levels, each said frequency band having a minimum first difference level for said plurality of time frames; and summing means for calculating the sum of a plurality of second difference levels, each comprising the difference between; (1) said minimum first difference level in each said frequency band, and (2) each said first difference level in the same frequency band for said plurality of time frames, whereby said sum comprises said transition signal which can be evaluated to detect transitions in said voice signal. - View Dependent Claims (25, 26, 27, 28)
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Specification