Voice source for synthetic speech system

Claim 2

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses, each glottal pulse having a different desired frequency and being a selected portion of a speech waveform, said speech waveform being created by measuring sound pressures of a human spoken sound at successive sample points in time and inverse-filtering the measurements to remove vocal tract components; storage means for storing said plurality of glottal pulses; and means for utilizing said plurality of glottal pulses to generate a synthetic voice signal.

Claim 3

The improvement in said synthetic voice generating system of claim 1 wherein said storage means comprises: a memory look-up table containing a plurality of sample points for each one of said glottal pulses.

Claim 4

The improvement in said synthetic voice generating system of claim 2 wherein said means for utilizing comprises: pitch control means for modifying said glottal pulses to vary the pitch of the glottal pulses, said glottal pulses being modified by uniformly interpolating between sample points of said glottal pulses to produce a modified glottal pulse having more or fewer sample points.

Claim 5

The improvement in said synthetic voice generating system of claim 3 wherein said means for utilizing further comprises: amplitude control means for increasing or decreasing the amplitude of the time-domain glottal pulses modified by said pitch control means.

Claim 6

The improvement in said synthetic voice generating system of claim 1 wherein said storage means comprises: a memory means for storing a plurality of glottal pulses in time-domain form, each glottal pulse having therefor a different pitch period.

Claim 7

The improvements in said synthetic voice generating system of claim 5 wherein said means for utilizing comprises: pitch control means for selecting a particular sequence of glottal pulses and concatenating them together.

Claim 8

The improvements in said synthetic voice generating system of claim 6 wherein said means for utilizing further comprises: amplitude control means for increasing or decreasing the amplitude of the time-domain glottal pulses concatenated by said pitch control means.

Claim 9

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses stored in a storage means, each glottal pulse having a desired frequency and being a selected portion of a speech waveform, said speech waveform being created by measuring sound pressures of a human spoken sound at successive sample points in time and inverse-filtering the measurements to remove vocal tract components; a voice source means for generating a signal representing the sound produced by a human larynx by combining a plurality of said stored glottal pulses; and a vocal tract simulating means for modifying the signals from said voice source means to simulate the effect of a human vocal tract on said voice source signals.

Claim 10

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses stored in a storage means, each glottal pulse having a desired frequency and being a selected portion of a speech waveform, said speech waveform being created by measuring sound pressures of a human spoken sound at successive sample points in time and inverse-filtering the measurements to remove vocal tract components; a voice source means for generating a signal representing the sound produced by a human larynx by combining a plurality of said stored glottal pulses; and a vocal tract simulating means for modifying the signals from said voice source means to simulate the effect of a human vocal tract on said voice source signals.

Claim 11

The improvement of claim 8 wherein said vocal tract simulating means comprises: a cascade of second order digital filters.

Claim 12

The improvement of claim 9 wherein besides said voice source signal, said digital filters receive signals from a noise source means which generates signals representing air turbulence in the voice tract.

Claim 13

The improvement of claim 10 wherein said noise source means comprises: an aspiration source means for generating signals representing air turbulence at the vocal cords; and a frication source means using frications from real speech for generating signals representing air turbulence in vocal cavities of the pharynx, mouth and nose.

Claim 14

The improvements of claim 8 wherein the voice source means comprises: storage means for storing a plurality of different time domain glottal pulses derived from a human source; and means for utilizing the glottal pulses in said storage means to generate a synthetic voice signal.

Claim 15

The improvement of claim 12 wherein said storage means comprises: a plurality of memory look-up tables, each table containing a plurality of sample points representing a small group of glottal pulses, in code form.

Claim 16

The improvement of claim 13 wherein said utilizing means comprises: means for cross-fading between a departing memory look-up table and in entering memory look-up table according to the relation: S.P.=A X.sub.n +B Y.sub.n wherein A and B are fractions that total 1, X n is a sample point near the end of the departing look-up table, Y n is a sample point near the beginning of the entry look-up table, and S.P. is the resulting sample point.

Claim 17

The improvement of claim 12 wherein said storage means comprises: a memory look-up table containing a plurality of sample points for each one of said time domain glottal pulses.

Claim 18

The improvement of claim 15 wherein said utilizing means comprises: pitch control means for modifying said glottal pulses by varying the pitch period of each glottal pulse by uniformly interpolating between the sample points of a selected glottal pulse to produce a modified glottal pulse having more sample points.

Claim 19

The improvement of claim 16 wherein said utilizing means further comprises: amplitude control means for increasing or decreasing the amplitude of the time-domain glottal pulses modified by said pitch control means.

Claim 20

The improvement of claim 17 wherein said vocal tract simulating means comprises a cascade of second order digital filters.

Claim 21

The improvement of claim 18 wherein besides said voice source signal, said digital filters receive signals from a noise source means which generates signals representing air turbulence in the voice tract.

Claim 22

The improvement of claim 19 wherein said one noise source means comprises: an aspiration source means for generating signals representing air turbulence at the vocal cords; and a frication source means using frications from real speech for generating signals representing air turbulence in vocal cavities of the pharynx, mouth and nose.

Claim 23

The improvement of claim 12 wherein said storage means comprises: a memory means for storing a plurality of glottal pulses in time-domain form, each glottal pulse having a different pitch period.

Claim 24

The improvement of claim 21 wherein said utilizing means comprises: pitch control means for selecting a particular sequence of glottal pulses and concatenating them together.

Claim 25

The improvement of claim 22 wherein said utilizing means further comprises: means for cross-fading between an ending glottal pulse and a beginning glottal pulse to be concatenated together, according to the relation: S.P.=A X.sub.n +B Y.sub.n wherein A and B are fractions that always total 1, X n is a point on the ending glottal pulse to be joined to the beginning glottal pulse, Y n is a point on the beginning glottal pulse, and S.P. is the resulting sample point which is a combination of the ending glottal pulse and the beginning glottal pulse.

Claim 26

The improvement of claim 22 wherein said means for utilizing further comprises: amplitude control means for increasing or decreasing the amplitude of the glottal pulses concatenated by said pitch control means.

Claim 27

The improvement of claim 24 wherein said vocal tract simulating means comprises a cascade of second order digital filters.

Claim 28

The improvement of claim 25 wherein besides said voice source signal, said digital filters receive signals from a noise source means which generates signals representing air turbulence in the voice tract.

Claim 29

The improvement of claim 26 wherein said one noise source means comprises: an aspiration source means for generating signals representing air turbulence at the vocal cords; and a frication source means using frications from real speech for generating signals representing air turbulence in vocal cavities of the pharynx, mouth and nose.

Claim 30

The improvement of claim 12 wherein said storage means comprises: a memory means for storing a plurality of glottal pulses in code form.

Claim 31

The improvement of claim 28 wherein said utilizing means comprises: pitch control means for selecting a particular sequence of glottal pulses and concatenating them together.

Claim 32

The improvement of claim 29 further comprising an address look-up table for said memory means, said address look-up table providing addresses to certain glottal pulses stored in said memory means in response to the parameters of period and amplitude.

Claim 33

The method of claim 30, further comprising, after said measuring step, the step of filtering the measured human speech sounds by an antialias filter.

Claim 34

The improvement of claim 29 wherein said memory means stores the addresses of a plurality of other possible neighbor glottal pulses along with each glottal pulse stored, whereby only the neighbor glottal pulses are selected for concatenating with said stored glottal pulse.

Claim 35

The improvement of claim 32 wherein said utilizing means further comprises: means for cross-fading between a selected ending glottal pulse and a selected beginning glottal pulse to be concatenated together, according to the relation: S.P.=A X.sub.n +B Y.sub.n wherein A and B are functions that always total 1, X n is a point on the ending glottal pulse, Y n is a point on the beginning glottal pulse, and S.P. is the resulting sample point which is a combination of the ending and beginning glottal pulses.

Claim 36

The improvement of claim 29 wherein said memory means stores the address of one other glottal pulse along with each glottal pulse stored, effectively providing a list of glottal pulses, whereby the stored glottal pulses and the list of glottal pulses are examined to determine which one best meets the requirement.

Claim 37

The improvement of claim 34 wherein said utilizing means further comprises: means for cross-fading between a selected ending glottal pulse and a selected beginning glottal pulse to be concatenated together, according to the relation: S.P.=A X.sub.n +B Y.sub.n wherein A and B are fractions that always total 1, X n is a point on the ending glottal pulse, Y n is a point on the beginning glottal pulse, and S.P. is the resulting sample point which is a combination of the starting and beginning glottal pulses.

Claim 38

The improvement of claim 29 further comprising an address look-up table for said memory means, said address look-up table providing addresses to certain glottal pulses stored in said memory means in response to the parameters of period, amplitude, and phoneme.

Claim 39

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses said glottal pulses having different desired frequencies and being a selected portion of an inverse-filtered human speech waveform; storage means for storing said glottal pulses; means for retrieving said glottal pulses from said storage means; and means for applying said glottal pulses to a synthesis filter to generate a synthetic voice signal.

Claim 40

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses said glottal pulses having different desired frequencies and being a selected portion of an inverse-filtered human speech waveform; storage means for storing said glottal pulses; means for retrieving said glottal pulses from said storage means; and means for applying said glottal pulses to a synthesis filter to generate a synthetic voice signal.

Claim 41

The improved synthetic noise generating system of claim 37 wherein said speech waveform is created by measuring the sound pressure of a human spoken sound at successive points in time.

Claim 42

The improved synthetic voice generating system of claim 38 wherein said vocal tract components are removed by inverse filtering.

Claim 43

In a synthetic voice generating system, the improvement comprising: a plurality of stored glottal pulses, each stored glottal pulse having a desired frequency and being a selected portion of a speech waveform, said speech waveform created by measuring sound pressures of a human spoken sound at successive sample points in time and inverse-filtering the measurements to remove vocal tract components; a noise source means for generating a signal representing the sound produced by a human larynx by combining a plurality of said stored glottal pulses; and a vocal tract simulating means for modifying the signals from said noise source means to simulate the effect of a human vocal tract on said noise source signals.

Claim 44

In a synthetic voice generating system, the improvement comprising: a plurality of stored glottal pulses, each stored glottal pulse having a desired frequency and being a selected portion of a speech waveform, said speech waveform created by measuring sound pressures of a human spoken sound at successive sample points in time and inverse-filtering the measurements to remove vocal tract components; a noise source means for generating a signal representing the sound produced by a human larynx by combining a plurality of said stored glottal pulses; and a vocal tract simulating means for modifying the signals from said noise source means to simulate the effect of a human vocal tract on said noise source signals.

Claim 45

The improved synthetic noise generating system of claim 40 wherein said speech waveform is created by measuring the sound pressure of a human spoken sound at successive points in time.

Claim 46

The improved synthetic voice generating system of claim 40 wherein said vocal tract components are removed by inverse filtering.

Claim 47

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses in a storage means, said pulses comprising portions of glottal waveforms generated by inverse filtering time-domain representations of human speech with a plurality of second-order, finite-impulse-response filters with zeros chosen to cancel human vocal tract resonance components therefrom, each of said plurality of glottal pulses having a desired frequency and including frequency domain and time domain characteristics of human speech; pitch control means for receiving said plurality of glottal pulses and generating pitch-modified glottal pulses; amplitude control means for receiving said pitch-modified glottal pulses and increasing or decreasing an amplitude of said pitch-modified glottal pulses to generate amplitude-modified glottal pulses; and vocal tract simulating means for modifying said amplitude-modified glottal pulses received from said amplitude control means to simulate human vocal tract resonances on said amplitude-modified glottal pulses.

Claim 48

In a synthetic voice generating system, the improvement therein comprising: a plurality of glottal pulses in a storage means, said pulses comprising portions of glottal waveforms generated by inverse filtering time-domain representations of human speech with a plurality of second-order, finite-impulse-response filters with zeros chosen to cancel human vocal tract resonance components therefrom, each of said plurality of glottal pulses having a desired frequency and including frequency domain and time domain characteristics of human speech; pitch control means for receiving said plurality of glottal pulses and generating pitch-modified glottal pulses; amplitude control means for receiving said pitch-modified glottal pulses and increasing or decreasing an amplitude of said pitch-modified glottal pulses to generate amplitude-modified glottal pulses; and vocal tract simulating means for modifying said amplitude-modified glottal pulses received from said amplitude control means to simulate human vocal tract resonances on said amplitude-modified glottal pulses.

Claim 51

The method of generating speech according to claim 44, wherein the step of storing the glottal pulses includes a step of storing at least one glottal pulse for each desired frequency.

Claim 54

The method of generating synthetic speech according to claim 46, wherein the step of concatenating the two glottal pulses includes the step of segmenting the two glottal pulses at zero crossings and joining the two pulses at the segmentation.