EP0285276A2
Expired / Lapsed
EP
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Coding of acoustic waveforms
Assignee: Massachusetts Institute of Technology
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Filing: 1988-03-10
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Granted: —
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Expires: 2008-03-10
Abstract
Abstract Encoding techniques and devices based on a sinusoidal speech representation model are disclosed. In one aspect of the invention, a pitch-adaptive channel encoding technique for amplitude coding is disclosed in which the channel spacing is varied in accordance with the pitch of the speaker's voice. In another aspect of the invention, a phase synthesis technique is disclosed which locks rapidly-varying phases into synchrony with the phase of the fundamental. Phase coding techniques which introduce a voice-dependent random phase and a pitch-adaptive quadratic phase dispersion are also disclosed.
Inventors
- 👤 Robert J. Mcaulay
- 👤 Thomas F. Quatieri, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 01:11
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/02
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
131 words
A method of coding speech for digital transmission, the method comprising: sampling the speech to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing each frame of samples to extract a set of frequency components having individual amplitudes and phases; tracking said components from one frame to the next frame; interpolating the values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic speech waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation; and coding the frequency components for digital transmission, such that excitation contributions to the phases of the frequency components are locked into synchrony.
Claim 2
Independent Claim
131 words
A method of coding speech for digital transmission, the method comprising: sampling the speech to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing each frame of samples to extract a set of frequency components having individual amplitudes and phases; tracking said components from one frame to the next frame; interpolating the values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic speech waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation; and coding the frequency components for digital transmission, such that excitation contributions to the phases of the frequency components are locked into synchrony.
Claim 3
Dependent Claim
37 words
A method as claimed in claim 1, characterised in that the step of coding the frequency components further includes determining a pitch onset time to establish a time at which the frequency components come into phase synchrony.
Claim 4
Dependent Claim
53 words
A method as claimed in claim 1, characterised in that the step of analyzing each frame to extract frequency components further includes predicting the phases of the frequency components by homomorphic transformation and pitch onset time analysis, and the step of coding the frequency components includes coding only the phase residuals for transmission.
Claim 5
Dependent Claim
41 words
A method as claimed in claim 1, characterised in that the step of coding the frequency components further includes applying a pitch-dependent quadratic phase dispersion to the frequency components to eliminate the need to code phase values for the frequency components.
Claim 6
Dependent Claim
41 words
A method as claimed in claim 1, characterised in that the step of coding the frequency components further includes generating a voicing dependent random phase for said frequency components to eliminate the need to code phase values for the frequency components.
Claim 7
Dependent Claim
52 words
A method as claimed in claim 1, characterised in that the step of analyzing each frame to extract frequency components further includes determining a phase of a fundamental frequency by integrating an instantaneous pitch frequency, and defining the phases of the frequency components as multiples of the phase of the fundamental frequency.
Claim 8
Independent Claim
136 words
A method of coding speech for digital transmission, the method comprising: sampling the speech to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing each frame of samples to extract a set of frequency components having individual amplitudes and phases; tracking said components from one frame to the next frame; interpolating the values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic speech waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation; and coding the frequency components for digital transmission, such that the frequency components are limited to a set of amplitude channels defined by a plurality of harmonic frequencies.
Claim 9
Independent Claim
136 words
A method of coding speech for digital transmission, the method comprising: sampling the speech to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing each frame of samples to extract a set of frequency components having individual amplitudes and phases; tracking said components from one frame to the next frame; interpolating the values of the components from the one frame to the next frame to obtain a parametric representation of the waveform whereby a synthetic speech waveform can be constructed by generating a set of sine waves corresponding to the interpolated values of the parametric representation; and coding the frequency components for digital transmission, such that the frequency components are limited to a set of amplitude channels defined by a plurality of harmonic frequencies.
Claim 10
Dependent Claim
33 words
A method as claimed in claim 7, characterised in that the step of coding the frequency components further includes varying the number of amplitude channels based on a pitch measurement of the speech.
Claim 11
Dependent Claim
42 words
A method as claimed in claim 7, characterised in that the step of coding the frequency components further includes defining a first set of linearly-spaced frequency channels in a baseband, and a second set of logarithmatically-spaced channels in a higher frequency region.
Claim 12
Dependent Claim
43 words
A method as claimed in claim 9, characterised in that the step of defining said linear and logarithmatically-spaced channels further includes defining a transition frequency from said linearly-spaced frequency channels to said logarithmatically-spaced frequency channels based on a pitch measurement of the speech.
Claim 13
Dependent Claim
92 words
A speech coding device comprising: sampling means for sampling a speech waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples by Fourier analysis to extract a set of frequency components having individual amplitude and phase values; tracking means for tracking the components from one frame to a next frame; and coding means for coding the components such that excitation contributions of the phases of the frequency components are locked into synchrony.
Claim 14
Dependent Claim
92 words
A speech coding device comprising: sampling means for sampling a speech waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples by Fourier analysis to extract a set of frequency components having individual amplitude and phase values; tracking means for tracking the components from one frame to a next frame; and coding means for coding the components such that excitation contributions of the phases of the frequency components are locked into synchrony.
Claim 15
Dependent Claim
31 words
A device as claimed in claim 11, characterised in that the analyzing means further includes a pitch onset estimator for establishing a time at which the frequency components come into phase.
Claim 16
Dependent Claim
41 words
A device as claimed in claim 11, characterised in that the analyzing means further includes a homomorphic phase estimator for estimating the phases of the frequency components and the coding means further includes means for coding only phase residuals for transmission.
Claim 17
Dependent Claim
32 words
A device as claimed in claim 11, characterised in that the coding means further includes a quadratic phase dispersion computer which eliminates the need to code phase values for the frequency components.
Claim 18
Dependent Claim
30 words
A device as claimed in claim 11, characterised in that the coding means further includes a random phase generator for generating a voicing dependent random phase for the frequency components.
Claim 19
Dependent Claim
49 words
A device as claimed in claim 11, characterised in that the analyzing means further includes means for determining the phase of a fundamental frequency by integrating an instantaneous pitch frequency and means for defining the phases of the frequency components as multiples of the phase of the fundamental frequency.
Claim 20
Dependent Claim
96 words
A speech coding device comprising: sampling means for sampling a speech waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples by Fourier analysis to extract a set of frequency components having individual amplitude and phase values, tracking means for tracking the components from one frame to a next frame; and coding means for coding the components such that the frequency components are limited to a set of channels defined by a plurality of harmonic frequencies.
Claim 21
Dependent Claim
96 words
A speech coding device comprising: sampling means for sampling a speech waveform to obtain a series of discrete samples and constructing therefrom a series of frames, each frame spanning a plurality of samples; analyzing means for analyzing each frame of samples by Fourier analysis to extract a set of frequency components having individual amplitude and phase values, tracking means for tracking the components from one frame to a next frame; and coding means for coding the components such that the frequency components are limited to a set of channels defined by a plurality of harmonic frequencies.
Claim 22
Dependent Claim
30 words
A device as claimed in claim 17, characterised in that the coding means further includes means for varying the number of channels based on a pitch measurement of the speech.
Claim 23
Dependent Claim
37 words
A device as claimed in claim 17, characterised in that the coding means further includes a first set of linearly-spaced frequency channels in a baseband, and a second set of logarithmatically-spaced channels in a higher frequency region.
Claim 24
Dependent Claim
29 words
A device as claimed in claim 19, characterised in that the coding means further includes means for defining a transition frequency from said linearly-spaced channels to said logarithmatically-spaced channels.
References Cited (Backward Citations)
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