US5581656A
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Methods for generating the voiced portion of speech signals
Assignee: Digital Voice Systems Inc
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Filing: 1993-04-06
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Granted: 1996-12-03
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Expires: 2013-04-06
Abstract
Abstract The pitch estimation method is improved. Sub-integer resolution pitch values are estimated in making the initial pitch estimate; the sub-integer pitch values are preferably estimated by interpolating intermediate variables between integer values. Pitch regions are used to reduce the amount of computation required in making the initial pitch estimate. Pitch-dependent resolution is used in making the initial pitch estimate, with higher resolution being used for smaller values of pitch. The accuracy of the voiced/unvoiced decision is improved by making the decision dependent on the energy of the current segment relative to the energy of recent prior segments; if the relative energy is low, the current segment favors an unvoiced decision; if high, it favors a voiced decision. Voiced harmonics are generated using a hybrid approach; some voiced harmonics are generated in the time domain, whereas the remaining harmonics are generated in the frequency domain; this preserves much of the computational savings of the frequency domain approach, while at the same time improving speech quality. Voiced harmonics generated in the frequency domain are generated with higher frequency accuracy; the harmonics are frequency scaled, transformed into the time domain with a Discrete Fourier Transform, interpolated and then time scaled.
Inventors
- 👤 John C. Hardwick
- 👤 Jae S. Lim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:36
CPC Classifications
G; G10; G10L; G10L13/00; G10L25/00; G10L25/90; G10L19/00; G10L19/04; G10L19/08; G10L19/087; G10L25/93
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
97 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics that consist of at least two groups of said harmonics; generating said first group of harmonics from said signal using a time domain synthesis method; generating a second signal from said information on said second group of harmonics using a frequency domain synthesis method; and combining said generated first group of harmonics and said generated second signal to generate said portion or all of a speech signal.
Claim 2
Independent Claim
97 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics that consist of at least two groups of said harmonics; generating said first group of harmonics from said signal using a time domain synthesis method; generating a second signal from said information on said second group of harmonics using a frequency domain synthesis method; and combining said generated first group of harmonics and said generated second signal to generate said portion or all of a speech signal.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said first group comprises low-frequency harmonics.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein said second group comprises high-frequency harmonics.
Claim 5
Dependent Claim
19 words
The method of claim 1 wherein said time domain synthesis is performed by generating a low-order piecewise phase polynomial.
Claim 6
Dependent Claim
72 words
The method of claim 1 wherein said frequency domain synthesis is performed using the method comprising the steps of: linearly frequency scaling said information on said harmonics according to the mapping ##EQU24## where L is some small integer, to generate frequency-scaled harmonics; performing an L-point Inverse Discrete Fourier Transform (DFT) to simultaneously transform said frequency scaled harmonics into the time domain; and performing interpolation and time scaling to generate said second signal.
Claim 7
Dependent Claim
22 words
The method of claim 1 or 5 wherein said synthesized speech is the voiced portion of a multi-band excitation (MBE) speech coder.
Claim 8
Dependent Claim
22 words
The method of claim 1 or 2 wherein said information on said plurality of harmonics represents parameters of a Sinusoidal Transform Coder.
Claim 9
Independent Claim
91 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics that consist of at least two groups of said harmonics; generating a first signal from said first group of harmonics using a time domain synthesis method; generating a second signal from said second group of harmonics using a frequency domain synthesis method; and combining said first signal and said second signal to generate said portion or all of a speech signal.
Claim 10
Independent Claim
91 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics that consist of at least two groups of said harmonics; generating a first signal from said first group of harmonics using a time domain synthesis method; generating a second signal from said second group of harmonics using a frequency domain synthesis method; and combining said first signal and said second signal to generate said portion or all of a speech signal.
Claim 11
Dependent Claim
12 words
The method of claim 8 wherein said first group comprises low-frequency harmonics.
Claim 12
Dependent Claim
12 words
The method of claim 8 wherein said second group comprises high-frequency harmonics.
Claim 13
Dependent Claim
19 words
The method of claim 8 wherein said time domain synthesis is performed by generating a low-order piecewise phase polynomial.
Claim 14
Dependent Claim
72 words
The method of claim 8 wherein said frequency domain synthesis is performed using the method comprising the steps of: linearly frequency scaling said information on said harmonics according to the mapping ##EQU25## where L is some small integer, to generate frequency-scaled harmonics; performing an L-point Inverse Discrete Fourier Transform (DFT) to simultaneously transform said frequency scaled harmonics into the time domain; and performing interpolation and time scaling to generate said second signal.
Claim 15
Dependent Claim
22 words
The method of claim 8 or 12 wherein said synthesized speech is the voiced portion of a multi-band excitation (MBE) speech coder.
Claim 16
Dependent Claim
22 words
The method of claim 8 or 12 wherein said information on said plurality of harmonics represents parameters of a Sinusoidal Transform Coder.
Claim 17
Independent Claim
101 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics; linearly frequency scaling said information on said harmonics according to the mapping ##EQU26## where L is some small integer, to generate frequency-scaled harmonics; performing an L-point Inverse Discrete Fourier Transform (DFT) to simultaneously transform said frequency scaled harmonics into the time domain; and performing interpolation and time scaling on said frequency scaled harmonics that have been transformed into the time domain to generate said portion or all of a speech signal.
Claim 18
Independent Claim
101 words
A method for synthesizing a portion or all of a speech signal from harmonics, the method comprising the steps of: processing a signal containing information on a plurality of harmonics; linearly frequency scaling said information on said harmonics according to the mapping ##EQU26## where L is some small integer, to generate frequency-scaled harmonics; performing an L-point Inverse Discrete Fourier Transform (DFT) to simultaneously transform said frequency scaled harmonics into the time domain; and performing interpolation and time scaling on said frequency scaled harmonics that have been transformed into the time domain to generate said portion or all of a speech signal.
Claim 19
Dependent Claim
20 words
The method of claim 15 wherein said synthesized speech is the voiced portion of a multi-band excitation (MBE) speech coder.
Claim 20
Dependent Claim
20 words
The method of claim 15 wherein said information on said plurality of harmonics represents parameters of a Sinusoidal Transform Coder.
Claim 21
Dependent Claim
18 words
The method of claim 5, 12 or 15 wherein said DFT is computed with a Fast Fourier Transform.
Claim 22
Dependent Claim
16 words
The method of claim 5, 12 or 15 wherein said interpolation is performed with linear interpolation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-12-03 | 2000-06-03 | 2000-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-12-03 | 2004-06-03 | 2004-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-12-03 | 2008-06-03 | 2008-12-03 | $7700.00 | Window Closed / Lapsed |