US5434947A
Expired / Lapsed
US
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Method for generating a spectral noise weighting filter for use in a speech coder
Assignee: BlackBerry Ltd
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Filing: 1993-02-23
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Granted: 1995-07-18
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Expires: 2013-02-23
Abstract
Abstract An Rth-order filter models the frequency response of multiple filters, to provide a filter which offers the control of multiple filters without the complexity of multiple filters. The Rth-order filter can be used as a spectral noise weighting filter or a combination of a short-term predictor filter and a spectral noise weighting filter, referred to as the spectrally noise weighted synthesis filter, depending on which embodiment is employed. In general, the method models the frequency response of L Pth-order filters by a single Rth-order filter, where the order R<L×P. Thus, this method increases the control of a speech coder filter without a corresponding increase in the complexity of the speech coder.
Inventors
- 👤 Ira A. Gerson
- 👤 Mark A. Jasiuk
- 👤 Matthew A. Hartman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:54
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/08; G10L19/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
163 words
A method of speech coding comprising the steps of: receiving speech data; providing excitation vectors; generating filter coefficients for a combined short term and spectral noise weighting filter comprising the steps of: generating a Pth-order short term filter; generating an interim spectral noise weighting filter including a first F-order filter and a second Jth-order filter, each filter dependent upon said Pth-order short term filter, and generating coefficients for a Rth-order all-pole combined short term and spectral noise weighting filter using said Pth-order short term filter and said interim spectral noise weighting filter, where R<P+F+J; filtering said received speech data; filtering said excitation vectors utilizing a long term predictor filter and said combined short term and spectral noise weighting filter, forming filtered excitation vectors; comparing said filtered excitation vectors to said filtered received speech data, forming a difference vector; calculating energy of said difference vector, forming an error signal; and choosing, using the error signal, an excitation code, I, representing the received speech data.
Claim 2
Independent Claim
163 words
A method of speech coding comprising the steps of: receiving speech data; providing excitation vectors; generating filter coefficients for a combined short term and spectral noise weighting filter comprising the steps of: generating a Pth-order short term filter; generating an interim spectral noise weighting filter including a first F-order filter and a second Jth-order filter, each filter dependent upon said Pth-order short term filter, and generating coefficients for a Rth-order all-pole combined short term and spectral noise weighting filter using said Pth-order short term filter and said interim spectral noise weighting filter, where R<P+F+J; filtering said received speech data; filtering said excitation vectors utilizing a long term predictor filter and said combined short term and spectral noise weighting filter, forming filtered excitation vectors; comparing said filtered excitation vectors to said filtered received speech data, forming a difference vector; calculating energy of said difference vector, forming an error signal; and choosing, using the error signal, an excitation code, I, representing the received speech data.
Claim 3
Independent Claim
181 words
A method of speech coding comprising the steps of: receiving speech data; providing excitation vectors in response to said step of receiving; determining short term and long term predictor coefficients for use by a long term and a Pth-order short term predictor filter; filtering said excitation vectors utilizing said long term predictor filter and said short term predictor filter, forming filtered excitation vectors; determining coefficients for a spectral noise weighting filter comprising the step of: generating an interim spectral noise weighting filter including a first F-order filter and a second Jth-order filter, dependent upon said Pth-order short term filter coefficients, and generating spectral noise weighting coefficients using a Rth-order all-pole model of said interim spectral noise weighting filter, where R<F+J; comparing said filtered excitation vectors to said received speech data, forming a difference vector; filtering said difference vector using a filter dependent upon said spectral noise weighting filter coefficients, forming a filtered difference vector; calculating energy of said filtered difference vector, forming an error signal; and choosing an excitation code, I, using the error signal, which represents the received speech data.
Claim 4
Independent Claim
181 words
A method of speech coding comprising the steps of: receiving speech data; providing excitation vectors in response to said step of receiving; determining short term and long term predictor coefficients for use by a long term and a Pth-order short term predictor filter; filtering said excitation vectors utilizing said long term predictor filter and said short term predictor filter, forming filtered excitation vectors; determining coefficients for a spectral noise weighting filter comprising the step of: generating an interim spectral noise weighting filter including a first F-order filter and a second Jth-order filter, dependent upon said Pth-order short term filter coefficients, and generating spectral noise weighting coefficients using a Rth-order all-pole model of said interim spectral noise weighting filter, where R<F+J; comparing said filtered excitation vectors to said received speech data, forming a difference vector; filtering said difference vector using a filter dependent upon said spectral noise weighting filter coefficients, forming a filtered difference vector; calculating energy of said filtered difference vector, forming an error signal; and choosing an excitation code, I, using the error signal, which represents the received speech data.
Claim 5
Dependent Claim
71 words
A method of speech coding in accordance with claim 2 wherein said step of generating coefficients for a Rth-order all-pole combined short term and spectral noise weighting filter further comprises the steps of: generating the impulse response of the interim spectral noise weighting filter; autocorrelating said impulse response, forming an autocorrelation R hh (i); and computing the coefficients of the Rth-order all-pole filter using a method of recursion and the autocorrelation.
References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1998-07-17 | 1999-01-16 | 1999-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-17 | 2003-01-16 | 2003-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-17 | 2007-01-16 | 2007-07-18 | $7700.00 | Window Closed / Lapsed |