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US5706395A
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Adaptive weiner filtering using a dynamic suppression factor
Assignee: Texas Instruments Inc
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Filing: 1995-04-19
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Granted: 1998-01-06
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Expires: 2015-04-19
Abstract
Abstract An acoustic noise suppression filter including attenuation filtering with a noise suppression factor depending upon the ratio of estimated noise energy of a frame divided by estimated signal energy.
Inventors
- 👤 Levent M. Arslan
- 👤 Alan V. McCree
- 👤 Vishu R. Viswanathan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:02
CPC Classifications
G; G10; G10L; G10L21/00; G10L21/02; G10L21/0208
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
79 words
A filter, comprising: (a) an input for receiving frames of sampled signals; (b) an attenuation filter coupled to said input, wherein said attenuation filter includes a noise suppression factor with said noise suppression factor depending on E N divided by E Y where E N is an estimate of noise energy of a frame and E Y is an estimate of signal energy of said frame; and (c) an output coupled to said attenuation filter for emitting filtered frames.
Claim 2
Dependent Claim
79 words
A filter, comprising: (a) an input for receiving frames of sampled signals; (b) an attenuation filter coupled to said input, wherein said attenuation filter includes a noise suppression factor with said noise suppression factor depending on E N divided by E Y where E N is an estimate of noise energy of a frame and E Y is an estimate of signal energy of said frame; and (c) an output coupled to said attenuation filter for emitting filtered frames.
Claim 3
Dependent Claim
19 words
The filter of claim 1, wherein: (a) said noise suppression factor is proportional to E N /E Y .
Claim 4
Dependent Claim
65 words
The filter of claim 1, wherein: (a) said attenuation filter has a transfer function H(ω) given by H(ω) 2 =P Y (ω)/(P Y (ω)+ E N /(E Y -E N !κP N (ω)) where P Y is an estimate of the signal power spectrum of said frame, P N is an estimate of the noise power spectrum of said frame, and κ is a constant.
Claim 5
Dependent Claim
16 words
The filter of claim 3, wherein: (a) κ is in the range of 6 to 7.
Claim 6
Dependent Claim
34 words
The filter of claim 3, wherein: (a) P Y is the power spectrum of a linear prediction coefficient (LPC) approximation of said frame; and (b) E Y is the energy of said LPC approximation.
Claim 7
Dependent Claim
86 words
The filter of claim 3, wherein: (a) said P N is taken equal to: (i) a first product of a first constant and a noise power spectrum estimate for a preceding frame when P Y exceeds said first product, (ii) a second product of a second constant and said noise power spectrum estimate for a preceding frame when P Y is less than said second product, and (iii) P Y otherwise; and (b) said E N is the sum over frequencies of said P N .
Claim 8
Dependent Claim
83 words
The filter of claim 1, wherein: (a) said attenuation filter has a transfer function H(ω) given by H(ω) 2 =max{C, P Y (ω)/(P Y (ω)+ E N /(E Y -E N )!κP N (ω))} where max{A,B} is the maximum of A and B for all A and B, C is a clamp, P Y is an estimate of the signal power spectrum of said frame, P Y is an estimate of the noise power spectrum of said frame, and κ is a constant.
Claim 9
Dependent Claim
86 words
The filter of claim 7, wherein: (a) said P N is taken equal to: (i) a first product of a first constant and a noise power spectrum estimate for a preceding frame when P Y exceeds said first product, (ii) a second product of a second constant and said noise power spectrum estimate for a preceding frame when P Y is less than said second product, and (iii) P Y otherwise; and (b) said E N is the sum over frequencies of said P N .
Claim 10
Dependent Claim
91 words
The filter of claim 1, wherein: (a) said attenuation filter has a transfer function H(ω) given by H(ω) 2 =W★max{C, P Y (ω)/(P Y (ω)+ E N /(E Y -E N )!κP N (ω))} where W is a window function, ★ denotes convolution, max{A,B} is the maximum of A and B for all A and B, C is a clamp, P Y is an estimate of the signal power spectrum of said frame, P N is an estimate of the noise power spectrum of said frame, and κ is a constant.
Claim 11
Independent Claim
103 words
A method of filtering a stream of sampled acoustic signals, comprising the steps of: (a) partitioning a stream of sampled acoustic signals into a sequence of frames; (b) Fourier transforming said frames to yield a sequence of transformed frames; (c) applying a generalized Wiener filter with a noise suppression factor to said transformed frames to yield a sequence of filtered transformed frames, wherein said noise suppression factor of said filter for a transformed frame depends upon estimates of the signal-to-noise ratio of said transformed frame; and (d) inverse Fourier transforming said sequence of filtered transformed frames to yield a sequence of filtered frames.
Claim 12
Independent Claim
103 words
A method of filtering a stream of sampled acoustic signals, comprising the steps of: (a) partitioning a stream of sampled acoustic signals into a sequence of frames; (b) Fourier transforming said frames to yield a sequence of transformed frames; (c) applying a generalized Wiener filter with a noise suppression factor to said transformed frames to yield a sequence of filtered transformed frames, wherein said noise suppression factor of said filter for a transformed frame depends upon estimates of the signal-to-noise ratio of said transformed frame; and (d) inverse Fourier transforming said sequence of filtered transformed frames to yield a sequence of filtered frames.
Claim 13
Dependent Claim
84 words
The method of claim 10, wherein: (a) said generalized Wiener filter has a transfer function H(ω) given by H(ω) 2 =max{C, P Y (ω)/(P Y (ω)+ E N /(E Y -E N )!κP N (ω))} where max{A,B} is the maximum of A and B for all A and B, C is a clamp, P Y is an estimate of the signal power spectrum of said frame, P N is an estimate of the noise power spectrum of said frame, and κ is a constant.
Claim 14
Dependent Claim
104 words
A speech system comprising: a. a speech acquiring module; b. a noise suppressing module couple to said acquiring module; c. an analyzing module coupled to said suppressing module; d. a transmitting/storing module coupled to said analyzing module; e. a synthesizing module coupled to said transmitting/storing module; f. a playingback module coupled to said synthesizing module; g. wherein said noise suppressing module includes an attenuating filter with a noise suppressing factor depending upon E N divide by E Y where E N is an estimate of noise energy of a frame of speech and E Y is an estimate of signal energy of said frame.
Claim 15
Dependent Claim
104 words
A speech system comprising: a. a speech acquiring module; b. a noise suppressing module couple to said acquiring module; c. an analyzing module coupled to said suppressing module; d. a transmitting/storing module coupled to said analyzing module; e. a synthesizing module coupled to said transmitting/storing module; f. a playingback module coupled to said synthesizing module; g. wherein said noise suppressing module includes an attenuating filter with a noise suppressing factor depending upon E N divide by E Y where E N is an estimate of noise energy of a frame of speech and E Y is an estimate of signal energy of said frame.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-01-05 | 2001-07-07 | 2002-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-01-05 | 2005-07-07 | 2006-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-01-05 | 2009-07-07 | 2010-01-06 | $7700.00 | Window Closed / Lapsed |