US5943429A
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Spectral subtraction noise suppression method
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1996-01-12
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Granted: 1999-08-24
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Expires: 2016-01-12
Abstract
Abstract PCT No. PCT/SE96/00024 Sec. 371 Date Jul. 28, 1997 Sec. 102(e) Date Jul. 28, 1997 PCT Filed Jan. 12, 1996 PCT Pub. No. WO96/24128 PCT Pub. Date Aug. 8, 1996A spectral subtraction noise suppression method in a frame based digital communication system is described. Each frame includes a predetermined number N of audio samples, thereby giving each frame N degrees of freedom. The method is performed by a spectral subtraction function +E,cir H+EE (w) which is based on an estimate of the power spectral density of background noise of non-speech frames and an estimate +E,cir PHI +EE x(w) of the power spectral density of speech frames. Each speech frame is approximated by a parametric model that reduces the number of degrees of freedom to less than N. The estimate +E,cir PHI +EE x(w) of the power spectral density of each speech frame is estimated from the approximative parametric model.
Inventors
- 👤 Peter Handel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:06
CPC Classifications
G; G10; G10L; G10L21/00; G10L21/02; G10L21/0208; G10L21/0216; G10L2021/02168; G10L21/0264
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
145 words
A spectral subtraction noise suppression method in a frame based digital communication system, each frame including a predetermined number N of audio samples, thereby giving each frame N degrees of freedom, wherein a spectral subtraction function H(ω) is based on an estimate Φ v (ω) of a power spectral density of background noise of non-speech frames and an estimate Φ x (ω) of a power spectral density of speech frames comprising the steps of: approximating each speech frame by a parametric model that reduces the number of degrees of freedom to less than N; estimating said estimate Φ x (ω) of the power spectral density of each speech frame by a parametric power spectrum estimation method based on the approximative parametric model; and estimating said estimate Φ v (ω) of the power spectral density of each non-speech frame by a non-parametric power spectrum estimation method.
Claim 2
Dependent Claim
145 words
A spectral subtraction noise suppression method in a frame based digital communication system, each frame including a predetermined number N of audio samples, thereby giving each frame N degrees of freedom, wherein a spectral subtraction function H(ω) is based on an estimate Φ v (ω) of a power spectral density of background noise of non-speech frames and an estimate Φ x (ω) of a power spectral density of speech frames comprising the steps of: approximating each speech frame by a parametric model that reduces the number of degrees of freedom to less than N; estimating said estimate Φ x (ω) of the power spectral density of each speech frame by a parametric power spectrum estimation method based on the approximative parametric model; and estimating said estimate Φ v (ω) of the power spectral density of each non-speech frame by a non-parametric power spectrum estimation method.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein the approximative parametric model is an autoregressive (AR) model.
Claim 4
Dependent Claim
15 words
The method of claim 2, wherein the autoregressive (AR) model is approximately of order √N.
Claim 5
Dependent Claim
15 words
The method of claim 3, wherein the autoregressive (AR) model is approximately of order 10.
Claim 6
Dependent Claim
31 words
The method of claim 3, wherein the a spectral subtraction function H(ω) is in accordance with the formula: ##EQU45## where G(ω) is a weighting function and δ(ω) is a subtraction factor.
Claim 7
Dependent Claim
7 words
The method of claim 5, wherein G(ω)=1.
Claim 8
Dependent Claim
11 words
The method of claim 5, wherein δ(ω) is a constant ≦1.
Claim 9
Dependent Claim
19 words
The method of claim 3, wherein the a spectral subtraction function H(ω) is in accordance with the formula: ##EQU46##
Claim 10
Dependent Claim
18 words
The method of claim 3, wherein the a spectral subtraction function H(ω) is in accordance with the formula:
Claim 11
Dependent Claim
17 words
The method of claim 3, wherein the spectral subtraction function H(ω) is in accordance with the formula:
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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) | 2002-08-23 | 2003-02-22 | 2003-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-08-23 | 2007-02-22 | 2007-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-08-23 | 2011-02-22 | 2011-08-24 | $7700.00 | Window Closed / Lapsed |