Noise reduction using correction vectors based on dynamic aspects of speech and noise normalization

• US 7,542,900 B2
• Filed: 05/05/2006
• Issued: 06/02/2009
• Est. Priority Date: 04/05/2002
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Deng, Li, Droppo, James G., Acero, Alejandro
• Primary Examiner(s): Hudspeth; David R
• Assistant Examiner(s): Serrou; Abdelali
• Application Number:
  US11/429,630
• Publication Number:
  US 20060206321A1
• Time in Patent Office: 1,124 Days
• Field of Search: 704226-228, 704/234, 704/231
• US Class Current: 704/226
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

A method and apparatus are provided for reducing noise in a signal. Under one aspect of the invention, a correction vector is selected based on a noisy feature vector that represents a noisy signal. The selected correction vector incorporates dynamic aspects of pattern signals. The selected correction vector is then added to the noisy feature vector to produce a cleaned feature vector. In other aspects of the invention, a noise value is produced from an estimate of the noise in a noisy signal. The noise value is subtracted from a value representing a portion of the noisy signal to produce a noise-normalized value. The noise-normalized value is used to select a correction value that is added to the noise-normalized value to produce a cleaned noise-normalized value. The noise value is then added to the cleaned noise-normalized value to produce a cleaned value representing a portion of a cleaned signal.

Claims

1. A computer-readable storage medium having computer-executable instructions stored thereon that when executed by a processor cause the processor to perform steps comprising:

forming a correction vector based on dynamic aspects of a signal, the correction vector comprising static coefficients, delta coefficients that describe rates of change of the static coefficients, and acceleration coefficients that describe rates of change of the delta coefficients; and

adding the correction vector to a feature vector having static coefficients, delta coefficients and acceleration coefficients and representing a portion of a noisy signal to produce a clean feature vector having static coefficients, delta coefficients and acceleration coefficients and representing a portion of a clean signal.

2. A computer-readable storage medium having computer-executable instructions stored thereon that when executed by a processor cause the processor to perform steps comprising:

for each noisy feature vector in a sequence of noisy feature vectors, identifying a most likely mixture component and an associated correction vector to form a sequence of correction vectors with one correction vector for each noisy feature vector;

applying the sequence of correction vectors to a filter to produce a sequence of filtered correction vectors; and

respectively adding each filtered correction vector in the sequence of filtered correction vectors to each respective noisy feature vector in the sequence of noisy feature vectors to form a sequence of noise reduced feature vectors.

3. The computer-readable medium of claim 2 wherein selecting a sequence of correction vectors comprises selecting a sequence of correction vectors having only static coefficients.

4. The computer-readable medium of claim 2 wherein the filter has a transfer function that is based on dynamic aspects of a signal.

5. The computer-readable medium of claim 4 wherein the filter is a time-invariant filter.