Adaptive Noise Cancellation

• US 20090012786A1
• Filed: 07/02/2008
• Published: 01/08/2009
• Est. Priority Date: 07/06/2007
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Viswanathan, Vishu Ramamoorthy, Zhang, Xianxian, Unno, Takahiro
• Application Number:
  US12/167,026
• Publication Number:
  US 20090012786A1
• Time in Patent Office: Days
• US Class Current: 704/233
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

Speech-free noise estimation by cancellation of speech content from an audio input where the speech content is estimated by noise suppression. Adaptive noise cancellation with primary and noise-reference inputs and an adaptive noise cancellation filter from estimating primary noise from noise-reference input. Speech Suppressor (Noise Estimation) applied to noise-reference input provides speech-free noise estimates for noise cancellation in the primary input.

Claims

1. A method of speech-free noise estimation, comprising the steps of:

(a) sample and frame an audio input;

(b) apply noise suppression to the frames to estimate speech content of the frames;

(c) cancel the speech content from the frames to give a speech-free noise estimated frames.

2. A method of noise cancellation, comprising the steps of:

(a) sample and frame both a primary audio input and a noise-reference audio input;

(b) apply speech suppression to the noise-reference frames;

(c) apply a voice activity detector to the primary frames;

when there is no voice activity, update the coefficients of an adaptive noise cancellation (ANC) filter;

(d) apply the ANC filter to the speech-free noise estimate to get an estimate of the primary noise; and

(e) subtract the estimate of primary noise from the primary input to get the noise cancelled speech.

3. An adaptive audio noise canceller, comprising:

(a) a primary input and a noise-reference input;

(b) a speech suppressor coupled to the noise-reference input;

(c) a voice activity detector (VAD) coupled to the primary input; and

(d) an adaptive noise cancellation (ANC) filter coupled to the primary input, to the VAD, and to the speech suppressor, wherein the ANC filter is operable to;

(i) when the VAD indicates no voice activity, update filter coefficients of the ANC filter;

(ii) apply the ANC filter to the output of the speech suppressor to get an estimate of noise at the primary input; and

(iii) subtract the estimate of noise at the primary input from an input signal at the primary input.