Method and device for noise reduction control using microphone array

• US 8,942,976 B2
• Filed: 12/15/2010
• Issued: 01/27/2015
• Est. Priority Date: 12/28/2009
• Status: Active Grant

• Current Assignee: Weifang Goertek Microelectronics Co., Ltd. (Goertek Incorporated)
• Original Assignee: Goertek Incorporated
• Inventors: Li, Bo, Lou, Shasha, Li, Song
• Primary Examiner(s): COLUCCI, MICHAEL C
• Application Number:
  US13/499,948
• Publication Number:
  US 20120197638A1
• Time in Patent Office: 1,504 Days
• Field of Search: 704/226, 704/227, 704/233, 725/37, 381/71.11, 381/73.1, 381/92, 381/24.7, 372/19
• US Class Current: 704/226
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

The present invention provides a noise reduction control method using a microphone array and a noise reduction control device using a microphone array wherein the method comprises the steps of: S1: collecting, by the microphone array, acoustic signals; S2: estimating incidence angles of all acoustic signals of the microphone array; S3: conducting a statistics on signal components according to incidence angles; S4: determining a parameter α from a ratio of noise components according to the statistical result and using the parameter α as a control parameter for controlling an adaptive filter. With the present invention, space position information of the sound is obtained directly with the microphone array to control update of the adaptive filter more accurately, so as to eliminate noise, enhance SNR and protect speech quality well at the same time.

Claims

1. A noise reduction method using a microphone array, characterized by comprising steps of:

S1;

collecting, by the microphone array, acoustic signals;

S2;

estimating incidence angles of all acoustic signals collected by the microphone array, and;

distinguishing between target speech components and noise components based on the incidence angles, wherein the target speech components have incidence angles within an angle of protection, and wherein the noise components have incidence angles outside the angle or protection;

S3;

conducting a statistics on signal components according to the incidence angles;

S4;

determining a control parameter α

from a ratio of noise components according to the statistical result and using the parameter α

as a control parameter for updating an adaptive filter for reducing noise from the collected acoustic signals,

wherein the more noise components, the larger the control parameter α

, and the faster the updating of the adaptive filter,

wherein when all the collected acoustic signals are noise components, α

is determined to be 1, and the adaptive filter conducts the fastest update to suppress noise, and

wherein when all the collected acoustic signals are target speech components, α

is determined to be 0, and the adaptive filter stops updating weights of the filter to protect the target speech components from being damaged.

2. A noise reduction method using a microphone array of claim 1, said step of determining incidence angles of sounds comprises:

S201;

conducting frequency domain transformation or sub-band transformation on the acoustic signals;

S202;

calculating phase differences of each frequency bins or sub-bands of the signals collected by the microphone array and calculating relative time delays of each of the frequency bins or sub-bands of signals of the microphone array based on the phase differences;

S203;

calculating incidence angles of signals collected by the microphone array based on the relative time delays of each of the frequency bins or sub-bands.

3. A noise reduction method using a microphone array of claim 1 or 2, characterized in that in step S4, specifically, the adaptive filter is updated fast when there are only noises;

and the adaptive filter is updated slow when there is any target signal.

4. A noise reduction method using a microphone array of claim 3, characterized in that after step S2, it further comprises:

dividing an entire space into a protection area, a transition area and a suppression area, calculating a parameter β

according to an area in which said incidence angle is located and taking β

*α

as the control parameter of the adaptive filter,

wherein, β

=0 for incidence angles with in the protection area;

0<

β

<

1 for incidence angle angles within the transition area and β

=1 for incidence angles within the suppression area.

5. A noise reduction method using a microphone array of claim 2, characterized in that said step of converting acoustic signals into frequency domain further comprises:

S2011;

subjecting acoustic signals to framing;

S2012;

applying a window function to each frame of signal after framing;

S2013;

transforming windowed data into frequency domain by using DFT.

6. A noise reduction method using a microphone array of claim 5, characterized in that in step S2011,

the acoustic signal s_i is subjected to framing (i=1,2), with N sample points in each frame or a frame size of 10 ms˜

32 ms, letting a m^th frame of signal is d_i(m, n), wherein 0≦

n<

N, 0≦

m;

there are M overlapping sample points between two adjacent frames, with L=N-M sample points of new data for each frame;

the m^th frame of data is d_i(m, n)=s_i(m*L+n), wherein, s_i represents an acoustic signal, i indicates an index of a microphone, and di(m, n) represents the m^th signals of the acoustic signals s_i after being subjected to framing.

7. A noise reduction method using a microphone array of claim 6, characterized in that

assuming N=256, and overlapping number M=128˜

192.

8. A noise reduction device using a microphone array, comprising:

a microphone array for collecting acoustic signals;

a filtering control unit for determining incidence angles of all acoustic signals collected by the microphone array, conducting a statistics on signal components based on the incidence angles and then determining a control from a ratio of noise components according to the statistical result and using the parameter α

as a control parameter for updating an adaptive filter;

an adaptive filter for filtering out noises from the collected acoustic signals;

wherein the filtering control unit distinguishes between target speech components and noise components based on the incidence angles, wherein the target speech components have incidence angles within an angle of protection, wherein the noise components have incidence angles outside the angle or protection;

wherein the more noise components, the larger the control parameter α

, and the faster the updating of the adaptive filter,

wherein when all the collected acoustic signals are noise components, α

is determined to be 1, and the adaptive filter conducts the fastest update to suppress noise, and

wherein when all the collected acoustic signals are target speech components, α

is determined to be 0, and the adaptive filter stops updating weights of the filter to protect the target speech components from being damaged.

9. A noise reduction device using a microphone array of claim 8, characterized in that said filtering control unit comprises:

a DFT unit for discrete Fourier transforming acoustic signals into frequency domain;

a signal delay estimation unit for calculating phase differences of each frequency bins or sub-bands of the signals collected by the microphone array and calculating relative time delays of each frequency bins or sub-bands of the signals collected by the microphone array based on the phase differences;

a signal direction estimation unit for calculating incidence angles of the signals collected by the microphone array based on the relative time delays of each frequency bins or sub-bands;

a signal component statistics unit for conducting a statistics on components of target signal based on said incidence angles and distinguishing them to find out a target signal component and noise component, and determining the control parameter α

from a ratio of noise components according to the statistical result and using the parameter α

as a control parameter for controlling the adaptive filter.

10. A noise reduction device using a microphone array of claim 9, characterized in that said DFT unit comprises:

a framing unit for framing the acoustic signals;

a window function unit for applying a window function to each frame of signal after framing;

a DFT converting unit for transforming windowed data into frequency domain.

11. A noise reduction device using a microphone array of claim 9, characterized in that said signal component statistics unit is further configured for dividing an entire space into several areas, calculating a parameter β

according to an area in which said incidence angle is located, and taking β

*α

as the control parameter of the adaptive filter.

12. A noise reduction device using a microphone array of any one of claims 8-10, characterized in that said microphone array is completely comprised of omnidirectional microphones or comprised of omnidirectional microphones and monodirectional microphones or completely comprised of monodirectional microphones.