Beamforming apparatus and method based on long-term properties of sources of undesired noise affecting voice quality
View Patent ↗A beamforming technique for a microphone array is described to attenuate a source of undesired noise that is deemed the most limiting to audio quality in an acoustic environment. Possible sources of undesired noise include echo, background noise (stationary) and other interference signals (non-stationary). The beamforming technique is updated based on long-term evaluations. Once an evaluation occurs and a decision is made, the beamformer adapts with a maximum responsiveness and without intentional delay, and therefore not affecting the beamformer's tracking ability. When fixed beamforming is utilized, one of several fixed beamformers having different attenuation targets are selected to implement noise attenuation. When adaptive beamforming is utilized, the beamformer adapts whenever the selected target is deemed dominant.
1. A noise-reduction device, comprising:
a microphone array;
a codec configured to convert analog signals from the microphone array into digital signals; and
a processor configured to:
apply echo cancellation to the received digital signals to produce echo-cancelled signals;
detect a desired sound and a plurality of types of noise in the echo-cancelled signals;
determine a level of annoyance over a threshold period of time for each of the plurality of types of noise;
select one of the plurality of types of noise to attenuate based on the determined levels of annoyance; and
apply a beamforming technique to the digital signals to attenuate the selected noise type.
2. The noise-reduction device of claim 1 , wherein the threshold period of time is in the order of seconds.
3. The noise-reduction device of claim 1 , wherein the plurality of types of noise comprise two or more of echo, interference, and local noise.
4. The noise-reduction device of claim 3 , wherein the desired sound is pre-defined based on one of a spatial relationship relative to the microphone array, or speaker identification.
5. The noise-reduction device of claim 1 , wherein the processor is further configured to apply the beamforming technique utilizing a plurality of fixed beamformers, and wherein each of the plurality of fixed beamformers is configured to attenuate a particular acoustic characteristic.
6. The noise-reduction device of claim 1 , wherein the processor is further configured to apply the beamforming technique utilizing an adaptive beamformer to adapt to the selected type of noise.
7. The noise-reduction device of claim 1 , wherein the processor is further configured to select one of the plurality of types of noise to attenuate using decision logic, the decision logic being based on a linear function between the level of annoyance for each of the plurality of types of noise and the threshold period of time.
8. The noise-reduction device of claim 1 , wherein echo-cancellation information is used in determination of the level of annoyance for each of the plurality of types of noise.
9. The noise-reduction device of claim 8 , wherein noise-repression information is further used in determination of the level of annoyance for each of the plurality of types of noise.
10. A noise-reduction device, comprising:
a microphone array;
a codec configured to convert analog signals from the microphone array to digital signals; and
a processor, configured to:
receive the digital signals from the codec;
apply echo cancellation to the received digital signals to produce echo-cancelled signals;
detect, in the echo-cancelled signals, a plurality of sources comprising desired sound, echo, interference and noise;
determine a level of annoyance of echo, interference and noise over a threshold period of time;
select one of echo, interference and noise to attenuate based on the determined levels of annoyance; and
apply a beamforming technique based on the selection.
11. A method for improving audio quality in a communication device, comprising:
receiving digital signals based on analog signals captured by a microphone array;
applying echo cancellation to the received digital signals to produce echo-cancelled signals;
detecting a desired sound and a plurality of types of noise in the echo-cancelled signals;
determining a level of annoyance over a threshold period of time for each of the plurality of types of noise;
selecting one of the plurality of types of noise to attenuate based on the determined levels of annoyance; and
applying a beamforming technique to the digital signals to attenuate the selected noise type from the plurality of types of noise.
12. The method of claim 11 , wherein the threshold period of time is in the order of seconds.
13. The method of claim 11 , wherein the plurality of types of noise comprise two or more of echo, interference and noise.
14. The method of claim 13 , wherein the desired sound is pre-defined based on one of: a spatial relationship relative to the microphone array, or speaker identification on spatial properties or speaker identification.
15. The method of claim 11 , wherein applying the beamforming technique includes the use of a plurality of fixed beamformers, and wherein each of the plurality of fixed beamformers attenuates a particular acoustic characteristic.
16. The method of claim 11 , wherein applying the beamforming technique includes the use of an adaptive beam former to adapt to the selected one of the plurality of types of noise.
17. The method of claim 11 , further comprising:
selecting one of the plurality of types of noise to attenuate based on the application of decision logic, wherein the decision logic is based on a linear function between the level of annoyance for each of the plurality of types of undesired noise and the threshold period of time.
18. The method of claim 11 , wherein echo-cancellation information is used in determining the level of annoyance for each of the plurality of types of noise.
19. The method of claim 18 , wherein noise-repression information is further used in determining the level of annoyance for each of the plurality of types of undesired noise.
20. The noise-reduction device of claim 1 , wherein the processor is configured to:
select the one of the plurality of types of noise to attenuate based on a comparison of a signal strength of the one of the plurality of types of noise with a signal strength of another one of the plurality of types of noise over the threshold period of time.
21. The noise-reduction device of claim 1 , wherein the processor is configured to:
determine the level of annoyance for each of the plurality of types of noise based on corresponding signal strengths of the plurality of types of noise over the threshold period of time.
22. The noise-reduction device of claim 10 , wherein the processor is configured to:
determine the level of annoyance for echo, interference, and noise based on corresponding signal strengths of the echo, the interference, and the noise over the threshold period of time.
23. The method of claim 11 , wherein the determining the level of annoyance comprises:
determining the level of annoyance for each of the plurality of types of noise based on corresponding signal strengths of the plurality of types of noise over the threshold period of time.