Microphone placement for sound source direction estimation

Patent metadata

Field	Value
Publication number	US-9788109-B2
Application number	US-201514848703-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 9, 2015
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

Architectures of numbers of microphones and their positioning in a device for sound source direction estimation and source separation are presented. The directions of sources are front, back, left, right, top, and bottom of the device, and can be determined by amplitude and phase differences of microphone signals with proper microphone positioning. The source separation is to separate the sound coming from different directions from the mix of sources in microphone signals. This can be done with blind source separation (BSS), independent component analysis (ICA), and beamforming (BF) technologies. The device can perform many kinds of audio enhancements for the device. For example, it can perform noise reduction for communications; it can choose a source from a desired direction to perform speech recognition; and it can correct sound perceiving directions in microphones and generate desired sound images like stereo audio output. In addition, with source separation, 2.1, 5.1, 7.1, and other audio encoding and surround sound effects can be straightforward.

First claim

What is claimed is:

1. A process, comprising:
receiving microphone signals of sound received from two or more microphones on a device;
determining sound source locations relative to the device using the placement of two or more microphones on surfaces of the device and time of arrival and amplitude differences of sound received by the microphones;
dividing the space around the device into partitions using the determined sound source locations;
determining the number and type of applications for which the microphone signals are to be used and the number and type of output signals needed; and
using the determined partitions to select and process the microphone signals from desired partitions to approximately optimize signals for output to the determined one or more applications.

2. The process of claim 1 wherein dividing the space around the device into partitions further comprises:
from the direction of each microphone obtaining a subspace such that the time of arrival differences for sound from the subspace to the other microphones is greater than 0;
dividing each subspace into three additional subspaces based on the amplitude differences between the microphones;
combining common subspaces so that there are no overlapping subspaces;
combining the subspaces into a number of desired subspaces that contain desired subspace signals; and
outputting the desired subspace signals for the combined subspaces for use with the one or more applications.

3. The process of claim 1 wherein dividing the space around the device into partitions further comprises:
determining if an amplitude difference between the microphones is greater than a positive threshold, less than a negative threshold or between the positive threshold and the second negative threshold.

4. The process of claim 3 , further comprising determining a source signal in one or more partitions via a binary, a time-invariant or an adaptive solution.

5. The process of claim 3 , further comprising determining a subspace signal in one or more partitions, wherein coefficients of the subspace signal are obtained by using a probabilistic classifier that minimizes distortion of the subspace signal.

6. The process of claim 1 , wherein the number of applications is determined by determining the number of applications that run simultaneously and multiplying the determined number of applications by the outputs required for each application.

7. The process of claim 1 , wherein the signals output to the determined one or more applications are approximately optimized to perform noise reduction in a communications application.

8. The process of claim 1 , wherein the signals output to the determined one or more applications are approximately optimized to perform noise reduction in a speech recognition application.

9. The process of claim 1 , wherein the signals output to the determined one or more applications are approximately optimized to correct incorrectly perceived sound source directions.

10. A device, comprising:
a front-facing surface, a back-facing surface, a left-facing surface, a right-facing surface, a top-facing surface and bottom facing surface;
one microphone on one surface and another microphone on an opposing surface, wherein there is a distance between the two microphones measured from left to right when viewed from the surface having one of the microphones, the microphones generating audio signals in response to one or more external sound sources;
an audio processor configured to receive the audio signals from the microphones and determine the directions of the one or more external sound sources using their positioning on the surfaces of the device and time of arrival differences and amplitude differences between signals received by the microphone, wherein the sound source directions are determined by whether a time of arrival difference for a signal from one microphone to the other microphone is greater than a positive threshold, less than a negative threshold, or between the positive threshold and the negative thresholds.

11. The device of claim 10 , wherein the distance between the microphones is greater than a thickness of the device measured as the smallest distance between the two opposing surfaces.

12. The device of claim 10 , further comprising determining the sound source directions by determining whether a time of arrival difference for a signal from one microphone to the other microphone is greater than a positive threshold, less than a negative threshold, or between the positive threshold and the negative threshold.

13. The device of claim 10 , further comprising determining the directions by determining if an amplitude difference between the microphones is greater than a positive threshold, less than a negative threshold or between the positive threshold and the second negative threshold.

14. The device of claim 1 , further comprising additional microphones in the surfaces that increase a maximum number of sound source directions relative to the surfaces that can be determined.

15. A device comprising:
a front-facing surface, a back-facing surface, a left-facing surface, a right-facing surface, a top-facing surface and a bottom facing surface; and
one microphone on one surface and another microphone on an adjacent surface, wherein one of the microphones is offset such that it is closer to a surface of the device that is orthogonal to both of the surfaces containing the microphones, the microphones generating audio signals in response to one or more external sound sources;
an audio processor configured to receive the audio signals from the microphones and determines the direction of the one or more external sound sources in terms of the surfaces of the device by dividing the space around the device into partitions.

16. The device of claim 15 , wherein the direction of the sound relative to the surface is determined by using amplitude differences between signals generated by the microphones, and by using the time of arrival differences from the sound of an external sound source to the respective microphones.

17. The device of claim 16 , wherein if the amplitude is substantially the same in both microphones, and the time of arrival is sooner in a first one the microphones, then the sound source is directed towards an adjacent surface that is orthogonal to both of the surfaces containing the microphones, and wherein the adjacent surface is also closer to the first microphone.

18. The device of claim 16 , wherein if the amplitude is greater in a first one of the microphones, the time of arrival difference between the microphones is smaller than a threshold, and the time of arrival is sooner for the first microphone, then the sound source is directed towards a surface containing the first microphone.

19. The device of claim 16 , wherein if the amplitude is greater in a first one of the microphones, the time of arrival difference between the microphones is greater than a threshold, and the time of arrival is sooner for the first microphone, then the sound source is directed towards a surface opposite to the surface containing the other microphone.

20. The device of claim 15 , wherein the distance between the microphones is greater than a thickness of the device measured as the smallest distance between two opposing surfaces.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Lu Youhong
• Goh Chun Beng
• Beck Douglas L
• Hua Jia
• Khorosh Ilya

Classifications

• H04R29/005

  Microphone arrays · CPC title

• H04R3/005 Primary

  for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407) · CPC title

• H04R2201/401

  2D or 3D arrays of transducers · CPC title

• H04R5/027

  Spatial or constructional arrangements of microphones, e.g. in dummy heads · CPC title

• H04R1/406

  microphones · CPC title