Device And Method For Voice Activity Detection

• US 20080091421A1
• Filed: 06/08/2004
• Published: 04/17/2008
• Est. Priority Date: 06/17/2003
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Inventors: Gustavsson, Stefan
• Granted Patent: US 7,966,178 B2
• Time in Patent Office: Days
• US Class Current: 704/233
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A device includes a sound signal analyser configured to determine whether a sound signal comprises speech. The device further includes a microphone system configured to discriminate sounds emanating from sources located in different directions from the microphone system so that sounds only emanating from a range of directions are included as signals possibly containing speech.

Claims

1. A device for voice activity detections comprising:

a sound signal analyser configured to determine whether a sound signal comprises speech, comprising;

a microphone system configured to discriminate sounds emanating from sources located in different directions from the microphone system, wherein the microphone system is configured to determine the direction of a sound source causing sound signals, and is configured to further analyse the sound to determine whether the sound signal comprises speech, if the sounds emanate from a first range of directions, but to decide that the sound signal does not comprise speech, if the sounds emanate from a second, different range of directions.

2. A device according to claim 1, wherein the first range of directions is directed in a direction of an intended user'"'"'s mouth (3).

3. A device according to claim 2, wherein the microphone system comprises two microphone elements separated a distance and located on a line directed in the direction of an intended user'"'"'s mouth.

4. A device according to claim 3, wherein the first range of directions is defined as an area falling inside a cone with a cone angle α

, wherein 10°

<

α

<

30°

.

5. A device according to claim 4, wherein α

is approximately 25°

.

6. A device according to claim 2, wherein the microphone system comprises three microphone elements separated a distance and located in a plane directed in the direction of an intended user'"'"'s mouth.

7. A device according to claim 6, wherein two of said three microphone elements are separated a distance and located on a line directed perpendicular to the direction of an intended user'"'"'s mouth.

8. A device according to claim 2, wherein the microphone system comprises four microphone elements, located such that the fourth microphone is not located in the same plane as the three others.

9. A device according to claim 3, wherein the microphone elements are directional with a pattern having maximal sensitivity in the direction of an intended user'"'"'s mouth.

10. A device according to claim 1, wherein the microphone system comprises one directional microphone element together with one or more other microphone elements configured to remove the uncertainty in the direction of the sound source.

11. A device according to claim 10, wherein the directional microphone element is configured to measure a sound pressure level relative to the other microphone elements.

12. A device according to claim 10, wherein the device is a mobile apparatus.

13. A mobile apparatus according to claim 12, wherein the microphone elements are located at a lower edge of the apparatus.

14. A mobile apparatus according to claim 12, wherein a plurality of microphone elements are located at the lower edge of the apparatus and at least one microphone element is located at a distance from the lower edge.

15. A mobile apparatus according to any one of claims 12 to 14, wherein the mobile apparatus comprises a mobile radio terminal, a pager, a communicator, an electric organiser and/or a smartphone.

16. An accessory for a mobile apparatus, comprising:

a microphone system configured to discriminate sounds emanating from sources located in different directions from the microphone system, wherein the microphone system is configured to determine the direction of a sound source causing sound signals, and is configured to further analyse the sound to determine whether the sound signal comprises speech, if the sounds emanate from a first range of directions, but to decide that the sound signal does not comprise speech, if the sounds emanate from a second, different range of directions.

17. An accessory according to claim 16, wherein the direction of the first range of directions is adjustable.

18. An accessory according to claim 16, wherein the accessory is a hands-free kit.

19. An accessory according to claim 16, wherein the accessory in that it is a telephone conference microphone.

20. A method for voice activity detection, comprising:

receiving sound signals from a microphone system configured to discriminate sounds emanating from sources located in different directions from the microphone system;

determining the direction of the sound source causing the sound signals;

analyzing the sound signals to determine whether the sound signals comprise speech if the sound signals emanate from a first range of directions; and

determining that the sound signals to do not comprise speech if the sound signals emanate from a second different range of directions.

21. A method according to claim 20, wherein the first range of directions is directed in the direction of an intended user'"'"'s mouth.

22. A method according to claims 21, wherein the first range of directions is defined as an area falling inside a cone with a cone angle α

, wherein 10°

<

α

<

30°

.

23. A method according to claims 22, wherein α

is approximately 25°

.

24. A method according to claim 22, wherein the microphone system comprises at least two microphone elements located at a distance d from each other and located on a line directed in the direction of an intended user'"'"'s mouth, wherein the direction to the sound source θ

is calculated as

25. A method according to claim 20, further comprising:

using one directional microphone element together with one or more other microphone elements to reduce uncertainty in the direction of the sound source.

26. A method according to claim 25, further comprising:

using the directional microphone element to measure a sound pressure level relative to the other microphone element.