Detector and method for voice activity detection

1. A method in a first voice activity detector, VAD, for detecting voice activity in a received input signal, the method comprising:

receiving a signal from a primary voice detector of said first VAD indicative of a primary voice activity decision made by the primary voice detector regarding voice activity in said input signal, wherein the primary voice activity decision is an intermediate voice activity decision of said first VAD in the sense that the primary voice activity decision is made by the first VAD without having been processed by a hangover addition unit of said first VAD,

receiving one or more signals from one or more second VADs external to the first VAD each indicative of a voice activity decision made by a respective second VAD regarding voice activity in said input signal, each second VAD comprising its own primary voice detector and hangover addition unit distinct from that of said first VAD,

combining the voice activity decisions indicated in the signal received from the primary voice detector of said first VAD and the one or more signals received from the one or more second VADs to generate a modified primary voice activity decision, and

sending the modified primary voice activity decision to a hangover addition unit of said first VAD that is configured to make a final voice activity decision of said first VAD.

2. The method according to claim 1 , wherein the voice activity decisions in the signals received from the primary voice detector and the one or more second VADs are combined by a logical AND, the modified primary voice activity decision thereby indicating voice only if the signal from the primary voice detector and each signal from the one or more second VADs indicate voice.

3. The method according to claim 1 , wherein the voice activity decisions in the signals received from the primary voice detector and the one or more second VADs are combined by a logical OR, the modified primary voice activity decision thereby indicating voice if at least one signal of the signal from the primary voice detector and the one or more signals from the one or more second VADs indicate voice.

4. The method according to claim 1 , wherein at least one signal from a second VAD is a final voice activity decision made by that second VAD in the sense that the final voice activity decision is made by the second VAD after having been processed by the hangover addition unit of said second VAD.

5. The method according to claim 1 , wherein at least one signal from a second VAD is a primary voice activity decision made by a primary voice detector of that second VAD, the primary voice activity decision being an intermediate voice activity decision of the second VAD in the sense that the primary voice activity decision is made by the second VAD without having been processed by the hangover addition unit of said second VAD.

6. The method according to claim 1 , comprising receiving only one signal from one of said second VADs.

7. The method according to claim 1 , comprising receiving a plurality of signals from a plurality of said second VADs.

8. The method according to claim 1 , wherein the voice activity decisions indicated in the signals received from the primary voice detector and the one or more second VADs are combined in dependence on input signal properties.

9. The method according to claim 8 , wherein the input signal properties comprise at least one of estimated signal-to-noise-ratio and background characteristics.

10. A first voice activity detector, VAD, configured to detect voice activity in a received input signal, the first VAD comprising:

an input circuit configured to:

receive a signal from a primary voice detector of said first VAD indicative of a primary voice activity decision regarding voice activity in said input signal, wherein the primary voice activity decision is an intermediate voice activity decision of said first VAD in the sense that the primary voice activity decision is made by the first VAD without having been processed by a hangover addition unit of said first VAD, and

receive one or more signals from one or more second VADs external to the first VAD each indicative of a voice activity decision made by a respective second VAD regarding voice activity in said input signal, each second VAD comprising its own primary voice detector and hangover addition unit distinct from that of said first VAD,

a processor circuit configured to combine the voice activity decisions indicated in the signal received from the primary voice detector of said first VAD and the one or more signals received from the one or more second VADs to generate a modified primary voice activity decision, and

an output circuit configured to send the modified primary voice activity decision to a hangover addition unit of said first VAD that is configured to make a final voice activity decision of said first VAD.

11. The first VAD according to claim 10 , wherein the processor circuit is configured to combine the voice activity decisions in the signals received from the primary voice detector and the one or more second VADs by a logical AND, the modified primary voice activity decision thereby indicating voice only if the signal from the primary voice detector and each signal from the one or more second VADs indicate voice.

12. The first VAD according to claim 10 , wherein the processor circuit is configured to combine the voice activity decisions in the signals received from the primary voice detector and the one or more second VADs by a logical OR, the modified primary voice activity decision thereby indicating voice if at least one signal of the signal from the primary voice detector and the one or more signals from the one or more second VADs indicate voice.

13. The first VAD according to claim 10 , wherein at least one signal from a second VAD is a final voice activity decision made by that second VAD in the sense that the final voice activity decision is made by the second VAD after having been processed by the hangover addition unit of said second VAD.

14. The first VAD according to claim 10 , wherein at least one signal from a second VAD is a primary voice activity decision made by a primary voice detector of that second VAD, the primary voice activity decision being an intermediate voice activity decision of the second VAD in the sense that the primary voice activity decision is made by the second VAD without having been processed by the hangover addition unit of said second VAD.

15. The first VAD according to claim 10 , wherein the input circuit is configured to receive only one signal from one of said second VADs.

16. The first VAD according to claim 10 , wherein the input circuit is configured to receive a plurality of signals from a plurality of said second VADs.

17. The first VAD according to claim 10 , wherein the voice activity decisions indicated in the signals received from the primary voice detector and the one or more second VADs are combined in dependence on input signal properties.

18. The first VAD according to claim 17 , wherein the input signal properties comprise at least one of estimated signal-to-noise-ratio and background characteristics.

19. The method according to claim 1 , wherein at least one of the one or more second VADs is configured to generate lower activity or introduce less speech clipping than the first VAD under certain input conditions comprising one or more of a certain noise level, a certain signal-to-noise ratio, and a certain noise characteristic.

20. The method according to claim 1 , wherein, under certain input conditions, the primary voice activity decision from the first VAD's primary voice detector falsely indicates voice activity or clips speech, and wherein said combining is performed using combination logic that is adapted to said certain input conditions such that the one or more decisions from the one or more second VADs only modify the primary voice activity decision of the first VAD's primary voice detector under said certain input conditions, wherein said certain input conditions comprise at least one of a certain noise level, a certain signal-to-noise ratio, and a certain noise characteristic.

21. The method according to claim 1 , wherein said combining comprises combining the primary voice activity decision made by the primary voice detector of said first VAD, a primary voice activity decision made by the primary voice detector of a given one of the one or more second VADs, and a final voice activity decision output by the hangover addition unit of said given one of the one or more second VADs.

22. The method according to claim 1 , wherein said combining comprises combining the primary voice activity decision made by the primary voice detector of said first VAD and a primary voice activity decision made by the primary voice detector of one of the one or more second VADs using a first combination logic, and combining the result with a final voice activity decision output by the hangover addition unit of one of the one or more second VADs using a second combination logic different from the first combination logic.