Adaptive noise state update for a voice activity detector

1. A method of updating a noise state of a voice activity detector (VAD) for indicating an active voice mode and an inactive voice mode, said method comprising:

receiving an input signal having a plurality of frames;

determining an elapsed time since the last update of said noise state;

updating said noise state of said VAD if said elapsed time exceeds a predetermined time;

determining an average minimum energy based on two or more of said plurality of frames;

determining a current minimum energy based on a current frame of said plurality of frames;

updating said noise state of said VAD if said average minimum energy is less than said current minimum energy; and

updating said noise state of said VAD if said average minimum energy is greater than said current minimum energy plus a first predetermined value.

2. The method of claim 1 , wherein said first predetermined value is 0.48828.

3. The method of claim 1 , wherein said predetermined time is about three seconds.

4. The method of claim 1 , wherein if said elapsed time exceeds said predetermined time, said updating said noise state of said VAD is delayed until an energy level of said input signal is below a predetermined energy threshold.

5. A method of updating a noise state of a voice activity detector (VAD) for indicating an active voice mode and an inactive voice mode, said method comprising:

receiving an input signal having a plurality of frames;

determining an average minimum energy based on two or more of said plurality of frames;

determining a current minimum energy based on a current frame of said plurality of frames;

updating said noise state of said VAD if said average minimum energy is less than said current minimum energy minus a first predetermined value; and

updating said noise state of said VAD if said average minimum energy is greater than said current minimum energy plus a second predetermined value.

6. The method of claim 5 , wherein said first predetermined value is zero.

7. The method of claim 5 , wherein said second predetermined value is 0.48828.

8. The method of claim 5 further comprising:

determining an elapsed time since the last update of said noise state; and

updating said noise state of said VAD if said elapsed time exceeds a predetermined time.

9. The method of claim 8 , wherein said predetermined time is about three seconds.

10. The method of claim 8 , wherein if said elapsed time exceeds said predetermined time, said updating said noise state of said VAD is delayed until an energy level of said input signal is below a predetermined energy threshold.

11. A voice activity detector (VAD) for indicating an active voice mode and an inactive voice mode, said VAD comprising:

an input configured to receive an input signal having a plurality of frames;

an output configured to indicate said active voice mode or said inactive voice mode;

wherein said VAD is configured to determine an elapsed time since the last update of a noise state of said VAD;

wherein said VAD is configured to update said noise state of said VAD if said elapsed time exceeds a predetermined time;

wherein said VAD is configured to determine an average minimum energy based on two or more of said plurality of frames;

wherein said VAD is configured to determine a current minimum energy based on a current frame of said plurality of frames;

wherein said VAD is configured to update said noise state of said VAD if said average minimum energy is less than said current minimum energy; and

wherein said VAD is configured to update said noise state of said VAD if said average minimum energy is greater than said current minimum energy plus a first predetermined value.

12. The VAD of claim 11 , wherein said first predetermined value is 0.48828.

13. The VAD of claim 11 , wherein said predetermined time is about three seconds.

14. The VAD of claim 11 , wherein if said elapsed time exceeds said predetermined time, said VAD is configured to delay updating said noise state of said VAD until an energy level of said input signal is below a predetermined energy threshold.

15. A voice activity detector (VAD) for indicating an active voice mode and an inactive voice mode, said VAD comprising:

an input configured to receive an input signal having a plurality of frames;

an output configured to indicate said active voice mode or said inactive voice mode;

wherein said VAD is configured to determine an average minimum energy based on two or more of said plurality of frames;

wherein said VAD is configured to determine a current minimum energy based on a current frame of said plurality of frames;

wherein said VAD is configured to update a noise state of said VAD if said average minimum energy is less than said current minimum energy minus a first predetermined value; and

wherein said VAD is configured to update said noise state of said VAD if said average minimum energy is greater than said current minimum energy plus a second predetermined value.

16. The VAD of claim 15 , wherein said first predetermined value is zero.

17. The VAD of claim 15 , wherein said second predetermined value is 0.48828.

18. The VAD of claim 15 , wherein said VAD is configured to determine an elapsed time since the last update of said noise state, and wherein said VAD is configured to update said noise state of said VAD if said elapsed time exceeds a predetermined time.

19. The VAD of claim 18 , wherein said predetermined time is about three seconds.

20. The VAD of claim 18 , wherein if said elapsed time exceeds said predetermined time, said VAD delays updating said noise state of said VAD until an energy level of said input signal is below a predetermined energy threshold.