Ambient noise compensation system robust to high excitation noise

• US 8,335,685 B2
• Filed: 05/22/2009
• Issued: 12/18/2012
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Limited (Canada) (Blackberry Limited)
• Inventors: Hetherington, Phillip A.
• Primary Examiner(s): PULLIAS, JESSE SCOTT
• Application Number:
  US12/471,093
• Publication Number:
  US 20090287482A1
• Time in Patent Office: 1,306 Days
• Field of Search: None
• US Class Current: 704/225
• CPC Class Codes: G10L 21/0208 Noise filtering
• 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

Abstract

A speech enhancement system controls the gain of an excitation signal to prevent uncontrolled gain adjustments. The system includes a first device that converts sound waves into operational signals. An ambient noise estimator is linked to the first device and an echo canceller. The ambient noise estimator estimates how loud a background noise would be near the first device before or after an echo cancellation. The system then compares the ambient noise estimate to a current ambient noise estimate near the first device to control a gain of an excitation signal.

Claims

1. A speech enhancement system, comprising:

a first device that converts sound waves into operational signals;

an ambient noise estimator coupled to the first device; and

an echo canceller coupled to the first device and the ambient noise estimator to dampen a sound;

where the ambient noise estimator estimates how loud a background noise resulting from an excitation signal played over a speaker would be in a signal captured by the first device, where the ambient noise estimator compares the background noise estimate resulting from the excitation signal to a current ambient noise estimate near the first device, and where the ambient noise estimator reduces a gain of the excitation signal or stops further increases in the gain of the excitation signal in response to a determination that the background noise estimate associated with the excitation signal is higher than the current ambient noise estimate by a predetermined level.

2. The speech enhancement system of claim 1 where a comparator compares estimates of the background noise and the current ambient noise estimate.

3. The speech enhancement system of claim 2 where the gain of the excitation signal is controlled at an output of a device that converts electric signals into an audible sound.

4. The speech enhancement system of claim 2 where the comparator is configured to differentiate between an ambient noise and a composite noise.

5. The speech enhancement system of claim 1 where the gain of the excitation signal is controlled at an output of a device that converts electric signals to an audible sound.

6. The speech enhancement system of claim 1 where the ambient noise estimator comprises a transducer.

7. The speech enhancement system of claim 1 further comprising a transceiver in communication with a sink that is remote from the first device and the echo canceller.

8. The speech enhancement system of claim 1 where the first device is compliant with a transceiver protocol of a remote source and a remote sink is compliant with a transceiver protocol of a transceiver that is local to, and receives an output from the echo canceller.

9. The speech enhancement system of claim 8 where the remote source and the remote sink comprises a unitary device.

10. The speech enhancement system of claim 8 where the transceiver and echo canceller comprises part of a hands free phone system.

11. The speech enhancement system of claim 1 where the ambient noise estimator is configured to estimate how loud the background noise would be near the first device based on an enclosure'"'"'s coupling factor and the excitation signal.

12. A speech enhancement system, comprising:

a first device that converts sound waves into operational signal;

an ambient noise estimator coupled to the first device; and

an echo canceller coupled to the first device and the ambient noise estimator to dampen a sound;

where the ambient noise estimator calculates an estimate of a background noise near the first device, where the ambient noise estimator calculates the estimate from an excitation signal and a coupling factor, and where the ambient noise estimator performs a comparison between the estimate and a current ambient noise estimate near the first device to control a gain of the excitation signal based on an outcome of the comparison; and

where the ambient noise estimator reduces the gain of the excitation signal or stops further increases in the gain of the excitation signal in response to a determination that the estimate from the excitation signal and the coupling factor is higher than the current ambient noise estimate by a predetermined level.

13. The speech enhancement system of claim 12 where a comparator compares estimates of the background noise and the current ambient noise estimate.

14. The speech enhancement system of claim 13 where the gain of the excitation signal is controlled at an output of a device that converts electric signals into an audible sound.

15. The speech enhancement system of claim 13 where the comparator is configured to differentiate between an ambient noise and a composite noise.

16. The speech enhancement system of claim 12 where the gain of the excitation signal is controlled at an output of a device that converts electric signals to an audible sound.

17. The speech enhancement system of claim 12 where the ambient noise estimator comprises a transducer.

18. The speech enhancement system of claim 12 further comprising a transceiver in communication with a sink that is remote from the first device and the echo canceller.

19. The speech enhancement system of claim 12 where the first device is compliant with a transceiver protocol of a remote source and a remote sink is compliant with a transceiver protocol of a transceiver that is local to, and receives an output from the echo canceller.

20. The speech enhancement system of claim 19 where the remote source and the remote sink comprise a unitary device.

21. The speech enhancement system of claim 19 where the transceiver and echo canceller comprise parts of a hands free phone system.

22. The speech enhancement system of claim 12 where the coupling factor comprises a room coupling factor that represents a ratio of excitation signal magnitude to microphone signal magnitude when only the excitation signal is playing out into an enclosure.

23. The speech enhancement system of claim 12 where the ambient noise estimator reduces the gain of the excitation signal in response to the determination that the estimate from the excitation signal and the coupling factor is higher than the current ambient noise estimate by the predetermined level.

24. The speech enhancement system of claim 12 where the ambient noise estimator stops further increases in the gain of the excitation signal in response to the determination that the estimate from the excitation signal and the coupling factor is higher than the current ambient noise estimate by the predetermined level.

25. The speech enhancement system of claim 12 where the ambient noise estimator calculates the estimate of the background noise near the first device after an echo cancellation by the echo canceller.

26. The speech enhancement system of claim 12 where the coupling factor comprises an error coupling factor that represents a ratio of excitation signal magnitude to error signal magnitude after a linear filtering device stage of the echo canceller.