LOUDNESS MAXIMIZATION WITH CONSTRAINED LOUDSPEAKER EXCURSION

• US 20120179456A1
• Filed: 08/09/2011
• Published: 07/12/2012
• Est. Priority Date: 01/12/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ryu, Sang-Uk, Shin, Jongwon, Schevciw, Andre Gustavo P., Xiang, Pei, Silverstein, Roy
• Granted Patent: US 8,855,322 B2
• Time in Patent Office: Days
• US Class Current: 704/200.1
• CPC Class Codes: H04R 3/007 Protection circuits for transducers

Abstract

An original loudness level of an audio signal is maintained for a mobile device while maintaining sound quality as good as possible and protecting the loudspeaker used in the mobile device. The loudness of an audio (e.g., speech) signal may be maximized while controlling the excursion of the diaphragm of the loudspeaker (in a mobile device) to stay within the allowed range. In an implementation, the peak excursion is predicted (e.g., estimated) using the input signal and an excursion transfer function. The signal may then be modified to limit the excursion and to maximize loudness.

Claims

1. A method of constraining loudspeaker excursion in a mobile station, comprising:

receiving an input audio signal at the mobile station;

predicting an excursion of a loudspeaker of the mobile station;

performing signal processing on the input audio signal to limit the excursion of the loudspeaker using the input audio signal and the predicted excursion; and

outputting the signal processed input audio signal to the loudspeaker.

2. The method of claim 1, wherein predicting the excursion of the loudspeaker comprises filtering the input audio signal with the excursion transfer function of the loudspeaker.

3. The method of claim 1, wherein performing the signal processing maximizes the perceived loudness of the input audio signal.

4. The method of claim 3, wherein the perceived loudness of the input audio signal is based on an approximation of a psychoacoustic loudness model.

5. The method of claim 3, wherein the perceived loudness of the input audio signal is based on the subband energy of each equal rectangular band (ERB) of the input audio signal and the specific loudness at each ERB subband.

6. The method of claim 5, further comprising:

transforming the input audio signal into a plurality of subband signals in the ERB scale; and

determining the subband energy for each ERB subband.

7. The method of claim 6, further comprising approximating the specific loudness at each ERB subband based on a psychoacoustic loudness model.

8. The method of claim 5, further comprising determining a peak excursion for each ERB subband.

9. The method of claim 1, wherein performing the signal processing is performed in the frequency domain.

10. The method of claim 1, further comprising pre-processing the input audio signal using a limiter and a makeup gain prior to predicting the excursion of the loudspeaker.

11. The method of claim 1, wherein the mobile station comprises a mobile device, and the input audio signal comprises a speech signal.

12. An apparatus for constraining loudspeaker excursion in a mobile station, comprising:

means for receiving an input audio signal at the mobile station;

means for predicting an excursion of a loudspeaker of the mobile station;

means for performing signal processing on the input audio signal to limit the excursion of the loudspeaker using the input audio signal and the predicted excursion; and

means for outputting the signal processed input audio signal to the loudspeaker.

13. The apparatus of claim 12, wherein the means for predicting the excursion of the loudspeaker comprises means for filtering the input audio signal with the excursion transfer function of the loudspeaker.

14. The apparatus of claim 12, wherein the means for performing the signal processing maximizes the perceived loudness of the input audio signal.

15. The apparatus of claim 14, wherein the perceived loudness of the input audio signal is based on an approximation of a psychoacoustic loudness model.

16. The apparatus of claim 14, wherein the perceived loudness of the input audio signal is based on the subband energy of each equal rectangular band (ERB) of the input audio signal and the specific loudness at each ERB subband.

17. The apparatus of claim 16, further comprising:

means for transforming the input audio signal into a plurality of subband signals in the ERB scale; and

means for determining the subband energy for each ERB subband.

18. The apparatus of claim 17, further comprising means for approximating the specific loudness at each ERB subband based on a psychoacoustic loudness model.

19. The apparatus of claim 16, further comprising means for determining a peak excursion for each ERB subband.

20. The apparatus of claim 12, wherein performing the signal processing is performed in the frequency domain.

21. The apparatus of claim 12, further comprising means for pre-processing the input audio signal using a limiter and a makeup gain prior to predicting the excursion of the loudspeaker.

22. The apparatus of claim 12, wherein the mobile station comprises a mobile device, and the input audio signal comprises a speech signal.

23. A computer-readable medium comprising instructions that cause a computer to:

receive an input audio signal at a mobile station;

predict an excursion of a loudspeaker of the mobile station;

perform signal processing on the input audio signal to limit the excursion of the loudspeaker using the input audio signal and the predicted excursion; and

output the signal processed input audio signal to the loudspeaker.

24. The computer-readable medium of claim 23, wherein the instructions that cause the computer to predict the excursion of the loudspeaker comprise instructions that cause the computer to filter the input audio signal with the excursion transfer function of the loudspeaker.

25. The computer-readable medium of claim 23, wherein the instructions that cause the computer to perform the signal processing maximize the perceived loudness of the input audio signal.

26. The computer-readable medium of claim 25, wherein the perceived loudness of the input audio signal is based on an approximation of a psychoacoustic loudness model.

27. The computer-readable medium of claim 25, wherein the perceived loudness of the input audio signal is based on the subband energy of each equal rectangular band (ERB) of the input audio signal and the specific loudness at each ERB subband.

28. The computer-readable medium of claim 27, further comprising computer-executable instructions that cause the computer to:

transform the input audio signal into a plurality of subband signals in the ERB scale; and

determine the subband energy for each ERB subband.

29. The computer-readable medium of claim 28, further comprising computer-executable instructions that cause the computer to approximate the specific loudness at each ERB subband based on a psychoacoustic loudness model.

30. The computer-readable medium of claim 27, further comprising computer-executable instructions that cause the computer to determine a peak excursion for each ERB subband.

31. The computer-readable medium of claim 23, wherein performing the signal processing is performed in the frequency domain.

32. The computer-readable medium of claim 23, further comprising computer-executable instructions that cause the computer to pre-process the input audio signal using a limiter and a makeup gain prior to predicting the excursion of the loudspeaker.

33. The computer-readable medium of claim 23, wherein the mobile station comprises a mobile device, and the input audio signal comprises a speech signal.

34. An apparatus for constraining loudspeaker excursion in a mobile station, comprising:

an excursion predictor for receiving an input audio signal at the mobile station, and for predicting an excursion of a loudspeaker of the mobile station; and

an excursion limiting signal processor for performing signal processing on the input audio signal to limit the excursion of the loudspeaker using the input audio signal and the predicted excursion, and for outputting the signal processed input audio signal to the loudspeaker.

35. The apparatus of claim 34, wherein the excursion predictor comprises a filter for filtering the input audio signal with the excursion transfer function of the loudspeaker.

36. The apparatus of claim 34, wherein the excursion limiting signal processor maximizes the perceived loudness of the input audio signal.

37. The apparatus of claim 36, wherein the perceived loudness of the input audio signal is based on an approximation of a psychoacoustic loudness model.

38. The apparatus of claim 36, wherein the perceived loudness of the input audio signal is based on the subband energy of each equal rectangular band (ERB) of the input audio signal and the specific loudness at each ERB subband.

39. The apparatus of claim 38, wherein the excursion limiting signal processor transforms the input audio signal into a plurality of subband signals in the ERB scale, and determines the subband energy for each ERB subband.

40. The apparatus of claim 39, wherein the excursion limiting signal processor approximates the specific loudness at each ERB subband based on a psychoacoustic loudness model.

41. The apparatus of claim 38, wherein the excursion limiting signal processor determines a peak excursion for each ERB subband.

42. The apparatus of claim 34, wherein performing the signal processing is performed in the frequency domain.

43. The apparatus of claim 34, further comprising a pre-processor for pre-processing the input audio signal using a limiter and a makeup gain prior to predicting the excursion of the loudspeaker.

44. The apparatus of claim 34, wherein the mobile station comprises a mobile device, and the input audio signal comprises a speech signal.