Method and apparatus for automatically adjusting speaker and microphone gains within a mobile telephone

• US 6,744,882 B1
• Filed: 03/30/1999
• Issued: 06/01/2004
• Est. Priority Date: 07/23/1996
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Mauro, Anthony P., Dejaco, Andrew P., Gupta, Samir
• Primary Examiner(s): Tsang, Fan
• Assistant Examiner(s): Escalante, Ovidio
• Application Number:
  US09/281,564
• Time in Patent Office: 1,890 Days
• Field of Search: 379/387, 379/388, 379/390, 379/391, 379/395, 379/399, 379/404, 379/387.01, 379/388.03, 379/390.03, 379/399.01, 455/232.1, 455/234.1, 455/239.1, 455/240.1, 455/219, 455/220, 381/122, 381/104, 381/106, 381/107, 381/109, 381/55, 381/56, 381/57
• US Class Current: 379/387.01
• CPC Class Codes: H04M 1/6008 in the transmitter circuit
• CPC Class Codes: H04M 1/6016 in the receiver circuit

Abstract

The mobile telephone is provided with the capability for automatically adjusting the gain of a microphone of the telephone based upon the detected noise level in which the cellular telephone is operated. As the noise level increases, the gain of the microphone is automatically decreased, thereby compensating for the natural tendency of telephone users to speak more loudly in noisy environments. Also, by decreasing the microphone gain, any clipping that might otherwise occur as a result of the user speaking more loudly is avoided and the signal-to-noise ratio is not thereby decreased. Furthermore, because the microphone gain decreases, the volume level of the voice of the user as it is output from the other party'"'"'s telephone is not unduly loud. Hence, the other party need not manually decrease the speaker gain of his or her telephone. In the exemplary embodiment, the cellular telephone includes a digital signal processor configured or programmed to apply the detected noise level to look-up tables relating various noise levels to appropriate speaker and microphone gain levels. Also, in the exemplary embodiment, the mobile telephone includes a speaker and the gain of the speaker is adjusted to increase in response to an increase in the background noise level. A method of automatically adjusting the gain of speaker in a wireless communications device includes the steps of obtaining a digital value representing the available headroom, estimating the background noise level, and adjusting the volume based on the background noise estimate and the available headroom. Thus, for example, the need for manual volume control buttons on a cellular telephone is eliminated.

Claims

1. An apparatus for adjusting the gain of a speaker of a mobile telephone, said apparatus comprising:

means for detecting the background noise level of the environment in which the mobile telephone is operating, wherein the background noise level for a current frame of speech is a function of a background noise level of a past frame of speech and a frame energy level of the current frame of speech;

means for compressing a current frame of speech using a compression threshold value to limit signal values;

means for determining available headroom, the available headroom dependent on the compression threshold value;

means for determining a target speaker volume based on the background noise level;

means for comparing the available headroom to the target speaker volume; and

means for setting the gain of the speaker of the mobile telephone based upon comparing the available headroom to the target speaker volume.

2. An apparatus as in claim 1, further comprising:

means for setting a gain of a microphone of the mobile telephone based upon the background noise levels detected in the presence of speech.

3. An apparatus as in claim 2, wherein a decrease in the gain of the speaker corresponds to an increase in the gain of the microphone.

4. The apparatus of claim 2, wherein the means for setting the gain of the microphone operates to decrease the gain in response to an increase in background noise levels.

5. The apparatus of claim 2, wherein the means for setting the gain of the microphone operates to set the gain to a level inversely proportional to the background noise level.

6. An apparatus as in claim 1, wherein gain values for the speaker are stored in a look-up table.

7. An apparatus as in claim 1, further comprising:

means for generating a microphone gain adjustment of the telephone based upon a detected background noise level in the environment in which the telephone is operated; and

a microphone for receiving an acoustic speech signal and for amplifying the acoustic signal in accordance with said microphone gain adjustment.

8. The apparatus of claim 1, further comprising:

means for determining a compression threshold value,

wherein the means for comparing the available headroom to the target speaker volume, further comprises;

means for generating a sum of the compression threshold value and the available headroom and comparing the sum to the target speaker volume.

9. The apparatus as in claim 8, wherein the means for comparing the available headroom to the target speaker volume further comprises:

means for generating a digital headroom control parameter,

wherein the means for generating a sum of the compression threshold value to the available headroom comprises means for generating a sum of the compression threshold value and the digital headroom control parameter.

10. An apparatus as in claim 1, operable with an acoustic signal received by a microphone, further comprising:

a microphone gain control unit for amplifying the acoustic signal with a gain value; and

an adjustment unit configured to adjust the gain value based on the detected background noise level.

11. The apparatus of claim 10, wherein the adjustment unit operates to decrease the gain in response to an increase in background noise levels.

12. The apparatus of claim 10, wherein the adjustment unit operates to set the gain of the microphone to a level inversely proportional to the background noise level.

13. The apparatus of claim 10, wherein setting the gain of the speaker operates to increase the gain of the speaker in response to an increase in the background noise level.

14. The apparatus of claim 10, wherein the adjustment unit is a digital signal processor.

15. The apparatus of claim 14, wherein the digital signal processor unit includes a microphone gain lookup table.

16. The apparatus as in claim 1, wherein the means for determining a target speaker volume based on the background noise level comprises:

means for comparing the background noise level to a plurality of threshold values and determining a target speaker volume in response.

17. A method of automatically setting a volume level of a speaker of a communications device, comprising the steps of:

compressing a frame of speech using a compression threshold value to limit signal values;

obtaining a digital value representing an amount of available headroom, the available headroom dependent on the compression threshold value;

estimating a background noise level to generate a Background Noise Estimate (BNE);

determining a target speaker volume as a function of the BNE;

comparing the amount of available headroom to the target speaker volume; and

adjusting the volume level of the speaker in accordance with the comparing the amount of available headroom to the target speaker volume.

18. The method of claim 17, wherein the adjusting step comprises adjusting the volume level of the speaker in accordance with the digital value only if the result of the estimating step exceeds a predefined value.

19. The method of claim 17, further comprising the step of compensating for relative increases in the result of the estimating step during periods of silence.

20. The method as in claim 17, further comprising:

detecting the background noise level of the environment in which the communication device is operating; and

setting the gain of a microphone of the communication device based upon the detected background noise levels.

21. The method of claim 20, wherein the step of setting the gain of the microphone is performed to decrease the gain in response to an increase in background noise levels.

22. The method of claim 20, wherein the step of setting the gain of the microphone is performed to set the gain to a level inversely proportional to the background noise level.

23. The method of claim 20, further including the step of setting the gain of a speaker of the communication device based upon the background noise level.

24. The method of claim 23, wherein the step of setting the gain of the speaker of the communication device is performed to increase the gain in response to an increase in the background noise level.

25. A device for automatically setting a volume level of a speaker of a communications device, comprising:

means for compressing a frame of speech using a compression threshold value to limit signal values;

means for obtaining a digital value representing an amount of available headroom, the available headroom dependent on the compression threshold value;

means for estimating a background noise level to generate a Background Noise Estimate (BNE);

means for determining a target speaker volume as a function of the BNE;

means for comparing the amount of available headroom to the target speaker volume; and

means for adjusting the volume level of the speaker in accordance with the comparing the amount of available headroom to the target speaker volume.

26. The device of claim 25, wherein the means for adjusting comprises means for adjusting the volume level of the speaker in accordance with the digital value only if the background noise estimate exceeds a predefined value.

27. The device of claim 25, further comprising means for compensating for relative increases in the background noise estimate during periods of silence.

28. An automatic volume control device, comprising:

a compressor configured to provide a digital value representing an amount of available headroom, wherein the available headroom is a dynamic value resulting from compression processing of input signals; and

gain control logic coupled to the compressor and configured to receive the digital value from the compressor, the gain control logic further configured to receive a background noise estimate, generate a target speaker volume as a function of the background noise estimate, and adjust a volume level based on the target speaker volume and the amount of available headroom.

29. The automatic volume control device of claim 28, wherein the gain control logic is further configured to adjust the volume level only if the background noise estimate exceeds a predefined value.

30. The automatic volume control device of claim 28, further comprising logic configured to compensate for relative increases in the background noise estimate during periods of silence.