Equalization setting determination for audio devices

• US 20070098188A1
• Filed: 11/02/2005
• Published: 05/03/2007
• Est. Priority Date: 11/02/2005
• Status: Abandoned Application

• Current Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Original Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Inventors: Felder, Matthew
• Application Number:
  US11/265,047
• Publication Number:
  US 20070098188A1
• Time in Patent Office: Days
• US Class Current: 381/107
• CPC Class Codes: H03G 3/007 Control dependent on the supply voltage
• CPC Class Codes: H03G 5/165 Equalizers; Volume or gain control in limited frequency bands

Abstract

A method for reducing distortion caused by clipping of lower frequency audio signals begins by monitoring a volume setting of an audio signal with respect to a range of volume settings to produce a monitored volume setting. The method continues by establishing an equalization setting based on the monitored volume setting.

Claims

1. A method comprises:

monitoring a volume setting of an audio signal with respect to a range of volume settings to produce a monitored volume setting; and

establishing an equalization setting based on the monitored volume setting.

2. The method of claim 1, wherein the establishing the equalization setting comprises:

determining whether low frequency distortion of the volume adjusted audio signal is possible based on the volume setting and the range of volume settings; and

when the low frequency distortion of the volume adjusted audio signal is possible, setting a low frequency range of the equalization setting at a level to avoid the low frequency distortion.

3. The method of claim 2 further comprises:

when the low frequency distortion of the volume adjusted audio signal is possible, setting at least one of mid and high frequency ranges of the equalization setting at a level above the level of the low frequency range of the equalization setting.

4. The method of claim 1, wherein the establishing the equalization setting comprises:

utilizing the volume setting as an index to a look up table; and

retrieving the equalization setting from the look up table.

5. The method of claim 1 further comprises:

monitoring a supply voltage to produce a monitored supply voltage; and

establishing the equalization setting based on the monitored volume setting and the monitored supply voltage.

6. The method of claim 1 further comprises:

monitoring a signal level of the audio signal to produce a monitored signal level; and

establishing the equalization setting based on the monitored volume setting and the monitored signal level.

7. The method of claim 1 further comprises:

amplifying the audio signal based on the monitored volume setting and the equalization setting.

8. A method comprises:

monitoring signal level of an audio signal;

determining whether the signal level compares unfavorably with a low frequency distortion threshold; and

when the signal level compares unfavorably to the low frequency distortion threshold, establishing an equalization setting to avoid low frequency distortion.

9. The method of claim 8, wherein the establishing the equalization setting comprises:

setting a low frequency range of the equalization setting at a level to avoid the low frequency distortion.

10. The method of claim 9, wherein the establishing the equalization setting further comprises:

setting at least one of mid and high frequency ranges of the equalization setting at a level above the level of the low frequency range of the equalization setting.

11. The method of claim 8 further comprises:

monitoring a supply voltage to produce a monitored supply voltage; and

adjusting the low frequency distortion threshold based on the monitored supply voltage.

12. The method of claim 8 further comprises:

comparing the signal level with a plurality of low frequency distortion thresholds, wherein the plurality of low frequency distortion thresholds include the low frequency distortion threshold;

determining a level of low frequency distortion based on the comparing of the signal level with the plurality of low frequency distortion thresholds; and

establishing the equalization setting based on the level of low frequency distortion.

13. An audio device comprises:

a processing module operably coupled to decode an audio file into a digital audio signal;

a digital to analog conversion module operably coupled to convert the digital audio signal into an analog audio signal; and

an audio output stage operably coupled to amplify the analog audio signal based on a volume setting and an equalization setting, wherein the processing module functions to;

monitor the volume setting of the analog audio signal with respect to a range of volume settings to produce a monitored volume setting; and

establish the equalization setting based on the monitored volume setting.

14. The audio device of claim 13, wherein the processing module establishes the equalization setting by:

determining whether low frequency distortion of the volume adjusted audio signal is possible based on the volume setting and the range of volume settings; and

when the low frequency distortion of the volume adjusted audio signal is possible, setting a low frequency range of the equalization setting at a level to avoid the low frequency distortion.

15. The audio device of claim 14, wherein the processing module further functions to:

when the low frequency distortion of the volume adjusted audio signal is possible, set at least one of mid and high frequency ranges of the equalization setting at a level above the level of the low frequency range of the equalization setting.

16. The audio device of claim 13, wherein the processing module establishes the equalization setting by:

utilizing the volume setting as an index to a look up table; and

retrieving the equalization setting from the look up table.

17. The audio device of claim 13, wherein the processing module functions to:

monitor a supply voltage to produce a monitored supply voltage; and

establish the equalization setting based on the monitored volume setting and the monitored supply voltage.

18. The audio device of claim 13, wherein the processing module functions to:

monitor a signal level of the audio signal to produce a monitored signal level; and

establish the equalization setting based on the monitored volume setting and the monitored signal level.

19. An audio device comprises:

a processing module operably coupled to decode an audio file into a digital audio signal;

a digital to analog conversion module operably coupled to convert the digital audio signal into an analog audio signal; and

an audio output stage operably coupled to amplify the analog audio signal based on a volume setting and an equalization setting, wherein the processing module functions to;

monitor signal level of the analog audio signal or of the digital audio signal;

determine whether the signal level compares unfavorably with a low frequency distortion threshold; and

when the signal level compares unfavorably to the low frequency distortion threshold, establish an equalization setting to avoid low frequency distortion.

20. The audio device of claim 19, wherein the processing module establishes the equalization setting by:

setting a low frequency range of the equalization setting at a level to avoid the low frequency distortion.

21. The audio device of claim 20, wherein processing module establishes the equalization setting by:

setting at least one of mid and high frequency ranges of the equalization setting at a level above the level of the low frequency range of the equalization setting.

22. The audio device of claim 19, wherein the processing module functions to:

monitor a supply voltage to produce a monitored supply voltage; and

adjust the low frequency distortion threshold based on the monitored supply voltage.

23. The audio device of claim 19, wherein the processing module functions to:

compare the signal level with a plurality of low frequency distortion thresholds, wherein the plurality of low frequency distortion thresholds include the low frequency distortion threshold;

determine a level of low frequency distortion based on the comparing of the signal level with the plurality of low frequency distortion thresholds; and

establish the equalization setting based on the level of low frequency distortion.