Devices, Methods and Computer Program Products for Controlling Loudness

• US 20140321670A1
• Filed: 04/26/2013
• Published: 10/30/2014
• Est. Priority Date: 04/26/2013
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nystrom, Martin, Smailagic, Sead
• Granted Patent: US 9,253,586 B2
• Time in Patent Office: Days
• US Class Current: 381/107
• CPC Class Codes: G10H 2250/161 Logarithmic functions, scaling or conversion, e.g. to reflect human auditory perception of loudness or frequency
• CPC Class Codes: H03G 3/20 Automatic control H03G3/005 takes precedence; combined with volume compression or expansion H03G7/00
• CPC Class Codes: H03G 5/165 Equalizers; Volume or gain control in limited frequency bands
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence

Abstract

A method by an electronic device for controlling a frequency response of audio output includes: receiving an audio signal at the device; estimating a sound pressure level of the audio signal based on one or more attributes or settings of the electronic device and/or the audio signal; generating values of an adaptive loudness control curve along a range of frequencies, wherein the adaptive loudness control curve is generated based on a difference between values of an equal loudness curve at the estimated sound pressure level along and values of an equal loudness curve at a reference sound pressure level; filtering the audio signal using values of the adaptive loudness control curve; and controlling output of the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies.

Claims

1. A method by an electronic device for controlling a frequency response of audio output, the method comprising:

receiving an audio signal at the device;

estimating a sound pressure level of the audio signal based on one or more attributes or settings of the electronic device and/or the audio signal;

generating values of an adaptive loudness control curve along a range of frequencies, wherein the adaptive loudness control curve is generated based on a difference between values of an equal loudness curve at the estimated sound pressure level along the range of frequencies and values of an equal loudness curve at a reference sound pressure level along the range of frequencies;

filtering the audio signal using values of the adaptive loudness control curve; and

controlling output of the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies.

2. The method of claim 1, wherein values of the equal loudness curve at the estimated sound pressure level and values of the equal loudness curve at the reference sound pressure level are values of equal loudness curves according to ISO 226:

2003.

3. The method of claim 1, comprising controlling the output of the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies independent of volume level.

4. The method of claim 1, comprising controlling the output of the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies independent of a level of content of the audio signal.

5. The method of claim 1, comprising:

generating a set of filter coefficients based on values of the adaptive loudness control curve; and

filtering the audio signal according to the generated set of filter coefficients.

6. The method of claim 1, wherein the one or more attributes or settings of the electronic device and/or the audio signal includes a volume setting that controls operation of the electronic device.

7. The method of claim 1, comprising determining a transducer factor associated with digital to analog conversion of the audio signal following the filtering, wherein the one or more attributes or settings of the electronic device and/or the audio signal includes the determined transducer factor.

8. The method of claim 1, comprising determining a gain that controls operation of at least one component of the electronic device, wherein the one or more attributes or settings of the electronic device includes the determined gain of the at least one component of the electronic device, wherein the at least one component of the electronic device includes at least one of an amplifier, a digital to analog converter, a processor, a filter and a loudspeaker.

9. The method of claim 1, wherein the one or more attributes or settings of the electronic device and/or the audio signal includes a level of the audio signal.

10. The method of claim 9, wherein the audio signal comprises a received or recorded signal, the method further comprising analyzing the received or recorded signal to obtain a time based average audio input as the level of the audio signal.

11. The method of claim 1, wherein the one or more attributes or settings of the electronic device and/or the audio signal includes an efficiency of a loudspeaker of the electronic device.

12. The method of claim 1, wherein the one or more attributes or settings of the electronic device and/or the audio signal comprises characteristics of a microphone signal.

13. The method of claim 1, wherein the reference sound pressure level is between about 90 dB and 100 dB.

14. The method of claim 1, wherein the audio signal comprises a recording, and wherein the reference sound pressure level is the actual sound pressure level at the recording.

15. An electronic device comprising:

an audio source; and

at least one processor configured to;

receive an audio signal from the audio source;

estimate a sound pressure level of the audio signal based on one or more attributes or settings of the electronic device and/or the audio signal; and

generate values of an adaptive loudness control curve along a range of frequencies, wherein the adaptive loudness control curve is generated based on a difference between values of an equal loudness curve at the estimated sound pressure level along the range of frequencies and values of an equal loudness curve at a reference sound pressure level along the range of frequencies.

16. The device of claim 15, further comprising a loudspeaker, wherein the at least one processor is configured to adaptively filter the audio signal using values of the generated adaptive loudness control curve, and wherein the loudspeaker is configured to output the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies.

17. The device of claim 15, further comprising a filter and a loudspeaker, wherein the filter is configured to receive the audio signal and filter the audio signal using values of the generated adaptive loudness control curve, and wherein the loudspeaker is configured to output the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies.

18. The device of claim 15, further comprising a loudspeaker, wherein the at least one processor is configured to electronically process the audio signal using a set of parameters that include electronic frequency response correction that is based on values of the generated adaptive loudness control curve to provide an audio drive signal to the loudspeaker.

19. The device of claim 15, wherein the device is a wireless communications terminal.

20. A computer program product for controlling frequency response for audio output by an electronic device, the computer program product comprising a non-transitory computer readable storage medium having encoded thereon instructions that, when executed on a computer, cause the computer to:

estimate a sound pressure level associated with an audio signal received at the electronic device based on one or more attributes or settings of the electronic device and/or the audio signal;

generate values of an adaptive loudness control curve along a range of frequencies, wherein the adaptive loudness control curve is generated based on a difference between values of an equal loudness curve at the estimated sound pressure level along the range of frequencies and values of an equal loudness curve at a reference sound pressure level along the range of frequencies;

filter the audio signal using values of the adaptive loudness control curve; and

control output of the filtered audio signal as an audio output having substantially the same loudness along the range of frequencies.