AUDIO SYSTEM EQUALIZATION FOR PORTABLE MEDIA PLAYBACK DEVICES

• US 20130066453A1
• Filed: 11/06/2012
• Published: 03/14/2013
• Est. Priority Date: 05/06/2010
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Seefeldt, Alan Jeffrey
• Granted Patent: US 9,307,340 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: H04R 2227/003 Digital PA systems using, e.g. LAN or internet
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

A method, an apparatus, a system, and instructions stored in a non-transitory computer-readable medium to instruct a processing system to carry out the method. The method includes applying corrective filters directly in a portable media device to correct, e.g., equalize for the overall system comprising the portable media device and the playback system to which it is attached. Also a method of determining the corrective filters by playing back one or more calibration signals on the playback system while recording the resulting sound field on the portable media device.

Claims

1. A method comprising:

recording on a portable media device a sound field resulting from one or more pre-defined calibration signals being played back on a particular playback system comprising a loudspeaker and external to a portable media device, the recording using a microphone built in or connected to the portable media device while the microphone is at a number of different desired listener locations of a particular listening arrangement, thereby measuring an impulse response of the loudspeaker at each of the number of different spatial locations in the particular listening arrangement;

averaging the measured impulse response to determine an averaged impulse response;

determining a particular set of one or more corrective filters at least to equalize for the particular playback system from the averaged impulse response and from a target response of the loudspeaker of the particular playback system, and

storing the data for the particular set of one or more corrective filters in or for the portable media device for the particular playback system,

wherein, while the portable media device is coupled to the particular playback system, the portable media device and particular playback system combination play back an audio signal in the particular listening arrangement while the portable media device applies the particular set of one or more corrective filters.

2. The method as recited in claim 1, further comprising applying critical frequency band smoothing to the averaged impulse response.

3. The method as recited in claim 1, wherein the particular set of corrective filters or the data therefor is stored in a storage subsystem included in the portable media device.

4. The method as recited in claim 1, wherein the storing the particular set of one or more corrective filters or the data therefor in or for the portable media device for the particular playback system includes storing an indicator that the particular set of one or more corrective filters is associated with the particular playback system.

5. The method as recited in claim 1, wherein the portable media device includes a user interface, and wherein the calibration method includes receiving on the user interface an indication from a user to carry out the recording, determining, and storing of the particular set of one or more corrective filters or the data therefor.

6. The method as recited in claim 1, wherein portable media device is coupled by a network to a remote processing system, and wherein the determining the particular set includes:

sending the recorded sound field or data related thereto to the remote processing system,

determining the particular set in the remote processing system, and

receiving the determined particular set or the data therefor via the network from the remote processing system.

7. The method as recited in claim 1, wherein the determining the particular set is carried out by one or more processors included in the portable media device.

8. The method as recited in claim 1, wherein the storing of the particular set of one or more corrective filters or the data therefor is into a storage subsystem remote from the portable media device, such that the particular set of correction filter or data therefor is loaded in the portable media device when or before the portable media device is coupled to the particular playback system for playback of an audio signal.

9. The method as recited in claim 1, wherein the portable media device is operable as a portable telephone.

10. A non-transitory computer-readable medium with instructions stored thereon that when executed by one or more processors, carry out a method comprising:

recording on a portable media device a sound field resulting from one or more pre-defined calibration signals being played back on a particular playback system comprising a loudspeaker and external to a portable media device, the recording using a microphone built in or connected to the portable media device while the microphone is at a number of different desired listener locations of a particular listening arrangement, thereby measuring an impulse response of the loudspeaker at each of the number of different spatial locations in the particular listening arrangement;

averaging the measured impulse response to determine an averaged impulse response;

determining a particular set of one or more corrective filters at least to equalize for the particular playback system from the averaged impulse response and from a target response of the loudspeaker of the particular playback system, and

storing the data for the particular set of one or more corrective filters in or for the portable media device for the particular playback system,

wherein, while the portable media device is coupled to the particular playback system, the portable media device and particular playback system combination play back an audio signal in the particular listening arrangement while the portable media device applies the particular set of one or more corrective filters.

11. The non-transitory computer-readable medium as recited in claim 10, further comprising applying critical frequency band smoothing to the averaged impulse response.

12. The non-transitory computer-readable medium as recited in claim 10, wherein the particular set of corrective filters or the data therefor is stored in a storage subsystem included in the portable media device.

13. The non-transitory computer-readable medium as recited in claim 10, wherein the storing the particular set of one or more corrective filters or the data therefor in or for the portable media device for the particular playback system includes storing an indicator that the particular set of one or more corrective filters is associated with the particular playback system.

14. The non-transitory computer-readable medium as recited in claim 10, wherein the portable media device includes a user interface, and wherein the calibration method includes receiving on the user interface an indication from a user to carry out the recording, determining, and storing of the particular set of one or more corrective filters or the data therefor.

15. The non-transitory computer-readable medium as recited in claim 10, wherein portable media device is coupled by a network to a remote processing system, and wherein the determining the particular set includes:

sending the recorded sound field or data related thereto to the remote processing system,

determining the particular set in the remote processing system, and

receiving the determined particular set or the data therefor via the network from the remote processing system.

16. The non-transitory computer-readable medium as recited in claim 10, wherein the determining the particular set is carried out by one or more processors included in the portable media device.

17. The non-transitory computer-readable medium as recited in claim 10, wherein the storing of the particular set of one or more corrective filters or the data therefor is into a storage subsystem remote from the portable media device, such that the particular set of correction filter or data therefor is loaded in the portable media device when or before the portable media device is coupled to the particular playback system for playback of an audio signal.

18. A portable media device comprising:

a playback subsystem configured to play back a selected audio signal;

a filter subsystem coupled to the playback subsystem and configured to apply a set of one or more corrective filters to an audio signal during playback of the audio signal;

a coupling configured to couple the portable media device to a matching coupling included in a playback system;

wherein the playback system comprises a loudspeaker and is external to the portable media device;

a user interface configured to accept input from a user; and

a microphone or a coupling to a microphone;

wherein the filter subsystem is configured to apply a particular set of one or more corrective filters associated with a particular playback system and particular listening arrangement during playback of an audio signal via the particular playback system when the portable media device is coupled to the particular playback system in the particular listening arrangement,

wherein the portable media device is configured to determine the particular set of one or more corrective filters by a calibration process that includes

recording a sound field resulting from one or more pre-defined calibration signals being played back on the particular playback system, the recording using the microphone in or connected to the portable media device while the microphone is at a number of different desired listener locations of the particular listening arrangement, thereby measuring an impulse response of the loudspeaker at each of the number of different spatial locations in the particular listening arrangement;

averaging the measured impulse response to determine an averaged impulse response;

determining the particular set of one or more corrective filters at least to equalize for the particular playback system from the averaged impulse response and from a target response of the loudspeaker of the particular playback system; and

storing the data for the particular set of one or more corrective filters in or for the portable media device for the particular playback system.

19. The portable media device as recited in claim 18, further comprising:

at least one processor; and

a storage subsystem coupled to the filter subsystem and to the at least one processor,

wherein applying the particular set of one or more corrective filters includes digitally processing digital signals on at least one of the one or more processors.

20. The portable media device as recited in claim 18, wherein the storing the particular set of one or more corrective filters or the data therefore in or for the portable media device for the particular playback system includes storing an indicator that the particular set of one or more corrective filters is associated with the particular playback system.

21. The portable media device as recited in claim 18, wherein the portable media device is configured to receive on the user interface an indication from a user to carry out the recording, determining, and storing of the particular set of one or more corrective filters or the data therefor.

22. The portable media device as recited in claim 18, wherein the portable media device includes a network interface to couple the portable media device to a remote processing system via a network, and wherein the portable media device is configured, for the determining the particular set, to:

send the recorded sound field or data related thereto to the remote processing system such that the remote processing system can determine the particular set, and to receiving the determined particular set or the data therefor via the network from the remote processing system.

23. The portable media device as recited in claim 18, wherein the analyzing the recording to determine the particular set is carried out by the at least one processor.

24. The portable media device as recited in claim 18, comprising a components to enable the portable media device to operate as a portable telephone.

25. A method of operating a portable media device operate as a portable telephone, the method comprising

while the portable media device is coupled to a particular playback system, playing back an audio signal on the portable media device and particular playback system combination in a particular listening arrangement while the portable media device applies a particular set of one or more corrective filters selected from a pre-stored collection of one or more sets of corrective filters or the data therefor,

wherein the collection of one or more sets of corrective filters or the data therefor is pre-stored in or for the portable media device, and each of one or more sets of the collection is associated with a corresponding listening arrangement and a corresponding playback system, and

wherein the particular set of one or more corrective filters is determined by a calibration process that includes,

recording on the portable media device a sound field resulting from one or more pre-defined calibration signals being played back on the particular playback system comprising a loudspeaker and external to a portable media device, the recording using a microphone built in or connected to the portable media device while the microphone is at one or more desired listener locations of the particular listening arrangement to measure an impulse response of the loudspeaker at each of the number of different spatial locations in the particular listening arrangement,

analyzing the recording of the sound field, including averaging the measured impulse response to determine an averaged impulse response, and determining the particular set of one or more corrective filters at least to equalize for the particular playback system, and

storing the data for the particular set of one or more corrective filters in or for the portable media device for the particular playback system.

26. The method as recited in claim 25, wherein the analyzing further comprises comprising applying critical frequency band smoothing to the averaged impulse response.

27. The method as recited in claim 25, wherein the collection of one or more sets of corrective filters or the data therefor is stored in a storage subsystem included in the portable media device.

28. The method as recited in claim 25, further comprising the portable media device receiving an indication from the particular playback system indicating that particular portable media device is coupled to the particular playback system, and responsive to the indication, the portable media device automatically selecting the particular set of one or more corrective filters associated with the particular portable media device for playback.

29. The method as recited in claim 25, wherein the storing the particular set of one or more corrective filters or the data therefore in or for the portable media device for the particular playback system includes storing an indicator that the particular set of one or more corrective filters is associated with the particular playback system.

30. The method as recited in claim 25, wherein portable media device is coupled by a network to a remote processing system, and wherein the analyzing the recording to determine the particular set includes:

sending the recorded sound field or data related thereto to the remote processing system,

determining the particular set in the remote processing system, and

receiving the determined particular set or the data therefor via the network from the remote processing system.

31. The method as recited in claim 25, wherein the analyzing the recording to determine the particular set is carried out by one or more processors included in the portable media device.