System and method for robust simultaneous driver measurement for a speaker system

• US 9,723,420 B2
• Filed: 03/05/2014
• Issued: 08/01/2017
• Est. Priority Date: 03/06/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Saux, Tom-Davy, Family, Afrooz, Johnson, Martin E.
• Primary Examiner(s): Huber, Paul
• Application Number:
  US14/771,480
• Publication Number:
  US 20150382121A1
• Time in Patent Office: 1,245 Days
• Field of Search: None
• CPC Class Codes: H04R 2420/05 Detection of connection of loudspeakers or headphones to amplifiers
• 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: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04R 29/002 Loudspeaker arrays

Abstract

A system and method for measuring the performance of a plurality of transducers integrated in one or more loudspeakers is described. The method simultaneously drives each transducer to emit sounds corresponding to distinct orthogonal test signals. A listening device senses sounds produced by the orthogonal test signals and analyzes the sensed audio signal to determine the performance of each transducer. By using orthogonal test signals, the multiple transducers may be measured and/or characterized simultaneously and with limited affect from extraneous noises.

Claims

1. A method for measuring a performance of a plurality of transducers, comprising:

driving each transducer of the plurality of transducers simultaneously using separate orthogonal test signals;

sensing, by a listening device, sound produced by each transducer to produce a sensed audio signal;

retrieving the orthogonal test signals used to drive each transducer;

summing each orthogonal test signal with the sensed audio signal, to generate a cross-correlation signal for each transducer; and

determining the performance of each transducer of the plurality of transducers based on the generated cross-correlation signal for the transducer.

2. The method of claim 1, further comprising:

detecting a positive peak in one of the cross-correlation signals indicating the corresponding transducer is in-phase and emitting sound; and

comparing the detected peak in the cross-correlation signal with a set of parameters to determine the operating performance of the corresponding transducer.

3. The method of claim 2, wherein the set of parameters is a range.

4. The method of claim 1, further comprising:

detecting a trough in one of the cross-correlation signals; and

determining, in response to the detected trough, the transducer corresponding to the cross-correlation signal with the detected trough has a reversed polarity.

5. The method of claim 1, further comprising:

detecting noise on the order of √

{square root over (N)} in one of the cross-correlation signals, wherein N is a number of transducers in the plurality of transducers; and

determining, in response to the detected noise, the transducer corresponding to the cross-correlation signal with the detected noise is disconnected or dead.

6. The method of claim 1, further comprising:

detecting a positive peak in one of the cross-correlation signals indicating the transducer is in-phase and emitting sound; and

performing, in response to detection of the positive peak, additional tests on the cross-correlation signal with the detected positive peak to further determine the operating performance of the transducer corresponding to the cross-correlation signal with the detected positive peak.

7. The method of claim 6, wherein the additional tests include comparing the cross-correlation signal with the detected positive peak against a corresponding orthogonal test signal to determine a transfer function for the transducer.

8. The method of claim 1, wherein the transducers are integrated within a single speaker array.

9. The method of claim 1, wherein the transducers are integrated within multiple speaker units.

10. The method of claim 1, wherein the orthogonal test signals are beamformed audio signals.

11. A test receiver for measuring the performance of a plurality of transducers, comprising:

a microphone to sense sounds produced by orthogonal test signals simultaneously played through the plurality of transducers; and

a measurement unit to (i) retrieve the orthogonal test signals used to drive each transducer, (ii) sum each orthogonal test signal with the sensed audio signal to generate a cross-correlation signal for each transducer, and (iii) determine the performance of each transducer of the plurality of transducers based on the generated cross-correlation signal for the transducer.

12. The test receiver of claim 11, further comprising:

a memory unit to store the orthogonal test signals and each orthogonal test signal'"'"'s association with one of the transducers.

13. The test receiver of claim 12, wherein the association indicates which of the orthogonal test signals is played through each transducer.

14. The test receiver of claim 11, wherein the measurement unit is to further detect a positive peak in one of the cross-correlation signals indicating the corresponding transducer is in-phase and emitting sound and compare the detected peak in the cross-correlation signal with a set of parameters to determine the operating performance of the corresponding transducer.

15. The test receiver of claim 14, wherein the set of parameters is a range.

16. The test receiver of claim 11, wherein the measurement unit is to further detect a trough in one of the cross-correlation signals and determine, in response to the detected trough, the transducer corresponding to the cross-correlation signal with the detected trough has a reversed polarity.

17. The test receiver of claim 11, wherein the measurement unit is to further

detect noise on the order of √

{square root over (N)} in one of the cross-correlation signals, wherein N is a number of transducers in the plurality of transducers; and

determine, in response to the detected noise, the transducer corresponding to the cross-correlation signal with the detected noise is disconnected or dead.

18. The test receiver of claim 11, wherein the measurement unit is to further detect a positive peak in one of the cross-correlation signals indicating the corresponding transducer is in-phase and emitting sound and perform, in response to detection of the positive peak, additional tests on the cross-correlation signal with the detected positive peak to further determine the operating performance of the transducer corresponding to the cross-correlation signal with the detected positive peak.

19. The test receiver of claim 18, wherein the additional tests include comparing the cross-correlation signal with the detected positive peak against a corresponding orthogonal test signal to determine a transfer function for the transducer.

20. The test receiver of claim 11, further comprising:

a plurality of power amplifiers for driving each of the plurality of transducers to play the orthogonal test signals simultaneously.

21. An article of manufacture, comprising:

a non-transitory machine-readable storage medium that stores instructions which, when executed by a processor in a computer,

signal that each transducer of a plurality of transducers be driven simultaneously using separate orthogonal test signals; and

retrieve the orthogonal test signals used to drive each transducer;

generate a cross-correlation signal for each transducer, based on i) the orthogonal test signal used to drive the transducer and ii) the sensed audio signal; and

determine the performance of each transducer using the generated cross-correlation signal for the transducer.

22. The article of manufacture of claim 21, wherein the storage medium includes further instructions which, when executed by the processor,

detect a positive peak in one of the cross-correlation signals indicating the corresponding transducer is in-phase and emitting sound;

and

compare the detected peak in the cross-correlation signal with a set of parameters to determine the operating performance of the corresponding transducer.

23. The article of manufacture of claim 22, wherein the set of parameters is a range.

24. The article of manufacture of claim 21, wherein the storage medium includes further instructions which, when executed by the processor,

detect a trough in one of the cross-correlation signals;

and

determine, in response to the detected trough, the transducer corresponding to the cross-correlation signal with the detected trough has a reversed polarity.

25. The article of manufacture of claim 21, wherein the storage medium includes further instructions to which, when executed by the processor,

detect noise on the order of √

{square root over (N)} in one of the cross-correlation signals, wherein N is a number of transducers in the plurality of transducers; and

determine, in response to the detected noise, the transducer corresponding to the cross-correlation signal with the detected noise is disconnected or dead.

26. The article of manufacture of claim 21, wherein the storage medium includes further instructions which, when executed by the processor,

detect a positive peak in one of the cross-correlation signals indicating the transducer is in-phase and emitting sound;

and

perform, in response to detection of the positive peak, additional tests on the cross-correlation signal with the detected positive peak to further determine the operating performance of the transducer corresponding to the cross-correlation signal with the detected positive peak.

27. The article of manufacture of claim 21, wherein the additional tests include comparing the cross-correlation signal with the detected positive peak against a corresponding orthogonal test signal to determine a transfer function for the transducer.

28. The article of manufacture of claim 21, wherein the transducers are integrated within a single speaker array.

29. The article of manufacture of claim 21, wherein the transducers are integrated within multiple speaker units.

30. The article of manufacture of claim 21, wherein the orthogonal test signals are beamformed audio signals.