Systems and methods for monitoring cinema loudspeakers and compensating for quality problems

• US 9,648,437 B2
• Filed: 08/03/2010
• Issued: 05/09/2017
• Est. Priority Date: 08/03/2009
• Status: Active Grant

• Current Assignee: IMAX Corporation
• Original Assignee: IMAX Corporation
• Inventors: Tremblay, Denis G., Bonnick, Brian John
• Primary Examiner(s): Goins, Davetta W
• Assistant Examiner(s): GANMAVO, KUASSI A
• Application Number:
  US13/388,428
• Publication Number:
  US 20120140936A1
• Time in Patent Office: 2,471 Days
• Field of Search: 381 59, 381310, 381 1, 381 2, 381 17, 381 18, 381303, 381309, 381 97, 381 61, 381 66, 381 58, 381 63, 381 82, 381122, 704503, 704504, 700 94, 84630, 84610, 84626
• CPC Class Codes: H04R 2227/007 Electronic adaptation of audio signals to reverberation of the listening space for PA
• 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
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00
• CPC Class Codes: H04R 3/04 for correcting frequency response
• CPC Class Codes: H04S 3/002 Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution control circuits for electronic adaptation of the sound field H04S7/30
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

Systems and processes for compensating for changes in a theatre sound system positioned in a theatre are described. A subsequent response of a loudspeaker to a test signal is captured and compared to a previously obtained signature response of the loudspeaker to the test signal. An audio signal can be processed based on the comparison to compensate for changes to loudspeaker performance, or otherwise.

Claims

1. A method comprising:

capturing, by a microphone positioned at a suboptimal location that is outside of a patron-seating area in a theatre, a signature response of a loudspeaker in the theatre to a test signal, the signature response representing a desired response, at the suboptimal location, of the loudspeaker, the suboptimal location being a location other than an optimal location for a tuning microphone that is usable to determine an optimal response of the loudspeaker to a tuning test signal;

storing the signature response of the loudspeaker;

correlating the signature response to the optimal response, the signature response indicating what the optimal response should be at the suboptimal location of the microphone for the loudspeaker;

capturing, by the microphone positioned at the suboptimal location, a subsequent response of the loudspeaker to the test signal, the subsequent response representing a changed response, at the suboptimal location and at a time that is subsequent to capturing the signature response, of the loudspeaker;

determining a difference between the signature response and the subsequent response, the difference representing changes in loudspeaker response since capturing the signature response; and

compensating for the changes by modifying an audio signal based on the difference to generate a compensated audio signal and outputting the compensated audio signal by the loudspeaker such that a response to the compensated audio signal represents, in the patron-seating area of the theatre, the desired response by the loudspeaker.

2. The method of claim 1, wherein modifying the audio signal based on the difference to generate the compensated audio signal comprises:

determining an inverse of the difference; and

convolving the inverse of the difference with the audio signal.

3. The method of claim 1, wherein determining the difference between the signature response and the subsequent response comprises:

determining an inverse of the signature response;

using the inverse of the signature response to determine a correction to linearize the signature response to a predetermined limit;

applying the correction to the subsequent response to generate a corrected response; and

comparing the corrected response to the predetermined limit to determine the difference, the difference representing an amount by which to linearize the corrected response to the predetermined limit.

4. The method of claim 1, wherein the test signal comprises audio of at least one frequency in a hearing range of a human.

5. The method of claim 1, wherein the test signal comprises at least one of:

an impulse signal;

a chirp signal;

a maximum length sequence signal;

or

a swept sine signal.

6. The method of claim 1, wherein capturing the subsequent response of the loudspeaker to the test signal comprises capturing the subsequent response when at least one person is located in the theatre.

7. The method of claim 1, further comprising:

tuning a theatre sound system prior to determining the difference, the theatre sound system including the loudspeaker.

8. The method of claim 1, further comprising:

periodically determining differences and modifying motion picture audio signals based on the differences.

9. The method of claim 1, further comprising:

prior to (i) capturing the subsequent response of the loudspeaker to the test signal and (ii) determining the difference between the signature response and the subsequent response, tuning a theatre sound system that includes the loudspeaker by;

positioning the tuning microphone at the optimal location within the theatre; and

determining the optimal response of the loudspeaker to the tuning test signal provided to the loudspeaker; and

positioning the microphone at the suboptimal location.

10. A system comprising:

a microphone positionable at a suboptimal location that is outside of a patron-seating area in a theatre for (i) capturing a signature response of a loudspeaker in the theatre to a test signal, the signature response representing a desired response, at the suboptimal location, of the loudspeaker and (ii) capturing a subsequent response of the loudspeaker to the test signal at a time that is subsequent to capturing the signature response, the subsequent response representing a changed response, at the suboptimal location, of the loudspeaker, the suboptimal location being a location other than an optimal location for a tuning microphone that is usable to determine an optimal response of the loudspeaker to a tuning test signal; and

an equalizer unit adapted to (i) store the signature response of the loudspeaker, (ii) correlate the signature response to the optimal response, the signature response indicating what the optimal response should be at the suboptimal location of the microphone for the loudspeaker (iii) determine a difference between the signature response and the subsequent response, the difference representing changes in the loudspeaker since capturing the signature response,(iv) compensate for changes to the loudspeaker by modifying an audio signal based on the difference to generate a compensated audio signal and providing the compensated audio signal for output by the loudspeaker such that a response to the compensated audio signal represents the desired response by the loudspeaker in the patron-seating area of the theatre.

11. The system of claim 10, further comprising:

the microphone positioned at the suboptimal location that is within an audio dispersion path of the loudspeaker, the microphone being adapted to capture the signature response and the subsequent response and to output the signature response and the subsequent response to the equalizer unit.

12. The system of claim 10, further comprising an audio processing device, the audio processing device comprising:

a playback device capable of sourcing the audio signal;

an audio processor capable of synchronizing and processing the audio signal;

an amplifier capable of driving the loudspeaker; and

a user console capable of allowing a user to control the playback device and the audio processor,

wherein the equalizer unit is adapted to generate the test signal.

13. The system of claim 10, wherein the equalizer unit is adapted to:

in response to determining the subsequent response is between predetermined low limits, output to the loudspeaker the audio signal without being modified based on the difference; and

in response to determining the subsequent response exceeds a predetermined high limit, output a notification to a user interface for a theatre operator without modifying the audio signal based on the difference,

wherein the equalizer unit is adapted to modify the audio signal based on the difference and output to the loudspeaker the compensated audio signal modified based on the difference, in response to determining the subsequent response is between at least one predetermined low limit and at least one predetermined high limit.

14. The system of claim 10, wherein the equalizer unit is adapted to modify the audio signal using the difference by:

determining an inverse of the difference; and

convolving the inverse of the difference with the audio signal.

15. The system of claim 10, wherein the equalizer unit is capable of determining the difference by:

determining an inverse of the signature response;

using the inverse of the signature response to determine a correction to linearize the signature response to a predetermined limit;

applying the correction to the subsequent response to generate a corrected response; and

comparing the corrected response to the predetermined limit to determine the difference, the difference representing an amount by which to linearize the corrected response to the predetermined limit.

16. The system of claim 10, wherein the test signal comprises audio of at least one frequency in a hearing range of a human.

17. The system of claim 10, further comprising:

the tuning microphone positionable at the optimal location within the theatre,

wherein the equalizer unit is adapted to;

tune a theatre sound system that includes the loudspeaker by determining the optimal response of the loudspeaker to the tuning test signal provided to the loudspeaker prior to (i) the subsequent response of the loudspeaker to the test signal being captured and (ii) the difference between the signature response and the subsequent response being determined.

18. A theatre sound system comprising:

a loudspeaker positioned in an auditorium;

a microphone positioned in a suboptimal location that is outside of a patron-seating area in the auditorium and within an audio dispersion path associated with the loudspeaker, the microphone being adapted to capture (i) a signature response of the loudspeaker to a test signal, the signature response representing a desired response, at the suboptimal location, of the loudspeaker and (ii) a subsequent response of the loudspeaker to the test signal at a time that is subsequent to capturing the signature response, the subsequent response representing a changed response, at the suboptimal location, of the loudspeaker, the suboptimal location being a location other than an optimal location for a tuning microphone that is usable to determine an optimal response of the loudspeaker to a tuning test signal; and

an audio device adapted to (i) store the signature response of the loudspeaker, (ii) correlate the signature response to the optimal response, the signature response indicating what the optimal response should be at the suboptimal location of the microphone for the loudspeaker, (iii) generate a difference between the signature response and the subsequent response, and (iv) compensate for changes to the loudspeaker by modifying an audio signal of a motion picture based on the difference to generate a compensated signal,

wherein the loudspeaker is configured for outputting the compensated signal from the audio device such that a response to the compensated signal represents the desired response by the loudspeaker in the patron-seating area in the auditorium.

19. The system of claim 18, wherein the audio device is adapted to modify the audio signal of the motion picture based on the difference to generate the compensated signal by:

determining an inverse of the difference; and

convolving the inverse of the difference with the audio signal of the motion picture.

20. The system of claim 18, wherein the audio device is adapted to generate the difference by:

determining an inverse of the signature response;

using the inverse of the signature response to determine a correction to linearize the signature response to a predetermined limit;

applying the correction to the subsequent response to generate a corrected response; and

comparing the corrected response to the predetermined limit to determine the difference, the difference representing an amount by which to linearize the corrected response to the predetermined limit.

21. The theatre sound system of claim 18, further comprising:

the tuning microphone positionable at the optimal location within the auditorium,

wherein the audio device is adapted to;

tune the theatre sound system by determining the optimal response of the loudspeaker to the tuning test signal provided to the loudspeaker prior to (i) the subsequent response of the loudspeaker to the test signal being captured and (ii) the difference between the signature response and the subsequent response being determined.