Method and device for comparing signals to control transducers and transducer control system

• US 7,804,963 B2
• Filed: 05/30/2007
• Issued: 09/28/2010
• Est. Priority Date: 02/17/2000
• Status: Expired due to Fees

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Emerit, Marc, Thomas, Jean-Philippe
• Primary Examiner(s): Faulk; Devona E
• Application Number:
  US11/755,563
• Publication Number:
  US 20070286430A1
• Time in Patent Office: 1,217 Days
• Field of Search: 381/71.2, 381/71.12, 381/66, 381 55- 59, 381104-107, 381/111, 381/77, 381/96, 381/92, 381/122, 381/71.8, 379/202.01, 379/406.01, 379/388.02, 379/392.01, 348/14.08, 348/14.09, 348/14.1, 348/14.16
• US Class Current: 381/71.12
• 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

Abstract

A method of comparison between pieces of information characterizing reference values and pieces of information characterizing current values of sound-reproducing systems of a system of (n) microphones m_i and (p) speakers hp_j for the control of said sound-reproducing systems characterized in that: A: for each speaker hp_j, at least one sound signal S is sent on the speaker hp_j, for each microphone m_i, a piece of information hp_jm_i is retrieved, this piece of information characterizing the sound-reproducing system comprising the speaker hp_j and the microphone m_i, B: a reference matrix Q_r is saved, this reference matrix being constituted by all the pieces of reference information hp_jm_i obtained following the sending of the sound signal S, C: as soon as a comparison is to be made, the step A is run with a sound signal S′ to obtain current information on a matrix Q, D: the matrices Q and Q_r are compared.

Claims

1. A method for controlling a sound system by determining changes that occur between a current working state and a reference working state of the sound system, the method comprising:

(A) generating, for each speaker hp_j of a plurality of speakers, one after another, a first predetermined sound signal as an output signal of the speaker hp_j, and

retrieving, for each microphone m_i of a plurality of microphones, the output signal generated by the microphone in response to the first predetermined sound signal generated by each speaker hp_j, said sound system being in the reference working state;

(B) generating and saving a reference matrix Q_r of response data, said reference matrix Q_r comprising a response data hp_jm_i for each speaker hp_j and each microphone m_i, each response data hp_jm_i being characteristic of a sound-reproducing subsystem including the speaker hp_j and the microphone m_i in the reference working state, and each response data being determined by using the output signal retrieved for the microphone m_i in response to the first predetermined signal output by the speaker hp_i;

(C) determining changes over time between the current working state and the reference working state of the sound system by;

generating a current matrix Q of response data by performing (A) and (B) with a second predetermined sound signal, said sound system being in the current working state, and

comparing the current matrix Q with the reference matrix Q_r by computing from the reference matrix Q_r and the current matrix Q respectively, a mean value for each speaker hp_j or for each microphone m_i, and determining if a ratio of the respective mean values is outside of a predetermined range of values; and

(D) controlling the sound system by selectively adjusting the sound system in response to the changes determined in (C), when the ratio is outside of the predetermined range of values.

2. The method of claim 1, further comprising the step of:

processing the current matrix Q before comparing the current matrix Q with the reference matrix Q_r when the current response data is not directly comparable with the reference response data.

3. The method of claim 1, wherein further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of at least one of the reference matrix Q_r and the current matrix Q comprise a spectral response of each sound-reproducing subsystem that includes a speaker hp_j and a microphone m_i.

4. The method of claim 3, further comprising:

transmitting, in a frequency band with a predetermined width, the predetermined sound signals from the speakers hp_j, wherein the frequency band slides to sweep through a desired spectrum of frequencies.

5. The method of claim 1, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of at least one of the reference matrix Q_r and the current matrix Q comprise an impulse response of each sound-reproducing subsystem that includes a speaker hp_j and a microphone m_i.

6. The method of claim 1, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of at least one of the reference matrix Q_r and the current matrix Q comprise a transfer function of each sound-reproducing subsystem that includes a speaker hp_j and a microphone m_i.

7. The method of claim 1, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of at least one or the reference matrix Q_r and the current matrix Q comprise a gain between the microphones m_i and the speakers hp following the predetermined sound signals sent from the speakers hp_j.

8. The method of claim 1, wherein the plurality of microphones comprises n number of microphones, and wherein computing a mean value for each speaker hp_j and determining if a ratio of the respective mean values is outside of a predetermined range of values comprises:

from the matrices Q and Q_r, respectively,

computing the mean value corresponding to each speaker hp_j, respectively referenced as HP_jQ and HP_jQr, by

$1/n*\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>h<br><br><br><br>p_j<br><br>m_i,$

and wherein controlling the sound system comprises;

correcting a divergence corresponding to Hp_jQr/HP_jQ in each sound-reproducing subsystem comprising a speaker hp_j when the value Hp_jQ/HP_jQr is outside a predetermined speaker range FHP.

9. The method of claim 8, further comprising correcting a gain of the speaker hp_j for each sound-reproducing subsystem comprising a speaker hp_j.

10. The method of claim 8, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the respective response data of the matrices Q_r and Q comprise impulse responses of each sound-reproducing subsystem including a speaker hp_j and a microphone m_i, and wherein the response data correspond to the sound signals received by the microphone m_i from a direct path between the speaker hp_j and the microphone m_i.

11. The method of claim 8, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the respective response data of matrices Q_r and Q comprise impulse responses of each sound-reproducing subsystem including a speaker hp_j and a microphone m_i, and wherein the response data correspond to the sound signals received by the microphone m_i from paths with one or more reflections between the speaker hp_j and the microphone m_i.

12. The method of claim 1, wherein the plurality of speakers comprises p number of speakers, and wherein computing a mean value for each microphone m_i, and determining if a ratio of the respective mean values is outside of a predetermined range of values comprises:

from the matrices Q and Q_r, respectively,

computing the mean value corresponding to each microphone m_i, respectively referenced M_iQ and M_iQr, by

$1/p*\underset{j=1}{\overset{p}{\sum <br><br>}}<br><br><br><br>h<br><br><br><br>p_j<br><br>m_i,$

and wherein controlling the sound system comprises;

correcting a divergence corresponding to M_iQr/M_iQ in each sound-reproducing subsystem comprising a microphone m_i when the value of M_iQ/M_jQr is outside a predetermined microphone range FM.

13. The method of claim 12, further comprising correcting a gain of the microphone m_i for each sound-reproducing subsystem comprising a microphone m_i.

14. The method of claim 1, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of the matrices Q_r and Q represent delays between sending the predetermined sound signal from each speaker hp_j and reception of the sound signal by each microphone m_i.

15. The method of claim 1, wherein the plurality of speakers comprises p number of speakers, and wherein computing a mean value for each microphone m_i, and determining if a ratio of the respective mean values is outside of a predetermined range of values comprises:

determining, from said matrices Q and Q_r, respectively, the mean value corresponding to each microphone m_i, referenced respectively M_iQ and M_iQr, by

$1/p*\underset{j=1}{\overset{p}{\sum <br><br>}}<br><br><br><br>h<br><br><br><br>p_j<br><br>m_i,$

to obtain a signal-to-noise ratio M_iQr/M_iQ of the microphones, wherein the second predetermined sound signal used to constitute the current matrix Q is a silence signal.

16. The method of claim 1, further comprising:

remotely processing the response data of at least one of the matrices Q and Q_r through a telecommunications or computer network.

17. The method of claim 1, further comprising:

processing the response data in a local room, wherein the response data corresponds to predetermined sound signals constituting at least one of the matrices Q_r and Q and originating from a remote room connected to the local room through a telecommunications network.

18. The method of claim 1, wherein (C) further comprises:

generating the reference matrix Q_r of reference response data by performing (A) and (B) beforehand in the reference working state of the sound system, and generating the current matrix Q of current response data by performing (A) and (B) in the current working state, wherein the response data of matrices Q_r and Q represent an echo, and wherein the predetermined sound signals used to constitute the matrices originate from a remote room connected to a local room through a telecommunications network.

19. The method of claim 1, applied to a plurality of remote rooms, each remote room respectively equipped with a sound system connected to a multipoint bridge of a telecommunications network by at least one transmission channel, and wherein for each remote room the method further comprises:

transmitting said first predetermined sound signal, generated at (A) to be emitted by each speaker hp_j, to the remote room from said multipoint bridge through a first one of the at least one transmission channels of the telecommunications network; and

transmitting the output signal, retrieved at (A) for each microphone m_i, from the remote room to the multipoint bridge through a second one of the at least one transmission channels of the telecommunications network;

wherein (B) and (C) are performed in the multipoint bridge, each response data of the reference matrix Q_r and of the current matrix Q, for the respective remote room considered, being characteristic of a sound-reproducing subsystem that includes the first one of the at least one transmission channels from the respective remote room considered to the multipoint bridge, and the second one of the at least one transmission channels from the multipoint bridge to the respective remote room considered.

20. The method of claim 19, at least one of the predetermined sound signal used to generate matrix Q_r and the second predetermined sound signal used to generate matrix Q is selected from the group consisting of:

a white noise, a pink noise, a USASI noise, and a pseudo-random binary sequence.

21. The method of claim 19, wherein the second predetermined sound signal used to constitute the current matrix Q is the same as the first predetermined sound signal used to obtain the reference matrix Q_r.

22. The method of claim 1, wherein at least one of the first predetermined sound signal used to generate matrix Q_r and the second predetermined sound signal used to generate matrix Q is selected from the group consisting of:

a white noise, a pink noise, a USASI noise, and a pseudo-random binary sequence.

23. The method of claim 1, wherein the second predetermined sound signal used to constitute the current matrix Q is the same as the first predetermined sound signal used to obtain the reference matrix Q_r.

24. A device for controlling a sound system by determining changes that occur between a current working state and a reference working state of the sound system, the sound system comprising a plurality of microphones and a plurality of speakers, the device comprising:

means for generating, for each speaker hp_j of the plurality of speakers, one after another, a first predetermined sound signal as an output signal of the speaker hp_j when the sound system is in the reference working state, and for generating a second predetermined sound signal as an output signal of the speaker hp_j when the sound system is in the current working state;

means for retrieving, for each microphone m_i of the plurality of microphones, the output signal generated by the microphone m_i in response to either the first or second predetermined sound signal generated by each speaker hp_j;

means for generating and saving a reference matrix Qr of response data, said reference matrix Q_r comprising a response data hp_jm_i for each speaker hp_j and each microphone m_i, the response data being characteristic of a first sound-reproducing subsystem including the speaker hp_j and the microphone m_i in the reference working state, and the response data being determined by using the output signal retrieved for the microphone m_i in response to the first predetermined signal output by the speaker hp_j, and for generating and saving a current matrix Q of response data, said current matrix Q comprising a response data hp_jm_i for each speaker hp_j and each microphone m_i, the response data being characteristic of a second sound-reproducing subsystem including the speaker hp_j and the microphone m_i in the current working state, and the response data being determined by using the output signal retrieved for the microphone m_i in response to the second predetermined signal output by the speaker hp_j;

means for comparing the current matrix Q generated for the current working state of the sound system with the reference matrix Q_r generated beforehand for the reference working state of the sound system to determine changes over time between the current working state and the reference working state, by computing from the reference matrix Q_r and the current matrix Q respectively, a mean value for each speaker hp_j or for each microphone m_i, and determining if a ratio of the respective mean values is outside a predetermined range of values; and

means for controlling the sound system by selectively adjusting the sound system in response to a change determined as a result of comparing the current matrix Q and the reference matrix Q_r when the ratio is outside of the predetermined range of values.

25. The device of claim 24, wherein the first predetermined sound signal and the second predetermined sound signal are selected from the group consisting of:

a white noise, a pink noise, an USASI noise, and a pseudo-random binary sequence.

26. The device of claim 24, further comprising means to correct properties of a speaker hp_j and a microphone m_i of a subsystem comprising the speaker hp_j and the microphone m_i according to a difference determined between the current working state and the reference working state.

27. The device of claim 26, wherein a gain of the speaker hp_j is corrected in the subsystem comprising the speaker hp_j.

28. The device of claim 26, wherein a gain of the microphone m_i is corrected in the subsystem comprising the microphone m_i.

29. A control system for sound systems, comprising a plurality of devices according to claim 24, wherein the devices are distributed among a plurality of rooms, and wherein the control system comprises:

a high bit-rate telecommunications network connecting the plurality of rooms; and

means to centralize management of the devices.

30. The control system of claim 29, wherein the means to centralize management of the devices are located at a point of the telecommunications network connecting the plurality of rooms, each room being connected to the point of the telecommunications network by at least one transmission channels, the control system comprising means to selectively correct properties of a speaker hp_j and a microphone m_i of a sound-reproducing subsystem of a sound system in a room, the sound-reproducing subsystem including at least one transmission channel connecting the room to the point of the telecommunications network.