METHOD AND DEVICE FOR COMPARING SIGNALS TO CONTROL TRANSDUCERS AND TRANSDUCER CONTROL SYSTEM

• US 20070286430A1
• Filed: 05/30/2007
• Published: 12/13/2007
• Est. Priority Date: 02/17/2000
• Status: Active Grant

• Current Assignee: France Telecom SA (Orange S.A.)
• Original Assignee: Novagraaf Technologies - Cabinet Ballot
• Inventors: Thomas, Jean-Philippe, Emerit, Marc
• Granted Patent: US 7,804,963 B2
• Time in Patent Office: Days
• US Class Current: 381/71.120
• 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 sound system comprising (n) microphones m_i and (p) speakers hp_j, the microphones and the speakers selectively generating respective output signals, the method comprising:

(A) generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j, and

retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j;

(B) generating and saving a matrix of response data by using the output signals respectively generated by the (n) microphones m_i in response to the output signals respectively generated by the (p) speakers hp_j, each response data of the matrix being characteristic of a sound-reproducing subsystem which includes a microphone m_i and a speaker hp_j;

(C) constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (A) and (B) in the current working state;

(D) comparing the current matrix Q with the reference matrix Q_r to determine changes between the current working state and the reference working state of the sound system; and

(E) controlling the sound system by selectively adjusting the sound system in response to the changes determined in step (D).

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

processing the current matrix Q before step (D) when the current response data is not directly comparable with the reference response data.

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

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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 the step of:

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 step (C) further comprises:

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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 step (C) further comprises:

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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 step (C) further comprises:

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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_j following the predetermined sound signals sent from the speakers hp_j.

8. The method of claim 1, further comprising the steps of:

from the matrices Q and Q_r, respectively, computing a mean value corresponding to each speaker hp_j, respectively referenced as HP_jQ and HP_jQr, by

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

 

wherein hp_jm_i represents a response data for a sound-reproducing subsystem that includes a speaker hp_j and a microphone m_i; and

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 the step of correcting the gain of the speaker hp_j for each sound-reproducing subsystem comprising a speaker hp_j.

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

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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 step (C) further comprises:

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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, further comprising the steps of:

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

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

 

wherein hp_jm_i represents a response data for a sound-reproducing subsystem including a speaker hp_j and a microphone m_i; and

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

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

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

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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, further comprising the step of:

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

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

 

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

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

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 the step of:

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 step (C) further comprises:

constituting a reference matrix Q_r of reference response data by performing steps (A) and (B) beforehand in the reference working state of the sound system, and constituting a current matrix Q of current response data by running steps (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 comprising (n) microphones m_i and (p) speakers hp_j and 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 the steps of:

transmitting said predetermined sound signal, generated at step (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 step (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 steps (B) and (D) 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, wherein step (A) further comprises:

generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j, and retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j, wherein the predetermined sound signal used to generate at least one of matrix Q_r and 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 step (A) further comprises:

generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j, and retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j, wherein the sound signal used to constitute the current matrix Q is the same sound signal used to obtain the reference matrix Q_r.

22. The method of claim 1, wherein step (A) further comprises:

generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j, and retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j, wherein the predetermined sound signal used to generate at least one of matrix Q_r and 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 step (A) further comprises:

generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j, and retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j, wherein the sound signal used to constitute the current matrix Q is the same 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 (n) microphones m_i and (p) speakers hp_j, the microphones and speakers selectively generating respective output signals, the device comprising:

means for generating, for each speaker hp_j, a predetermined sound signal as an output signal of the speaker hp_j;

means for retrieving, for each microphone m_i, the output signal generated by the microphone in response to the predetermined sound signal generated by each speaker hp_j;

means for generating and saving a matrix of response data by using the output signals respectively generated by the (n) microphones m_i in response to the output signals respectively generated by the (p) speakers hp_j;

means for comparing a matrix Q generated for a current working state of the sound system with a matrix Q_r generated beforehand for the reference working state of the sound system; 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 matrix Q and the matrix Q_r.

25. The device of claim 24, wherein the predetermined sound signal is 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.