Updating modeling information based on online data gathering

• US 20060262942A1
• Filed: 04/17/2006
• Published: 11/23/2006
• Est. Priority Date: 10/15/2004
• Status: Active Grant

• Current Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Original Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Inventors: Oxford, William V.
• Granted Patent: US 7,760,887 B2
• Time in Patent Office: Days
• US Class Current: 381/66
• CPC Class Codes: H04M 1/6008 in the transmitter circuit
• CPC Class Codes: H04M 1/6033 for providing handsfree use or a loudspeaker mode in telephone sets arrangements for preventing acoustic echo H04M9/08
• 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 system may include a processor and memory. The processor may be configured to perform calibration measurements on the speaker even when the speaker is being used to conduct a live conversation. The processor may be configured to: provide a live output signal for transmission from a speaker; receive an input signal corresponding to the output signal; compute a midrange sensitivity and a lowpass sensitivity for a transfer function derived from a spectrum of the input signal and a spectrum of the output signal; subtract the midrange sensitivity from the lowpass sensitivity to obtain a speaker-related sensitivity; perform an iterative search for current parameters of a speaker model using the input signal spectrum, the output signal spectrum and the speaker-related sensitivity; and update averages of the speaker model parameters using the current parameter values. The parameter averages may be used to perform echo cancellation.

Claims

1. A method comprising:

(a) providing an output signal for transmission from a speaker, wherein the output signal carries live signal information from a remote source;

(b) receiving an input signal from a microphone;

(c) computing a midrange sensitivity and a lowpass sensitivity for a transfer function derived from a spectrum of a portion of the input signal and a spectrum of a portion of the output signal;

(d) subtracting the midrange sensitivity from the lowpass sensitivity to obtain a speaker-related sensitivity;

(e) performing an iterative search for current values of parameters of an input-output model of the speaker using the spectrum of the input signal portion, the spectrum of the output signal portion, and the speaker-related sensitivity; and

(f) updating averages of the parameters of the speaker input-output model using the current parameter values.

2. The method of claim 1 further comprising:

computing an average power signal on a stream of samples of the live signal information;

determining a window in time when the average power signal has remained greater than a power threshold for a predetermined amount of time;

wherein said portion of the output signal corresponding to samples of the live signal information during said window in time.

3. The method of claim 1, wherein the portion of the input signal corresponds to the portion of the output signal and a reverb tail of the portion of the output signal.

4. The method of claim 1 further comprising:

storing a plurality of portions of the output signal and corresponding portions of the input signal;

performing (c) through (f) a number of times, wherein each iteration of performing (c) through (f) operates on one of the output signal portions and the corresponding input signal portion.

5. The method of claim 1 further comprising:

comparing the updated parameter averages respectively to previous values of the parameter averages;

generating a problem report for the speaker in response to a determination that one or more of the updated parameter averages departs by more than a corresponding predetermined amount from the corresponding previous value.

6. The method of claim 1 further comprising:

applying one or more notch filters to the output signal prior to transmission from the speaker in order to remove one or more frequencies from the output signal.

7. The method of claim 1, wherein said updating the parameter averages using the current parameter values is performed according to an infinite impulse response (IIR) filtering scheme.

8. The method of claim 1 further comprising:

performing an iterative search for a current transfer function of the microphone using the spectrum of the input signal portion, the spectrum of the output signal portion, and the updated parameter averages;

updating an average microphone transfer function using the current microphone transfer function;

wherein the average microphone transfer function is usable to perform echo cancellation.

9. The method of claim 1, wherein (a) through (f) are performed by one or more processors in a speakerphone.

10. The method of claim 1, wherein the parameter averages of the speaker input-output model are usable to perform echo cancellation on the input signal.

11. The method of claim 1, wherein the input-output model of the speaker is a nonlinear model.

12. The method of claim 3, wherein the nonlinear model is a Volterra series model.

13. A computer-readable memory medium configured to store program instructions, wherein the program instructions are executable to implement:

(a) providing an output signal for transmission from a speaker, wherein the output signal carries live signal information from a remote source;

(b) receiving an input signal from a microphone;

(c) computing a midrange sensitivity and a lowpass sensitivity for a transfer function derived from a spectrum of a portion of the input signal and a spectrum of a portion of the output signal;

(d) subtracting the midrange sensitivity from the lowpass sensitivity to obtain a speaker-related sensitivity;

(e) performing an iterative search for current values of parameters of an input-output model of the speaker using the spectrum of the input signal portion, the spectrum of the output signal portion, and the speaker-related sensitivity; and

(f) updating averages of the parameters of the speaker input-output model using the current parameter values.

14. The method of claim 13, wherein the program instructions are executable to further implement:

computing an average power signal on a stream of samples of the live signal information;

determining a window in time when the average power signal has remained greater than a power threshold for a predetermined amount of time;

wherein said portion of the output signal corresponding to samples of the live signal information during said window in time.

15. The method of claim 13, wherein the portion of the input signal corresponds to the portion of the output signal and a reverb tail of the portion of the output signal.

16. The method of claim 13, wherein the program instructions are executable to further implement:

storing a plurality of portions of the output signal and corresponding portions of the input signal;

performing (c) through (f) a number of times, wherein each iteration of performing (c) through (f) operates on one of the output signal portions and the corresponding input signal portion.

17. The method of claim 13, wherein the program instructions are executable to further implement:

comparing the updated parameter averages respectively to previous values of the parameter averages;

generating a problem report for the speaker in response to a determination that one or more of the updated parameter averages departs by more than a corresponding predetermined amount from the corresponding previous value.

18. A system comprising:

a memory configured to store program instructions;

a processor configured to read and execute the program instructions from the memory, wherein the program instructions are executable by the processor to implement;

(a) providing an output signal for transmission from a speaker, wherein the output signal carries live signal information from a remote source;

(b) receiving an input signal from a microphone;

(c) computing a midrange sensitivity and a lowpass sensitivity for a transfer function derived from a spectrum of a portion of the input signal and a spectrum of a portion of the output signal;

(d) subtracting the midrange sensitivity from the lowpass sensitivity to obtain a speaker-related sensitivity;

(e) performing an iterative search for current values of parameters of an input-output model of the speaker using the spectrum of the input signal portion, the spectrum of the output signal portion, and the speaker-related sensitivity; and

(f) updating averages of the parameters of the speaker input-output model using the current parameter values.

19. The system of claim 18 further comprising the speaker and the microphone.

20. The system of claim 18, wherein the updated parameter averages are usable to perform echo cancellation on the input signal.