Sound canceling systems and methods

• US 7,835,529 B2
• Filed: 03/17/2004
• Issued: 11/16/2010
• Est. Priority Date: 03/19/2003
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Hernandez, Walter C., Kemp, Mathieu, Vosburgh, Frederick
• Primary Examiner(s): Chin; Vivian
• Assistant Examiner(s): MONIKANG, GEORGE C
• Application Number:
  US10/802,388
• Publication Number:
  US 20040234080A1
• Time in Patent Office: 2,435 Days
• Field of Search: 381/71.1, 381/71.11, 381/77, 381/71.2, 381/71.6, 381/71.8, 381/71.9, 600/586, 600/590
• US Class Current: 381/71.2
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone

Abstract

A system for sound cancellation includes a source microphone for detecting sound and a speaker for broadcasting a canceling sound with respect to a cancellation location. A computational module is in communication with the source microphone and the speaker. The computational module is configured to receive a signal from the source microphone, identify a cancellation signal using a predetermined adaptive filtering function responsive to acoustics of the cancellation location, and transmit a cancellation signal to the speaker.

Claims

1. A system for sound cancellation comprising:

a source microphone for detecting sound propagating from a mobile sound source remote from the source microphone;

a source localizing sensor for determining a current location of the sound source;

at least two speakers configured to direct a canceling sound toward a mobile cancellation location that is spatially remote from the sound source and the speakers,

a cancellation space localizing sensor for determining a current location of the mobile cancellation space; and

a computational module in communication with the source microphone, the source localizing sensor, the speakers, and the cancellation space localizing sensor, the computational module including a memory storing a situational transfer function of individual transfer functions, each individual transfer function corresponding to at least a sound source location and a cancellation space location, the computational module configured to receive a signal from the microphone, to identify at least one current individual transfer function corresponding to the current location of the sound source and the current location of the cancellation location, and to control the speakers to transmit a cancellation sound signal based on the at least one current individual transfer function to the speakers, wherein the situational transfer function includes a situational transfer matrix function, W,

W=1/(d−

c*e)

wherein c is a transfer function for sound propagation from the sound source to the source microphone, e is a transfer function for sound propagation from the speaker to the cancellation location, and d is a transfer function for sound propagation from the source microphone to the speaker, and the * operator denotes mathematical convolution.

2. The system of claim 1, further comprising a training sub-system having at least one training microphone that can be placed at the cancellation location.

3. The system of claim 1, further comprising a sound velocity and/or temperature sensor in communication with the computational module, wherein the predetermined adaptive filtering function is responsive to the temperature of the acoustic environment.

4. The system of claim 2, wherein the situational transfer function is determined by receiving a first sound input from the source microphone, receiving a second sound input from the training microphone, and then determining the situational transfer function, wherein the predetermined adaptive filtering function is adaptive to a sound transformation between the source microphone signal and the training microphone signal.

5. The system of claim 1, wherein the situational transfer function comprises a function that identifies a sound transformation between the source microphone and the cancellation location without contemporaneous sound receiving at the cancellation location.

6. The system in claim 1, wherein the source microphone comprises a plurality of source microphones.

7. The system of claim 1, wherein the speaker is a parametric speaker for broadcasting ultrasonic sound, the parametric speaker configured to broadcast a localized cancellation sound at the cancellation location.

8. The system of claim 1, wherein the speaker comprises a plurality of speakers.

9. The system of claim 1 further comprising:

a parametric speaker configured to transmit a canceling sound configured to cancel the detected sound such that the canceling sound is localized with respect to the cancellation location.

10. The system of claim 9, wherein the parametric speaker produces the canceling sound with an interaction between two or more ultrasonic signals.

11. The system of claim 9, wherein the parametric speaker produces the canceling sound by nonlinear interaction of an ultrasonic signal with air.

12. The system of claim 1, wherein the sound source comprises a snoring individual and the speaker spaced apart from the snoring individual.

13. The system of claim 1, wherein the situational transfer function is determined using convolution of the individual transfer functions, and each of the individual transfer functions is configured to characterize propagation of sound with respect to a pair of spaced apart transducers comprising at least one of a speaker, a microphone and/or a velocimeter.

14. The system of claim 1, wherein the at least two speakers are stationary.

15. The system of claim 2, wherein the at least one training microphone is configured to be removed from the cancellation space during transmission of the cancellation signal.

16. The system of claim 1, wherein the situational transfer function comprises a locations-representative situational transfer function representative of a sound source location and a cancellation location.

17. The system of claim 1, wherein the situational transfer function is provided by convolution of individual transfer functions representative of sound propagation between individual speakers, microphones and/or locations.

18. The system of claim 17, wherein the situational transfer function comprises at least one individual transfer function representative of cross talk between the speakers and the microphone.

19. The system of claim 4, wherein the received first sound input comprises undesirable sound from at least one cancellation speaker.

20. The system of claim 1, wherein the individual transfer functions are representative of cross talk and are invariant among the plurality of situational transfer functions.

21. The system of claim 2, wherein the at least one training microphone is deployed, together with one of a head-shaped unit, in a position substantially corresponding to a human ear.

22. The system of claim 1, wherein the individual transfer function includes a cross-talk cancellation feature to reduce a feedback effect of the canceling sound detected by the source microphone.

23. A method of sound cancellation comprising:

detecting a sound input at an input location that is spatially remote from a sound source, the sound input including undesirable sound propagating from a mobile sound source remote from the input location;

determining a current location of the mobile sound source;

determining a current location of a mobile cancellation space;

providing a situational transfer function of a plurality of individual situational transfer functions, each individual transfer function corresponding to at least a sound source location and a cancellation space location;

identifying a current individual transfer function corresponding to the current location of the sound source and the current location of the cancellation space; and

broadcasting a cancellation sound based on the sound input and the current individual transfer function of the situational transfer function for reducing sound proximate the cancellation location, wherein the situational transfer function includes a situational transfer matrix function, W, W=1/(d−

e′

e) wherein e is a transfer function for sound propagation from the sound source to the source microphone, e is a transfer function for sound propagation from the speaker to the cancellation location, and d is a transfer function for sound propagation from the source microphone to the speaker, and the * operator denotes mathematical convolution.

24. The method of claim 23, further comprising training an algorithm to provide the situational transfer function.

25. The method of claim 24, wherein the training algorithm comprises the steps of:

detecting a first sound at a first location;

detecting a modified second sound at a second location, the modified second sound being a result of sound propagating from the first location to the second location; and

determining the situational transfer function, the situational transfer function approximating the second modified sound from the first sound.

26. The method of claim 25, further comprising obtaining a second signal using a training system comprising at least one microphone, the training system being at least one of:

head-wearable device and positionable at desired location of cancellation.

27. The method of claim 26, further comprising providing a training device comprising a head surrogate comprising a three dimensional object and at least one microphone.

28. The method of claim 23, further comprising analyzing the sound input for medical screening purposes.

29. The method of claim 23, wherein providing a situational transfer function of individual transfer functions comprises:

detecting first sound at a first location;

detecting a modified second sound at a second location, the modified second sound being a result of sound propagating to the second location;

determining an adaptive filtering function substantially removed of cross talk to provide a cancelling sound for cancelling the second sound;

halting detecting of the modified sound; and

determining a cancellation signal proximate the second location from the first sound and the adaptive filtering function.

30. The method of claim 23, wherein providing a situational transfer function of individual transfer functions comprises:

detecting a first sound at a first location;

detecting a modified second sound at a second location, the modified second sound being a result of sound propagating to the second location; and

determining an individual transfer function of the plurality of individual transfer functions based on the first and second location, the individual transfer function approximating the second modified sound from the first sound without requiring additional sound detecting at the second location.

31. The method of claim 23, further comprising:

analyzing a sound input to determine if a change in respiratory sounds occurs sufficient to identify a health condition comprising at least one of;

sleep apnea, pulmonary congestion, pulmonary edema, asthma, halted breathing, abnormal breathing, arousal, and disturbed sleep.

32. The method of claim 23, wherein broadcasting a cancellation sound further comprises:

transmitting a canceling signal from a parametric speaker that locally cancels the sound with respect to a cancellation location.

33. The method of claim 32, wherein transmitting a canceling signal further comprises transmitting a plurality of ultrasonic signals wherein the canceling signal is formed from the interaction of the plurality of ultrasonic signals.

34. The method of claim 32, wherein the canceling signal is formed from a nonlinear interaction of an ultrasonic signal with air.

35. The method in claim 32 wherein the canceling signal is formed from an interaction between a plurality of ultrasonic signals that creates a difference signal among the ultrasonic signals at the cancellation location.

36. The method in claim 32 wherein the ultrasonic signal comprises a carrier frequency component and a modulation component and nonlinear interaction between the carrier frequency component and the modulation component in air creates a cancellation sound by demodulation of the ultrasonic signal that is in a generally audible frequency range along the propagation path of the ultrasonic signal.

37. The method of claim 23, wherein the situational transfer function is determined using convolution of the individual transfer functions, and each of the individual transfer functions is configured to characterize propagation of sound with respect to a pair of spaced apart transducer.

38. The method of claim 23, wherein the situational transfer function is provided by a mathematical convolution of the plurality of individual transfer functions.

39. The method of claim 23, wherein the individual transfer functions are representative of at least one sound propagation path comprising:

from the sound source to at least one sound source microphone, from the sound source to at least one training microphone, from at least one speaker to at least one training microphone, from at least one speaker to at least one cancellation location, and/or from at least one speaker to at least one sound source microphone being representative of cross talk.

40. The method of claim 25 wherein the training algorithm is provided by determining and mathematically convolving individual transfer functions representing the plurality of sound propagation paths among the source location, the cancellation location, the microphones and the speakers.

41. The method of claim 23, wherein each individual transfer function is representative of the locations of a snorer and bed partner ears and is used selectively to generate a cancellation representative of the locations of the snorer and bed partner ears.