System and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources

• US 7,283,948 B2
• Filed: 06/07/2002
• Issued: 10/16/2007
• Est. Priority Date: 02/06/1996
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Ng, Lawrence C., Burnett, Greg C., Holzrichter, John F.
• Primary Examiner(s): MCFADDEN, SUSAN IRIS
• Application Number:
  US10/165,565
• Publication Number:
  US 20020198690A1
• Time in Patent Office: 1,957 Days
• Field of Search: 381/71.12, 703/2, 704/2
• US Class Current: 704/2
• CPC Class Codes: G01H 1/12 of longitudinal or not specified vibrations
• CPC Class Codes: G01H 3/00 Measuring characteristics of vibrations by using a detector in a fluid G01H7/00, G01H9/00, G01H11/00 take precedence
• CPC Class Codes: G01H 9/00 Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
• CPC Class Codes: G01N 2291/02491 Materials with nonlinear acoustic properties
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/02872 Pressure
• CPC Class Codes: G06F 18/256 of results relating to different input data, e.g. multimodal recognition
• CPC Class Codes: G06V 40/10 Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
• CPC Class Codes: G10K 11/16 Methods or devices for protecting against, or for damping, noise or other acoustic waves in general G10K11/36 takes precedence
• CPC Class Codes: G10L 15/02 Feature extraction for speech recognition; Selection of recognition unit
• CPC Class Codes: G10L 15/24 Speech recognition using non-acoustical features
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 21/0272 Voice signal separating

Abstract

A system and method for characterizing, synthesizing, and/or canceling out acoustic signals from inanimate sound sources is disclosed. Propagating wave electromagnetic sensors monitor excitation sources in sound producing systems, such as machines, musical instruments, and various other structures. Acoustical output from these sound producing systems is also monitored. From such information, a transfer function characterizing the sound producing system is generated. From the transfer function, acoustical output from the sound producing system may be synthesized or canceled. The methods disclosed enable accurate calculation of matched transfer functions relating specific excitations to specific acoustical outputs. Knowledge of such signals and functions can be used to effect various sound replication, sound source identification, and sound cancellation applications.

Claims

1. A method for canceling out acoustic signals from an inanimate sound source, comprising the steps of:

directly measuring an excitation function from excitations of the inanimate sound source;

directly measuring an acoustic function from acoustic emissions of the inanimate sound source;

calculating a transfer function from the excitation function and the acoustic function;

receiving cancellation instructions;

convolving the instant excitation function with the previously determined transfer function to synthesize a canceling acoustic signal; and

broadcasting the canceling acoustic signal proximate to the acoustic emissions.

2. The method of claim 1:

wherein the step of generating an excitation function further comprises the step of, instantly generating an excitation function from excitations of the inanimate sound source;

further comprising the step of;

storing the transfer function in memory and in a transfer function processor; and

wherein the step of convolving the excitation function further includes the step of, convolving the instantly generated excitation function with the transfer function stored in the memory to synthesize a canceling acoustic signal.

3. The method of claim 1 wherein the step of generating an acoustic function further comprises the step of:

locating an acoustic sensor as near to a predetermined sound cancellation point as possible.

4. The method of claim 1 wherein the step of generating an excitation function further comprises the step of:

selecting a default time frame based on a reverberation time of the inanimate sound source.

5. The method of claim 3 further comprising the step of:

performing an entire sequence of the generating, calculating, convolving, and broadcasting steps over a time period which is less than a time required for the acoustic emissions to reach a listener.

6. A system for canceling out acoustic signals from an inanimate sound source, comprising:

means for directly measuring an excitation function from excitations of the inanimate sound source;

means for directly measuring an acoustic function from acoustic emissions of the inanimate sound source;

means for calculating a transfer function from said previously measured excitation function and said previously measured acoustic function;

means for receiving cancellation instructions;

means for convolving the instant excitation function with the previously determined transfer function to synthesize a canceling acoustic signal; and

means for broadcasting the canceling acoustic signal proximate to the acoustic emissions.