Adaptive personal active noise reduction system

• US 7,110,551 B1
• Filed: 03/27/2000
• Issued: 09/19/2006
• Est. Priority Date: 05/06/1997
• Status: Expired due to Fees

• Current Assignee: Gentex Corporation
• Original Assignee: Adaptive Technologies, Inc.
• Inventors: Saunders, William Richard, Vaudrey, Michael Allen
• Primary Examiner(s): Mei, Xu
• Application Number:
  US09/534,730
• Time in Patent Office: 2,367 Days
• Field of Search: 381/71.6, 381/71.7, 381/72, 381/74, 381/73.1, 381/370, 381/371, 381/378, 381/384, 381/94.2, 381/94.3
• US Class Current: 381/71.6
• 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 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 2210/10 Applications
• CPC Class Codes: G10K 2210/101 One dimensional
• CPC Class Codes: G10K 2210/108 Communication systems, e.g. where useful sound is kept and noise is cancelled
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/1082 Microphones, e.g. systems using "virtual" microphones
• CPC Class Codes: G10K 2210/128 Vehicles
• CPC Class Codes: G10K 2210/1282 Automobiles
• CPC Class Codes: G10K 2210/3016 Control strategies, e.g. energy minimization or intensity measurements
• CPC Class Codes: G10K 2210/3025 Determination of spectrum characteristics, e.g. FFT
• CPC Class Codes: G10K 2210/3026 Feedback
• CPC Class Codes: G10K 2210/3027 Feedforward
• CPC Class Codes: G10K 2210/3031 Hardware, e.g. architecture
• CPC Class Codes: G10K 2210/3033 Information contained in memory, e.g. stored signals or transfer functions
• CPC Class Codes: G10K 2210/30351 Identification of the environment for applying appropriate model characteristics
• CPC Class Codes: G10K 2210/3042 Parallel processing
• CPC Class Codes: G10K 2210/3046 Multiple acoustic inputs, multiple acoustic outputs
• CPC Class Codes: G10K 2210/3056 Variable gain
• CPC Class Codes: G10K 2210/3214 : Architectures, e.g. special constructional features or arrangements of features
• CPC Class Codes: G10K 2210/3217 : Collocated sensor and cancelling actuator, e.g. "virtual earth" designs
• CPC Class Codes: G10K 2210/3219 : Geometry of the configuration
• CPC Class Codes: G10K 2210/3221 : Headrests, seats or the like, for personal ANC systems
• CPC Class Codes: G10K 2210/3222 : Manual tuning
• CPC Class Codes: G10K 2210/506 : Feedback, e.g. howling
• CPC Class Codes: G10K 2210/511 : Narrow band, e.g. implementations for single frequency cancellation
• CPC Class Codes: H04R 1/1083 : Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06

Abstract

An improved active noise reduction system which has a transducer, an electro-acoustic sensing means including adjacent to the transducer, an attenuation means with electro-acoustic sensing means to attenuate selected sound frequencies, said system utilizing both feed forward control means and feedback control means comprising a heteronomous electronic controller with algorithmic transfer function and said controller being individually operable.

Claims

1. A personal active noise attenuating system comprising:

a heteronomous electronic controller and a control actuator comprising a radius of reverberation;

a first and second electro-acoustic transducer mounted on opposite sides of a head support structure;

a first actuator located adjacent to the first electro-acoustic transducer and a second actuator located adjacent to the second transducer, wherein the first and second electro-acoustic transducers define a zone of reverberation on each side of the support structure adjacent a wearer'"'"'s ears, wherein the first and second electro-acoustic transducers are each adapted to be movable within said zones so as to provide an unchanging-transfer function estimate for a filtered reference which does not need to be updated, and whereby a transfer function is identified for all frequencies within the control bandwidth and thus is specified independent of the nature of the disturbance signal;

an adaptive feedforward component utilizing the transfer function estimate for the heteronomous electronic controller which is adapted to attenuate tonal noises, and a feedback component of the heteronomous electronic controller which is adapted to attenuate broadband noises; and

a linear combiner adapted for summing a linear combination of the adaptive feedward component and the feedback component so as to generate a heteronomous control signal.

2. The system as in claim 1, wherein the first electro-acoustic transducer comprises a first adjuster, and wherein the second electro-acoustic transducer comprises a second adjuster, and wherein the first and second adjusters are adapted to move the first and second electro-acoustic transducers within a range relative to the first and second actuators, and wherein the transfer function remains virtually unchanged.

3. The system as in claim 2 wherein the first and second adjusters comprise a geared system to move the first and second electro-acoustic transducers.

4. The system as in claim 3 wherein the geared system is manually adjustable.

5. The system as in claim 3 wherein the geared system is powered by a motor adapted to move the geared system in response to a signal from the feedback component.

6. The system as in claim 1 wherein the first and second electro-acoustic transducers comprise a motorized adjuster adapted to calculate an optimal position of the first and second electro-acoustic transducers with respect to the noise field and to adjust a current position of the first and second transducers so as to optimize a perceived noise reduction and field of silence dimension in response to a signal from the feedback component.

7. The system as in claim 1 wherein the adaptive feedforward component and the feedback component are linked to the first electro-acoustic transducer and the first actuator and to the second electro-acoustic transducer and the second actuator so as to minimize feedback and instabilities in the heteronomous control system.

8. The system as in claim 1 wherein the feedback component provides feedback control to transfer function by sound pressure.

9. The system as in claim 1 wherein an electro-acoustic output signal provides for rejection of a disturbance noise while minimizing sensitivity of the feedback component.

10. The system as in claim 2 wherein the transfer function is for a leaky LMS algorithm.