Anti-sound beam method and apparatus

• US 6,434,239 B1
• Filed: 10/03/1997
• Issued: 08/13/2002
• Est. Priority Date: 10/03/1997
• Status: Expired due to Fees

• Current Assignee: Michael J. Deluca
• Original Assignee: Michael J. Deluca
• Inventors: DeLuca, Michael Joseph
• Primary Examiner(s): Mei, Xu
• Application Number:
  US08/943,899
• Time in Patent Office: 1,775 Days
• Field of Search: 381/71.1, 381/71.9, 381/71.3, 381/71.14, 381/77, 381/72, 381/94.1, 381/94.9
• US Class Current: 381/71.2
• CPC Class Codes: G10K 11/1785 Methods, e.g. algorithms; Devices G10K11/1781, G10K11/1783 take precedence
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 11/17875 using an error signal without a reference signal, e.g. pure feedback
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/128 Vehicles
• CPC Class Codes: G10K 2210/3026 Feedback
• CPC Class Codes: G10K 2210/3212 Actuator details, e.g. composition or microstructure
• CPC Class Codes: G10K 2210/3215 Arrays, e.g. for beamforming
• CPC Class Codes: G10K 2210/3216 Cancellation means disposed in the vicinity of the source
• CPC Class Codes: G10K 2210/3219 Geometry of the configuration
• CPC Class Codes: G10K 2210/511 Narrow band, e.g. implementations for single frequency cancellation

Abstract

A device generates a directional anti-sound beam by modulating an ultrasonic carrier with a sound canceling signal and exciting an ultrasonic transducer with the modulated signal. When the anti-sound beam is directed at a sound source, the level of sound from the sound source is reduced. A microphone monitors the resultant sound for adjusting the sound canceling signal. An alternate signal may be further modulated upon the anti-sound beam to provide a substitute sound at the sound source.

Claims

1. A method of at least partially canceling sound produced by an audio source comprising the steps of:

generating a sound canceling signal in response to the audio source;

modulating an ultrasonic carrier signal with the sound canceling signal to produce a modulated carrier signal;

exciting a transducer with the modulated carrier signal to produce a substantially directional anti-sound beam; and

directing the anti-sound beam towards the audio source.

2. The method according to claim 1 wherein said of directing the anti-sound beam towards the audio source at least partially cancels sound produced by the sound audio substantially at the sound source.

3. The method according to claim 1 wherein said step of modulating includes the step of amplitude modulating the ultrasonic carrier signal with the sound canceling signal.

4. The method according to claim 1 wherein the transducer has a frequency response substantially within the ultrasonic frequency range.

5. The method according to claim 1 wherein said step of generating further comprises the steps of:

monitoring the audio source; and

adjusting a characteristic of the sound canceling signal in response thereto.

6. The method according to claim 1 further comprising the steps of:

generating an alternate sound signal;

combining the alternate sound signal with the sound canceling signal to generate a combined signal;

wherein

said step of modulating modulates the ultrasonic carrier signal with the combined signal.

7. The method according to claim 6 further comprising the steps of:

monitoring sound substantially from the audio source to produce a monitored signal;

subtracting from the monitored signal a sound signal indicative of the alternate sound signal to produce a resultant signal, wherein said step of generating the sound canceling signal further comprises the step of;

adjusting a characteristic of the sound canceling signal in response the resultant signal.

8. The method according to claim 6 wherein said step of exciting produces a substantially directional anti-sound beam, and the method further comprises the step of directing the anti-sound beam towards the noise source.

9. A method of reducing sound comprising the steps of:

adding a sound canceling signal modulated upon an ultrasonic carrier with a sound signal to reduce the sound pressure level of the sound signal wherein the sound canceling signal modulated upon the ultrasonic carrier has a substantially directional characteristic and the sound signal is generated by a sound source; and

sound, directing the sound canceling signal modulated upon the ultrasonic carrier towards the sound source.

10. The method according to claim 9 wherein

said step of directing the sound canceling signal modulated upon the ultrasonic carrier towards the sound source reduces the sound pressure level by canceling sound produced by the sound source substantially at the sound source.

11. The method according to claim 9 wherein the sound canceling signal modulated upon the ultrasonic carrier has a substantially directional characteristic and the sound signal is present within a predetermined space, and the method further comprises the step of

directing the sound canceling signal modulated upon the ultrasonic carrier into the predetermined space in order to reduce the sound pressure level of the sound within the predetermined space.

12. The method according to claim 9 further comprising the steps of:

monitoring the resultant of said step of adding; and

adjusting ad characteristic of the sound canceling signal in response thereto.

13. The method according to claim 9 further wherein said step of adding further comprises the steps of:

combining with the sound canceling signal with an alternate sound signal to produce a combined signal; and

modulating the ultrasonic carrier with the combined signal wherein said step of adding both reduces the sound pressure level of the sound signal while producing a sound pressure level indicative of the alternate audio signal.

14. The method according to claim 13 wherein the combined signal modulated upon the ultrasonic carrier has a substantially directional characteristic and the sound signal is generated by a sound source, and the method further comprises the step of

directing the combined signal modulated upon the ultrasonic carrier towards the sound source.

15. A device for reducing sound comprising:

a sound canceling generator for generating a sound canceling signal in response to a sound source;

an ultrasonic carrier generator for generating an ultrasonic carrier signal;

a combiner for producing a combined signal by combining the sound canceling signal with the ultrasonic carrier signal; and

a transducer for producing a substantially directional anti-sound beam in response to the combined signal, whereby sound from the sound source is reduced by directing the anti-sound beam towards the sound source.

16. The device according to claims 15 wherein said combiner further comprises an amplitude modulator for amplitude modulating the ultrasonic carrier signal with the sound canceling signal.

17. The device according to claim 15 wherein said transducer is an ultrasonic transducer.

18. The device according to claim 15 further comprising:

a microphone coupled to said sound canceling generator and responsive to sound from the sound source combined with the anti-sound beam for generating a monitored signal, wherein said sound canceling generator produces the sound canceling signal in response to the monitored signal.

19. The device according to claim 15 further comprising:

an alternate sound generator for generating an alternate sound signal; and

an adder coupled to said sound canceling generator, said alternate sound generator and said combiner for adding the alternate sound signal with the sound canceling signal, thereby including the alternate sound signal within the combined signal.

20. The device, according to claim 19 further comprising:

a microphone responsive to sound from the sound source combined with the anti-sound beam for generating a monitored signal; and

a subtracter for substantially subtracting the alternate sound signal from the monitored signal to produce a difference signal, wherein said sound canceling generator produces the sound canceling signal in response to the difference signal.