LOW NOISE MICROPHONE FOR USE IN WINDY ENVIRONMENTS AND/OR IN THE PRESENCE OF ENGINE NOISE

• US 20080212819A1
• Filed: 08/28/2007
• Published: 09/04/2008
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: Cerwin, Stephen Anthony, Dennis, Martin Gray
• Granted Patent: US 8,116,482 B2
• Time in Patent Office: Days
• US Class Current: 381/359
• CPC Class Codes: H04R 1/086 Protective screens, e.g. all weather or wind screens
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers

Abstract

A microphone for use in windy environments. The microphone uses a transducer to flood the environment outside the microphone with a high frequency (such as an ultrasonic) acoustic field. The sounds desired to be detected are mixed with the high frequency carrier, and can then be received by the microphone with less wind noise. The microphone then demodulates the desired sound signals from the high frequency carrier. The microphone can be configured in a special emitter-receiver configuration that also reduces interference from engine noise.

Claims

1. A microphone for detecting sound and for reducing wind noise that interferes with the sound, comprising:

microphone circuitry for detecting the desired sounds;

wherein the microphone circuitry comprises at least one transducer for generating a high frequency acoustic field, such that the high frequency acoustic field is mixed with the sound, thereby providing a mixed signal having a high frequency acoustic carrier and the sound as sideband signals, and at least one reflector positioned relative to the emitter such that it reflects the high frequency acoustic field back to the transducer.

2. The microphone of claim 1, wherein the high frequency is an ultrasonic frequency.

3. The microphone of claim 1, wherein the transducer and reflector are spaced to reinforce a standing wave between them.

4. The microphone of claim 1, wherein the microphone circuitry has a circular array of transducers and reflectors.

5. The microphone of claim 1, further comprising a demodulator for receiving the mixed signal from the transducer and for extracting the desired sound signal from the mixed signal.

6. A microphone for detecting sound and for reducing wind noise that interferes with the sound, comprising:

microphone circuitry for detecting the desired sounds;

wherein the microphone circuitry comprises at least one emitter for generating a high frequency acoustic field, such that the high frequency acoustic field is mixed with the sound, thereby providing a mixed signal having a high frequency acoustic carrier and the sound as sideband signals, and at least one receiver positioned relative to the emitter such that it receives the mixed signal.

7. The microphone of claim 6, wherein the high frequency is an ultrasonic frequency.

8. The microphone of claim 6, wherein the transducers are spaced to reinforce a standing wave between them.

9. The microphone of claim 6, wherein the microphone circuitry has a circular array of transducers.

10. The microphone of claim 6, wherein each emitter and each receiver is an emitter-receiver transducer.

11. The microphone of claim 6, further comprising a demodulator for extracting the desired sound signal from the mixed signal.

12. A microphone array for detecting sound and for reducing wind noise that interferes with the sound, comprising:

microphone circuitry for detecting the desired sounds;

wherein the microphone circuitry comprises a number of emitters for generating a high frequency acoustic field, such that the high frequency acoustic field is mixed with the sound, thereby providing a mixed signal having a high frequency acoustic carrier and the sound as sideband signals, and a number of receivers positioned relative to the emitters such that they receive the mixed signal;

wherein the emitters and receivers are arranged in an annular geometry, such that the emitters and receivers are in orthogonal pairs.

13. The microphone of claim 12, wherein the high frequency is an ultrasonic frequency.

14. A microphone array for detecting sound and for reducing wind noise that interferes with the sound, comprising:

microphone circuitry for detecting the desired sounds;

wherein the microphone circuitry comprises a central emitter for radially generating a high frequency acoustic field, such that the high frequency acoustic field is mixed with the sound, thereby providing a mixed signal having a high frequency acoustic carrier and the sound as sideband signals, and a number of receivers annularly positioned relative to the emitter such that they receive the mixed signal.

15. The microphone of claim 14, wherein the high frequency is an ultrasonic frequency.

16. The microphone of claim 14, wherein the emitter is not in the same plane as the receivers.

17. A method of detecting sound and for reducing wind noise that interferes with the sound, comprising:

using at least one acoustic emitter to generate a high frequency acoustic field, such that the high frequency acoustic field is mixed with the sound, thereby providing a mixed signal having a high frequency acoustic carrier and the sound as sideband signals; and

using at least one receiver positioned relative to the emitters such that they receive the mixed signal; and

demodulating the mixed signal to detect the sound.

18. The method of claim 17, wherein a number of emitters and receivers are arranged in an annular geometry.

19. The method of claim 17, wherein a radially emitting receiver centrally located relative to a number of annular receivers.

20. The method of claim 17, wherein the high frequency is an ultrasonic frequency.

21. The method of claim 17, wherein the microphone is mounted on equipment with an engine and further comprising the step of arranging the receivers such that at least one receivers has an acoustic path to the emitter that is not co-axial with noise from the engine.

22. The method of claim 17, wherein the microphone is housed in a windscreen, and the acoustic field is generated in front of the windscreen.