Vehicular microphone assembly using fractional power phase normalization

• US 8,081,772 B2
• Filed: 11/20/2008
• Issued: 12/20/2011
• Est. Priority Date: 11/20/2008
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Turnbull, Robert R., Watson, Alan R., Bryson, Michael A.
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US12/274,749
• Publication Number:
  US 20100124339A1
• Time in Patent Office: 1,125 Days
• Field of Search: 381/58, 381/66, 381/86, 381/312, 381/357, 381/359, 381/392, 455/345, 455/347, 455/566, 704/216, 704/226, 704/231, 704/E21.004
• US Class Current: 381/86
• CPC Class Codes: H04R 2410/01 Noise reduction using microphones having different directional characteristics
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A triangular microphone assembly (101) for use in a vehicle accessory includes a mirror housing (106) adapted for attachment to the interior of the vehicle. A mirror is disposed in an opening of the mirror housing (106) and a plurality of virtual digital microphones (108a, 108b, 108c) are arranged in a substantially triangular configuration in the mirror housing (106). A digital signal processor (DSP) (537) is used for receiving signals from the plurality of digital microphones (108a, 108b, 108c) such that the digital microphones exhibit directional characteristics for reducing undesirable noise in at least one direction by normalizing the phase of the received signals as a function of signal frequency.

Claims

1. A digital microphone system comprising:

a plurality of digital microphones each having a digital output signal;

a digital signal processor (DSP) for receiving each digital output signal and providing a processed digital output signal; and

wherein each of the plurality of digital microphones are phase normalized as a function of the audio frequency received at the digital microphones.

2. A digital microphone system as in claim 1, wherein the plurality of digital microphones operate as a delay-and-sum beam-former microphone array in connection with the DSP.

3. A digital microphone system as in claim 2, wherein the delay-and-sum beam-former microphone array utilizes parameterizing phase correction for orienting a beam center and beam width.

4. A digital microphone system as in claim 1, wherein the plurality of digital microphones utilize a gain smoothing time function having a plurality of attack and release constants for providing directional characteristics.

5. A digital microphone system as in claim 4, wherein the plurality of attack and release characteristics operate as a phase based gain adjustment.

6. A digital microphone system as in claim 1, wherein each of the plurality of digital microphones include a transducer, a preamplifier, and a sigma delta modulator.

7. A digital microphone system as in claim 1, wherein the DSP provides a de-emphasis of predetermined frequency bands without increasing the amplitude of unwanted frequency bands.

8. A vehicular audio signal processing system for use with electronic devices comprising:

a plurality of digital microphones providing a plurality of signals;

a digital signal processor (DSP) using at least one non-linear process for processing the plurality of signals; and

wherein the non-linear process provides phase correction as a function of frequency input into the plurality of digital microphones for accounting for non-ideal phase characteristics of the audio received at the plurality of digital microphones.

9. A vehicular audio signal processing system as in claim 8, wherein the DSP forms three directional patterns having common null locations for defining a unique spatial location.

10. A vehicular audio signal processing system as in claim 8, wherein the DSP forms three directional patterns having different central axes for defining a unique spatial location.

11. A vehicular audio signal processing system as in claim 8, wherein the DSP utilizes parameterizing phase correction for orienting a microphone beam center and microphone beam width.

12. A vehicular audio signal processing system as in claim 8, wherein the plurality of digital microphones operate as a delay-and-sum beam-former microphone array.

13. A vehicular audio signal processing system as in claim 8, wherein the plurality of digital microphones utilize a gain smoothing time function having a plurality of attack and release constants for providing directional characteristics.

14. A vehicular audio signal processing system as in claim 13, wherein the plurality of attack and release characteristics operate as a phase based gain adjustment.

15. A vehicular audio signal processing system as in claim 8, wherein the DSP provides a de-emphasis of predetermined frequency bands without increasing the amplitude of unwanted frequency bands.

16. A microphone assembly for use in a vehicle comprising:

a rearview mirror housing adapted for attachment to the interior of the vehicle, the rearview mirror housing having a back surface generally facing the front of the vehicle and an opening generally facing the rear of the vehicle;

a mirror disposed in the opening of the mirror housing;

a plurality of microphone transducers arranged in a substantially triangular configuration in the mirror housing to form a microphone array; and

wherein each of the plurality of digital microphones are phase normalized as a function of the audio frequency received at the digital microphones for use with a digital signal processor (DSP).

17. A microphone assembly as in claim 16, wherein the attack, release, gain, and beam width of the microphone array can be adjusted.

18. A microphone assembly as in claim 16, wherein the microphone array is formed into a triangular configuration.

19. A microphone assembly as in claim 16, wherein the plurality of microphone transducers utilize a gain smoothing time function having a plurality of attack and release constants for providing directional characteristics.

20. A microphone assembly as in claim 19, wherein the plurality of attack and release constants operate to provide a phase based gain adjustment.

21. A microphone assembly as in claim 16, wherein the DSP provides a de-emphasis of predetermined frequency bands without increasing the amplitude of unwanted frequency bands.

22. A triangular microphone assembly for use in a vehicle accessory comprising:

a mirror housing adapted for attachment to the interior of the vehicle;

a mirror disposed in an opening of the mirror housing;

a plurality of virtual digital microphones arranged in a substantially triangular configuration in the mirror housing;

a digital signal processor (DSP) for receiving signals from the plurality of digital microphones; and

wherein the digital microphones exhibit directional characteristics for reducing undesirable noise in at least one direction by normalizing the phase of the received signals as a function of signal frequency.

23. A triangular microphone assembly as in claim 22, the plurality of digital microphones each include a transducer, preamplifier, and delta sigma modulator.

24. A triangular microphone assembly as in claim 22, wherein the plurality of virtual digital microphones operate as a delay-and-sum beam-former microphone array.

25. A triangular microphone assembly as in claim 22, wherein the plurality of virtual microphone transducers utilize a gain smoothing time function having a plurality of attack and release constants for providing directional characteristics.

26. A triangular microphone assembly as in claim 25, wherein the plurality of attack and release characteristics operate as a phase based gain adjustment.

27. A triangular microphone assembly as in claim 22, wherein the DSP provides a de-emphasis of predetermined frequency bands without increasing the amplitude of unwanted frequency bands.