Microphone modeling system and method

• US 8,666,090 B1
• Filed: 10/25/2013
• Issued: 03/04/2014
• Est. Priority Date: 02/26/2013
• Status: Active Grant

• Current Assignee: Universal Audio, Inc.
• Original Assignee: Full Code Audio LLC
• Inventors: Townsend, Chris
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): FAHNERT, FRIEDRICH
• Application Number:
  US14/064,034
• Time in Patent Office: 130 Days
• Field of Search: 381/58, 381/61, 381/91, 381/92, 381/97, 381/98, 381/99, 381/103, 381/111, 381/112, 381/113, 381/114, 381/115
• US Class Current: 381/92
• CPC Class Codes: H04R 1/04 Structural association of microphone with electric circuitry therefor in deaf-aid sets H04R25/00
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2201/403 Linear arrays of transducers
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Disclosed is a system and method with independent adjustment of on and off-axis tonality and a system and method for modeling an idealized off-axis polar response of a directional microphone. The system can include two or more microphone capsules arranged in close proximity within a single housing and a filtering algorithm applied to the output of each microphone capsule that results in a signal that has a predominantly idealized on and off-axis user selectable polar pattern responses and user selectable microphone modeling which models the on-axis frequency response of a physical or virtual microphone. Optionally, the system and method can compensate for the on and off-axis polar response changes due to low-frequency proximity-effect.

Claims

1. A method for producing user selectable on-axis microphone models combined with idealized polar responses, including:

creating a user selected idealized on-axis and off-axis polar response from a plurality of microphone capsule signals;

emulating a user selected on-axis microphone model frequency response; and

adjusting the user selected idealized on-axis and off-axis polar response substantially independent from the user selected on-axis microphone model frequency response.

2. The method of claim 1, further including:

emulating the user selected on-axis microphone model frequency response is carried out by an on-axis microphone model filter; and

applying a set of microphone model type coefficients to the on-axis microphone model filter.

3. The method of claim 2, wherein:

creating the user selected idealized on-axis and off axis polar response from the plurality of microphone capsule signals is carried out by a plurality of corresponding beamforming filter.

4. The method of claim 1 further including:

producing the user selected idealized on-axis and off-axis polar response from the plurality of microphone capsule signals and emulating the user selected on-axis microphone model frequency response are carried out by a plurality of beamforming filters; and

applying a set of coefficients to the plurality of beamforming filters that model a user selected combination of the user selected idealized on-axis and off-axis polar response and the user selected on-axis microphone model frequency response.

5. The method of claim 1, further including:

compensating for a proximity-effect due to the plurality of microphone capsule signals.

6. The method of claim 5 wherein compensating for the proximity-effect due to the plurality of microphone capsule signals is carried out by convolving a plurality of beamforming filters with a high frequency on-axis model filter and a sum of a high frequency and a low frequency crossover filter.

7. The method of claim 5, further including:

creating a high frequency component of the user selected idealized on-axis and off-axis polar response;

creating a low frequency component of the user selected on-axis microphone model frequency response; and

applying a microphone model filter to the high frequency component.

8. The method of claim 1, further including:

applying a proximity filter is applied to a first order gradient component of a linear combination of the plurality of microphone capsule signals.

9. The method of claim 8, further including:

applying a second order proximity filter to a second order gradient component of the linear combination of the plurality of microphone capsule signals.

10. The method of claim 1, further including:

emulating a user selected angle of rotation frequency response with respect to an axis position of a modeled microphone.

11. A microphone, including:

a plurality of microphone capsules; and

a processor for receiving and acting on a plurality of microphone capsule signals, the processor configured to;

(a) produce an idealized on-axis and off-polar pattern response based on a user-selected polar pattern type, and

(b) emulate a user selected on-axis microphone model frequency response; and

(c) adjust the idealized on-axis and off-axis polar response substantially independent from the user selected on-axis microphone model frequency response.

12. The microphone of claim 11, wherein the user-selected polar pattern type and a user selected on-axis microphone model are selected externally from the microphone.

13. The microphone of claim 11, wherein the processor is further configured to adjust a microphone model frequency response to simulate rotation of the microphone with respect to a sound source based on a simulated microphone rotation angle selected by a user.

14. The microphone of claim 11, further including:

the processor is further configured to compensate for a microphone proximity-effect based on a user estimated distance selection.

15. The microphone of claim 11, wherein:

the processor is further configured to compensate for an off-axis microphone proximity-effect based on a user selection of estimated off-axis distance and compensate for an on-axis proximity-effect based on a user selection of estimated on-axis distance.

16. The microphone of claim 11, wherein, the processor is further configured to:

produce the idealized on-axis and off-axis polar pattern response based on the user-selected polar pattern type with a plurality of beamforming filters; and

emulate the user selected on-axis microphone model frequency response with an on-axis microphone modeling filter.

17. A system for producing user selectable on-axis microphone models combined with idealized polar responses, including:

a polar pattern user control for selecting a polar pattern;

a microphone model type user control for selecting a microphone model; and

a processor for receiving and acting on a plurality of microphone capsule signals, the processor configured to;

(a) produce an idealized on-axis and off-axis polar pattern response based on a user-selected polar pattern type from the polar pattern user control, and

(b) emulates a user selected on-axis microphone model frequency response based on the microphone model selected from the microphone model type user control; and

(c) adjust the idealized on-axis and off-axis polar response substantially independent from the user selected on-axis microphone model frequency response.

18. The system of claim 17, further including:

a graphical user interface; and

the polar pattern user control and the microphone model type user control are virtual controls on the graphical user interface.

19. The system of claim 17, further including:

a user microphone model axis control; and

the processor further configured to adjust a microphone model frequency response to simulate rotation of a modeled microphone with respect to a sound source based on a user selection of the user microphone model axis control.

20. The system of claim 17, further including:

a user microphone model physical axis control;

a user microphone model virtual axis control; and

the processor further configured to adjust a microphone model frequency response to simulate rotation of a modeled microphone with respect to a sound source based on a user selection of the user microphone model virtual axis control and the user microphone model physical axis control.

21. The system of claim 17, further including:

a user distance control; and

the processor is further configured to compensate for a microphone proximity-effect based on a user selection from the user distance control.

22. The system of claim 21, wherein:

the user distance control is an on-axis distance control and an off-axis distance control; and

the processor is further configured to compensate for an off-axis microphone proximity-effect based on a user selection from the off-axis distance control and reducing an on-axis proximity-effect based on the on-axis distance control.

23. The system of claim 17, wherein, the processor is further configured to:

produce the idealized on-axis and off-polar pattern response based on the user-selected polar pattern type with a plurality of beamforming filters; and

emulate the user selected on-axis microphone model frequency response with a microphone modeling filter.

24. The system of claim 17, wherein the processor is further configured to:

produce the idealized on-axis and off-axis polar response from the plurality of microphone capsule signals and emulate the user selected on-axis microphone model frequency response by a plurality of beamforming filters; and

apply a set of coefficients to the plurality of beamforming filters that model a user selected combination of the idealized on-axis and off-axis polar response and the user selected on-axis microphone model frequency response.