Method and system for obtaining an audio signal

• US 9,113,243 B2
• Filed: 08/16/2012
• Issued: 08/18/2015
• Est. Priority Date: 08/16/2012
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Nielsen, Johan Ludvig, Enstad, Gisle Langen
• Primary Examiner(s): Sing, Simon
• Assistant Examiner(s): Zhao, Eugene
• Application Number:
  US13/587,514
• Publication Number:
  US 20140050332A1
• Time in Patent Office: 1,097 Days
• Field of Search: 381/17, 381/86, 381/92, 381/310, 700/94
• US Class Current: 1/1
• CPC Class Codes: H04R 1/08 Mouthpieces; Microphones; Attachments therefor
• CPC Class Codes: H04R 1/20 Arrangements for obtaining desired frequency or directional characteristics for stereophonic purpose H04R5/00
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2430/23 Direction finding using a sum-delay beam-former
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

A method and system for obtaining an audio signal. In one embodiment, the method comprises receiving a first sound signal at a first microphone arranged at a first height vertically above a substantially flat surface; receiving a second sound signal at a second microphone arranged at a second height vertically above the substantially flat surface; processing a signal provided by the first microphone using a low pass filter; processing a signal provided by the second microphone using a high pass filter; adding the signals processed by the low pass filter and the high pass filter to form a sum signal; and outputting the sum signal as an audio signal.

Claims

1. A method comprising:

receiving a first sound signal at a first microphone arranged at a first height vertically above a flat surface;

receiving a second sound signal at a second microphone arranged at a second height vertically above the flat surface;

receiving a third sound signal at a third microphone arranged at the second height vertically above the flat surface, wherein the third microphone has a toroid characteristic;

processing a signal provided by the first microphone using a low pass filter;

processing a signal provided by the second microphone using a high pass filter;

processing a signal provided by the third microphone by a band pass filter;

adding the signals processed by the low pass filter, the band pass filter, and the high pass filter to form a sum signal; and

outputting the sum signal as an audio signal.

2. The method according to claim 1, further comprising:

receiving a third sound signal at a third microphone arranged at the second height vertically above the flat surface;

processing a signal provided by the third microphone by a band pass filter; and

adding the signal processed by the band pass filter to the signals processed by the low pass filter and the high pass filter to form the sum signal.

3. The method according to claim 2, wherein the third microphone is a toroid microphone.

4. The method according to claim 2, wherein:

the third microphone includes a plurality of microphone elements whose outputs are connected to a toroid processing module, and

an output signal of the toroid processing module forms the signal provided by the third microphone.

5. The method according to claim 1, wherein the first height is in a range of 0 mm to 40 mm.

6. The method according to claim 1, wherein the first height is in a range of 0 mm to 20 mm.

7. The method according to claim 1, wherein the second height is in a range of 10 cm to 50 cm.

8. The method according to claim 1, wherein the second height is in a range of 25 cm to 35 cm.

9. The method according to claim 1, wherein the low pass filter and the high pass filter each have a cutoff frequency in a range of 0.5 kHz to 3.0 kHz.

10. The method according to claim 1, wherein the low pass filter and the high pass filter each have a cutoff frequency in a range of 1.0 kHz to 1.5 kHz.

11. A system comprising:

a first microphone, which receives a first sound signal, arranged at a first height vertically above a flat surface;

a second microphone, which receives a second sound signal, arranged at a second height vertically above the flat surface;

a third microphone, which receives a third sound signal, arranged at the second height above the flat surface, wherein the third microphone is a toroid microphone;

a low pass filter configured to process a signal provided by the first microphone;

a bandpass filter configured to process a signal provided by the third microphone;

a high pass filter configured to process a signal provided by the second microphone; and

an adder configured to add an output signal provided by the low pass filter, an output signal provided by the band pass filter, and an output signal provided by the high pass filter to form a sum signal output as an audio signal.

12. The system according to claim 11, wherein

the third microphone includes a plurality of microphone elements whose outputs are connected to a toroid processing module, and

an output signal of the toroid processing module forms the signal provided to the band pass filter by the third microphone.

13. The system according to claim 11, wherein the first height is in a range of 0 mm to 40 mm.

14. The system according to claim 11, wherein the first height is in a range of 0 mm to 20 mm.

15. The system according to claim 11, wherein the second height is in a range of 10 cm to 50 cm.

16. The system according to claim 11, wherein the second height is in a range of 25 cm to 35 cm.

17. The system according to claim 11, wherein the low pass filter and the high pass filter each have a cutoff frequency in a range of 0.5 kHz to 3.0 kHz.

18. The system according to claim 11, wherein the low pass filter and the high pass filter each have a cutoff frequency in a range of 1.0 kHz to 1.5 kHz.