Microphone array apparatus

• US 6,317,501 B1
• Filed: 03/16/1998
• Issued: 11/13/2001
• Est. Priority Date: 06/26/1997
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Matsuo, Naoshi
• Primary Examiner(s): Mei, Xu
• Application Number:
  US09/039,777
• Time in Patent Office: 1,338 Days
• Field of Search: 381/66, 381/71.1, 381/71.11, 381/71.12, 381/91, 381/92, 381/94.1, 381/94.2, 381/94.4, 381/122, 381/94.7, 381/94.5, 381/71.9, 381/FOR 123, 381/FOR 124, 379/406, 379/410, 379/411, 708/322
• US Class Current: 381/92
• CPC Class Codes: H04R 2201/403 Linear arrays of transducers
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• 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

Abstract

A microphone array apparatus includes a microphone array including microphones, one of the microphones being a reference microphone, filters receiving output signals of the microphones, and a filter coefficient calculator which receives the output signals of the microphones, a noise and a residual signal obtained by subtracting filtered output signals of the microphones other than the reference microphone from a filtered output signal of the reference microphone and which obtain filter coefficients of the filters in accordance with an evaluation function based on the residual signal.

Claims

1. A microphone array apparatus comprising:

a microphone array including microphones, one of the microphones being a reference microphone;

filters receiving output signals of the microphones; and

a filter coefficient calculator which receives the output signals of the microphones, a noise and a residual signal obtained by subtracting filtered output signals of those of the microphones other than the reference microphone from a filtered output signal of the reference microphone and which obtain filter coefficients of the filters in accordance with an evaluation function represented by power of the residual signal.

2. The microphone array apparatus as claimed in claim 1, further comprising:

delay units provided in front of the filters; and

a delay calculator which calculates amounts of delays of the delay units on the basis of a maximum value of a crosscorrelation function obtained by a sum-of-product operation on the output signals of the microphones.

3. The microphone array apparatus as claimed in claim 1, wherein the noise is a signal which drives a speaker.

4. The microphone array apparatus as claimed in claim 1, further comprising a supplementary microphone which outputs a signal from a noise source.

5. The microphone array apparatus as claimed in claim 1, wherein the filter coefficient calculator includes a cyclic type low-pass filter which applies a comparatively small weight to past values of an output of said cyclic type low-pass filter.