Apparatus for detecting direction of sound source and turning microphone toward sound source

• US 6,516,066 B2
• Filed: 03/29/2001
• Issued: 02/04/2003
• Est. Priority Date: 04/11/2000
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hayashi, Kensuke
• Primary Examiner(s): Harvey, Minsun Oh
• Application Number:
  US09/820,342
• Publication Number:
  US 20010028719A1
• Time in Patent Office: 677 Days
• Field of Search: 381/91, 381/92, 381/122, 348/14.08, 348/14.09, 348/14.1, 379/202.01
• US Class Current: 381/92
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

An object of the present invention is to turn microphones accurately and quickly toward a sound source. The first microphone pair is rotated by rotation means and driving means, so that the microphones are equidistant from a sound source. The sound picked up by the microphones is analyzed in a plurality of frequency ranges to obtain delay time components of the arrival of the sound wave. The delay time components are averaged with a prescribed coefficients so that the lower frequency components hardly affects the result of the direction detection. The averaged delay is converted into an angle of direction of the sound source. Thus, the microphones pair is directed in front of the sound source on the basis of the direction angle converted from the averaged delay time.

Claims

1. A microphone direction set-up apparatus for detecting a sound source and for turning a microphone pair toward said sound source, which comprises:

a rotatable pair of microphones for picking up sound wave from said sound source;

time difference calculation means for calculating a time difference between a time when said sound wave arrives at a microphone and a time when said sound wave arrives at another microphone in said rotatable pair;

rotation means for rotating said rotatable pair on the basis of said time difference,

wherein said time difference is an average of time differences in a plurality of frequency ranges; and

said rotation means rotates on the basis of said average said rotatable pair toward said sound source so that said average tends to zero.

2. The microphone direction set-up apparatus according to claim 1, wherein:

said average is a summation of time differences in a plurality of frequency ranges multiplied by coefficients prescribed for each of said time differences in a plurality of frequency ranges frequency ranges;

a summation of all of said coefficients is unity; and

each of said coefficients decreases as each of said frequency ranges becomes lower.

3. The microphone direction set-up apparatus according to claim 1, which further comprises image pick-up means for picking up an image of an object of said sound source.

4. The microphone direction set-up apparatus according to claim 1, which further comprises:

a fixed pair of microphones for picking up sound wave from said sound source;

time difference calculation means for calculating a time difference between a time when said sound wave arrives at a microphone and a time when said sound wave arrives at another microphone in said fixed pair;

conversion means for converting said time difference into an angle directed to said sound source,

wherein;

said time difference is an average of time differences in a plurality of frequency ranges; and

said rotation means turns said rotatable pair to a direction defined by said angle.

5. The microphone direction set-up apparatus according to claim 4, wherein:

said average is the summation of said frequency components of said time difference multiplied by coefficients prescribed for each of said frequency range;

a summation of all of said coefficients is unity; and

each of said coefficients decreases as said frequency range becomes lower.

6. The microphone direction set-up apparatus according to claim 4, wherein said fixed pair of microphones are directed toward the substantial center of a plurality of sound sources.