Microphone apparatus

• US 5,471,538 A
• Filed: 05/07/1993
• Issued: 11/28/1995
• Est. Priority Date: 05/08/1992
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Gyotoku, Kaoru, Sasaki, Tooru
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US08/057,821
• Time in Patent Office: 935 Days
• Field of Search: 381/92, 381/94
• 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

A microphone apparatus having a first microphone for picking up a desired sound and a second microphone with directionality in which sensitivity is low to the desired sound arrival direction. A sound signal from the second microphone is supplied to a subtracting circuit through an adaptive filter. The subtracting circuit subtracts an output signal of the adaptive filter from the sound signal coming from the first microphone. A circuit is provided to adjust the adaptive filter so that the output power of the subtracting circuit is minimized. The setup implements a microphone system which is compact in size and easily provides desired directionality.

Claims

1. A microphone apparatus comprising:

a first microphone for picking up at least a desired sound coming from an arrival direction;

a second microphone arranged in proximity to said adjacent said first microphone and having a directionality in which said second microphone has a low sound-pickup sensitivity in said arrival direction of said desired sound, wherein said second microphone comprises a plurality of non-directional microphone units axially aligned and placed in proximity to each other so as to be spaced apart by a predetermined distance, a filter receiving an output from one of said plurality of microphone units and wherein output sound signals of remaining ones of said plurality of nondirectional microphone units and an output of said filter are combined to provide an output representing a directional microphone;

adaptive filter means to which said output from said second microphone is supplied; and

subtracting means for subtracting an output of said adaptive filter means from a signal picked up by said first microphone for producing an output signal of said microphone apparatus;

wherein said adaptive filter means is adjusted in response to the output signal of said subtracting means to minimize a power of the output signal of said subtracting means.

2. A microphone apparatus as defined in claim 1, wherein said adaptive filter means controls a filter weight to minimize the power of the output signal of said subtracting means.

3. A microphone apparatus comprising:

a first microphone having a first directionality;

a second microphone arranged in proximity to said first microphone and having a second directionality different than said first directionality of said first microphone, wherein said second microphone comprises a plurality of non-directional microphone units axially aligned and placed in proximity to each other so as to be spaced apart by a predetermined distance, a filter receiving an output from one of said plurality of microphone units and wherein output sound signals of remaining ones of said plurality of non-directional microphone units and an output of said filter are combined to provide an output representing a directional microphone;

adaptive filter means to which said output from said second microphone is supplied; and

subtracting means for subtracting an output of said adaptive filter means from a signal picked up by said first microphone for producing an output signal of said microphone apparatus;

wherein said adaptive filter means is adjusted in response to the output signal of said subtracting means to minimize a power of the output signal of said subtracting means.

4. A microphone apparatus as defined in claim 3, wherein said adaptive filter means controls a filter weight to minimize the power of the output signal of said subtracting means.

5. A microphone apparatus used on a lightweight hand-held television camera with an incorporated video cassette recorder comprising:

a first microphone having a first directionality for picking up at least a sound arriving from a direction in which a lens of said television camera is directed;

a second microphone arranged proximate and adjacent said first microphone and having a second directionality different than said first directionality of said first microphone and having a low sensitivity to a sound arriving from said direction, wherein said second microphone comprises a plurality of non-directional microphone units axially aligned and placed in proximity to each other so as to be spaced apart by a predetermined distance, a filter receiving an output from one of said plurality of microphone units and wherein output sound signals of remaining ones of said plurality of nondirectional microphone units and an output of said filter are combined to provide an output representing a directional microphone;

adaptive filter means to which said output from said second microphone is supplied; and

subtracting means for subtracting an output of said adaptive filter means from a signal picked up by said first microphone for producing an output signal of said microphone apparatus;

wherein said adaptive filter means is adjusted by the output signal of said subtracting means to minimize a power of the output signal of said subtracting means.

6. A microphone apparatus as defined in claim 5, wherein said adaptive filter means controls a filter weight to minimize the power of the output signal of said subtracting means.