Sound pickup apparatus and method for picking up sound

Patent metadata

Field	Value
Publication number	US-2016353203-A1
Application number	US-201615236375-A
Country	US
Kind code	A1
Filing date	Aug 12, 2016
Priority date	Aug 30, 2013
Publication date	Dec 1, 2016
Grant date	—

Abstract

A sound pickup apparatus and method form a bidirectionality and a unidirectionality based on sound signals picked up by microphones arranged at vertices of a triangle. A target sound is extracted by performing a spectral subtraction operation and, with respect to each frequency, a ratio of amplitude spectra of beamformer outputs between outputs is calculated for each microphone array of a directionality forming unit. A mode or median of the calculated ratio of amplitude spectra is set as a correction coefficient which corrects power of beamformer outputs for each of the microphone arrays and a target area sound is extracted.

First claim

What is claimed is:

1 . A sound pickup apparatus comprising:
a plurality of microphone arrays each including three microphones disposed at vertexes of an isosceles right triangle or a regular triangle; a directionality forming unit configured to form directionality, for each of the microphone arrays, only in a forward direction of each of the microphone arrays with respect to a target area by use of beamformers, for each output from each of the microphone arrays, the directionality forming unit comprising:
a bidirectionality forming unit configured to form a bidirectionality having a dead angle in a target direction by use of a sound signal picked up by two microphones which are located to be horizontal with respect to the target direction, among three microphones disposed at vertexes of an isosceles right triangle;
a unidirectionality forming unit configured to form a unidirectionality having a dead angle in the target direction by use of a sound signal picked up by two microphones which are located in a same direction as the target direction, among the three microphones; and
a target sound extracting unit configured to extract a target sound by performing a spectral subtraction of all outputs from the bidirectionality forming unit and the unidirectionality forming unit from either one of sound signals picked up by the two microphones located to be horizontal with respect to the target direction or a signal obtained by averaged sound signals picked up by the two microphones;
a power correction coefficient calculating unit configured to calculate, with respect to each frequency, a ratio of amplitude spectra of beamformer outputs between outputs for each of the microphone arrays from the directionality forming unit and set a mode or a median of the calculated ratio of amplitude spectra as a correction coefficient which corrects power of beamformer outputs for each of the microphone arrays; and a target area sound extracting unit configured to extract a target area sound by performing the following processes in sequence:
correcting a beamformer output from each of the microphone arrays from the directionality forming unit by use of the correction coefficient calculated by the power correction coefficient calculating unit,
performing a spectral subtraction of the beamformer output from each of the microphone arrays, the beamformer output being obtained by the correction, to extract a non-target area sound which is present in the target area direction when seen from each of the microphone arrays, and
performing a spectral subtraction of the extracted non-target area sound from the beamformer output from each of the microphone arrays from the directionality forming unit.

2 . The sound pickup apparatus according to claim 1 , further comprising:
a spatial coordinate data holding unit configured to hold position information of the target area, each of the microphone arrays, and the microphones included in each of the microphone arrays; an area acquiring unit configured to acquire information related to selected one or more target areas; and an area switching unit configured to perform the following:
acquire, on the basis of information related to the one or more target areas from the area acquiring unit, the position information of the target area, each of the microphone arrays, and the microphones included in each of the microphone arrays from the spatial coordinate data holding unit,
determine combination of the microphone arrays for forming directionality toward the selected one or more target areas and combination of the microphones which form a bidirectionality and a unidirectionality in the microphone arrays, and
control a signal to be input to the directionality forming unit.

3 . The sound pickup apparatus according to claim 1 , further comprising:
a delay correcting unit configured to perform a correction process that absorbs a difference in propagation delay times of the target area sound to the microphone arrays between outputs of the microphone arrays from the directionality forming unit.

4 . A method of picking up sound in a computer system including a plurality of microphone arrays each including three microphones disposed at vertexes of a triangle, comprising:
forming, by a directionality forming unit, directionality only in a forward direction of each of the microphone arrays with respect to a target area by use of beamformers for each output from each of the microphone arrays; forming, by the bidirectionaly forming unit, a bidirectionality having a dead angle in a target direction by use of a sound signal picked up by two microphones which are located to be horizontal with respect to the target direction, among three microphones disposed at vertexes of an isosceles right triangle; forming, by a unidirectionality forming unit, a unidirectionality having a dead angle in the target direction by use of a sound signal picked up by two microphones which are located in a same direction as the target direction, among the three microphones; extracting a target sound by performing a spectral subtraction of all outputs from the bidirectionality forming unit and the unidirectionality forming unit from either one of sound signals picked up by the two microphones located to be horizontal with respect to the target direction or a signal obtained by averaged sound signals picked up by the two microphones; calculating, by a power correction coefficient calculating unit, with respect to each frequency, a ratio of amplitude spectra of beamformer outputs between outputs for each of the microphone arrays from the directionality forming unit; setting a mode or a median of the calculated ratio of amplitude spectra as a correction coefficient which corrects power of beamformer outputs for each of the microphone arrays; and extracting, by a target area sound extracting unit, a target area sound by performing the following processes in sequence:
correcting a beamformer output from each of the microphone arrays from the directionality forming unit by use of the correction coefficient calculated by the power correction coefficient calculating unit,
performing a spectral subtraction of the beamformer output from each of the microphone arrays, the beamformer output being obtained by the correction, to extract a non-target area sound which is present in the target area direction when seen from each of the microphone arrays, and
performing a spectral subtraction of the extracted non-target area sound from the beamformer output from each of the microphone arrays from the directionality forming unit.

Assignees

• Oki Electric Ind Co Ltd

Inventors

• Katagiri Kazuhiro

Classifications

• H04R1/326

  for microphones (H04R1/34 and H04R1/40 take precedence) · CPC title

• H04R2430/03

  Synergistic effects of band splitting and sub-band processing · CPC title

• H04R2201/401

  2D or 3D arrays of transducers · CPC title

• H04R2203/00

  Details of circuits for transducers, loudspeakers or microphones covered by H04R3/00 but not provided for in any of its subgroups · CPC title

• H04R1/20

  Arrangements for obtaining desired frequency or directional characteristics (for stereophonic purpose H04R5/00) · CPC title