Device and method for determining a sound source direction

Patent metadata

Field	Value
Publication number	US-10609479-B2
Application number	US-201816127601-A
Country	US
Kind code	B2
Filing date	Sep 11, 2018
Priority date	Sep 14, 2017
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

A device for determining a sound source direction determines a direction in which a source of a reached sound exists, based on at least one of a sound pressure difference between a first sound pressure that is a sound pressure of a first frequency component of a first part of the reached sound acquired by a first microphone and a second sound pressure that is a sound pressure of the first frequency component of a second part of the reached sound acquired by a second microphone, and a phase difference between a first phase that is a phase of a second frequency component of the first part of the reached sound and a second phase that is a phase of the second frequency component of the second part of the reached sound.

First claim

What is claimed is:

1. A device for determining a sound source direction, the device comprising:
a case in which a first sound path, which has a first opening opened in a first surface at a first end of the first sound path and in which a sound is propagated from the first opening, and a second sound path, which has a second opening opened in a second surface crossing the first surface at a first end of the second sound path and in which a sound is propagated from the second opening, are provided;
a first omnidirectional microphone provided at a second end of the first sound path;
a second omnidirectional microphone provided at a second end of the second sound path;
a memory; and
a processor coupled to the memory and the processor configured to:
determine a direction in which a source of a reached sound exists, based on a sound pressure difference between a first sound pressure that is a sound pressure of a first frequency component of a first part of the reached sound acquired by the first omnidirectional microphone and a second sound pressure that is a sound pressure of the first frequency component of a second part of the reached sound acquired by the second omnidirectional microphone, and a phase difference between a first phase that is a phase of a second frequency component of the first part of the reached sound and a second phase that is a phase of the second frequency component of the second part of the reached sound, wherein the first frequency component ranges from 3000 Hz to 8 kHz.

2. The device according to claim 1 , wherein the first surface is orthogonal to the second surface, an area of the first surface is equal to or smaller than a first predetermined value, an area of the second surface is larger than the first predetermined value, the first sound path includes a first diffraction portion, which diffracts the sound in the first opening and a second diffraction portion, which diffracts the sound and is a bent portion, in the middle of the first sound path, and the second sound path includes a third diffraction portion, which diffracts the sound in the second opening.

3. The device according to claim 1 , wherein the first surface is orthogonal to the second surface, an area of the first surface is equal to or smaller than a first predetermined value, an area of the second surface is larger than the first predetermined value, the first sound path includes a first diffraction portion, which diffracts the sound in the first opening and a second diffraction portion, which diffracts the sound and is a bent portion, in the middle of the first sound path, and the second sound path includes a third diffraction portion, which diffracts the sound in the second opening and a fourth diffraction portion, which diffracts the sound and is a bent portion, in the middle of the second sound path.

4. The device according to claim 1 , wherein the first surface is orthogonal to the second surface, areas of the first surface and the second surface are larger than a first predetermined value, the first sound path includes a first diffraction portion, which diffracts the sound in the first opening, and the second sound path includes a second diffraction portion, which diffracts the sound in the second opening.

5. The device according to claim 1 , wherein the sound pressure difference is an average value of sound pressure differences obtained by subtracting a logarithm of power of the second sound pressure from a logarithm of power of the first sound pressure,
wherein the phase difference is an average value of phase differences of a target frequency band, and
wherein the processor determines that the source of the reached sound exists at a position opposite to the first surface in at least one case between a case where an average value of the sound pressure differences is larger than a first threshold value, which is a plus value, and a case where an average value of the sound pressure differences is larger than a third threshold value, which is a plus value.

6. The device according to claim 5 , wherein the processor determines that the source of the reached sound exists at a position opposite to the second surface in at least one case between a case where the average value of the sound pressure differences is smaller than a negative second threshold value, and a case where the average value of the sound pressure differences is smaller than a negative fourth threshold value.

7. The device according to claim 5 , wherein a phase that is an average value of the phase differences of the target frequency band is expressed by Equation (10) below,
a _phrase=(Σ j=ss ee phase[ j ]· C _ n [ j ])/( ee+ 1− ss )  (10)

herein, phase[j]=atan(phase_im[j]/phase_re[j]), phase_re[j]=re1[j]×re2[j]+im1[j]×im[j], phase_im[j]=im1[j]×re2[j]−re1[j]×im2[j], C_n[j]=A[j]/λ_c, j is a frequency band number, re1[j] is an actual part of spectrum of the first sound pressure in a jth frequency band, re2[j] is an actual part of spectrum of the second sound pressure in the jth frequency band, im1[j] is an imaginary part of spectrum of the first sound pressure in the jth frequency band, im2[j] is an imaginary part of spectrum of the second sound pressure in the jth frequency band, λ[j] is a wavelength of a sound of the jth frequency band, λ_c is a wavelength of a sound at a reference frequency, ee is an upper-limit of the target frequency band, and ss is a lower-limit of the target frequency band.

8. The device according to claim 1 , wherein the sound pressure difference is a sound pressure difference average value, which is an average value of a plurality of frames of the sound pressure difference for each frame obtained by subtracting a logarithm of power of the second sound pressure from a logarithm of power of the first sound pressure,
wherein the phase difference is a phase difference average value, which is an average value of a plurality of frames of the phase difference in a target frequency band for each frame,
wherein the processor determines that the source of the reached sound exists at a position opposite to the first surface in at least one case of the case where the sound pressure difference average value is larger than a fifth threshold value and the phase difference average value is larger than a sixth threshold value,
wherein the fifth threshold value is an average value of the sound pressure difference average value when the source of the reached sound exists at a position opposite to the first surface and the sound pressure difference average value when the source of the reached sound exists at a position opposite to the second surface, and
wherein the sixth threshold value is an average value of the phase difference average value when the source of the reached sound exists at a position opposite to the first surface and the phase difference average value when the source of the reached sound exists at a position opposite to the second surface.

9. The device according to claim 8 , wherein, in at least one of a case where the sound pressure difference average value is equal to or smaller than the fifth threshold value and a case where the phase difference average value is equal to or smaller than the sixth threshold value, the processor determines that the source of the reached sound exists at a position opposite to the second surface.

10. The device according to claim 8 , wherein an average value of the sound pressure difference average value when the source of the reached sound exists at the position opposite to the first surface and the sound pressure difference average value when the source of the reached sound exists at the position opposite to the second surface is an average value of a first average value, which is an average valu

Assignees

• Fujitsu Ltd

Inventors

• Shioda Chisato
• Washio Nobuyuki
• Suzuki Masanao
• Takeuchi Shunsuke
• Tsuchinaga Yoshiteru

Classifications

• G10L25/21

  the extracted parameters being power information · CPC title

• G10L25/18

  the extracted parameters being spectral information of each sub-band · CPC title

• H04R1/406

  microphones · CPC title

• H04R2430/20

  Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) · CPC title

• H04R3/005 Primary

  for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407) · CPC title