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JP-2026075528-A - Microphone device

JP2026075528AJP 2026075528 AJP2026075528 AJP 2026075528AJP-2026075528-A

Abstract

[Problem] To provide a microphone device that can adjust the sharpness of its directivity. [Solution] The microphone device 1 comprises two front microphones arranged in a front row along a first direction, one rear microphone arranged in a rear row behind the front row, a frequency conversion unit that converts the signals obtained from the two front microphones and the rear microphone into the frequency domain, a front extraction processing unit that extracts signals from frequency bins where the phase difference between at least one signal from the two front microphones and the signal from the rear microphone is positive, a front extraction processing unit that extracts signals from frequency bins where the phase difference between one signal from the two front microphones and the signal from the other falls within a predetermined range, an output spectrum calculation unit that obtains an output spectrum based on the extraction results of the front extraction processing unit and the front extraction processing unit, and an inverse frequency conversion unit that converts the output spectrum into a time domain signal, wherein the front extraction processing unit sets a predetermined range based on a parameter indicating the sharpness of the directivity. [Selection Diagram] Figure 3

Inventors

  • 大川 僚太

Assignees

  • 株式会社トランストロン

Dates

Publication Date
20260508
Application Date
20241022

Claims (7)

  1. Two front microphones are positioned in the front row along the first direction, A rear microphone is provided in the rear row, which is positioned along the first direction and behind the front row, A frequency conversion unit that converts the signals obtained by the two front microphones and the signals obtained by the rear microphone into the frequency domain, A forward extraction processing unit extracts signals from the frequency domain of the signal converted to the frequency domain by the frequency conversion unit, where the phase difference between the signal obtained by at least one of the two forward microphones and the signal obtained by the rear microphone is positive. A front extraction processing unit extracts signals from the frequency domain of the signal converted to the frequency domain by the frequency conversion unit, wherein the phase difference between the signal obtained by one of the two front microphones and the signal obtained by the other microphone is within a predetermined range. An output spectrum calculation unit that obtains an output spectrum based on the results extracted by the forward extraction processing unit and the forward extraction processing unit, An inverse frequency converter that converts the output spectrum into a time-domain signal, A reception unit that accepts parameters indicating the sharpness of directivity, Equipped with, The microphone device is characterized in that the front extraction processing unit causes the predetermined range to differ based on the parameters received by the reception unit.
  2. The system further includes a virtual microphone processing unit that calculates a virtual signal obtained by a virtual microphone virtually positioned at the foot of a perpendicular line drawn from the rear microphone to the virtual line segment connecting the two front microphones, based on the signals obtained by the two front microphones. The microphone device according to claim 1, characterized in that the forward extraction processing unit extracts the signal of the frequency bin in which the phase difference between the virtual signal and the signal obtained by the rear microphone is positive.
  3. The system further includes a synchronization subtraction unit that calculates the arrival time for sound reaching one of the virtual microphones and the rear microphone to reach the other, based on the distance between the virtual microphone and the rear microphone, and calculates a synchronization subtraction signal by subtracting a delayed signal obtained by the rear microphone, which is delayed by the arrival time, from the virtual signal. The forward extraction processing unit extracts the signal of the frequency bin where the phase difference between the virtual signal and the signal obtained by the rear microphone is positive. The microphone device according to claim 2, characterized in that the output spectrum calculation unit obtains the output spectrum based on the synchronous subtraction signal and the results extracted by the forward extraction processing unit and the frontal extraction processing unit.
  4. The microphone device according to claim 2, characterized in that the output spectrum calculation unit obtains the output spectrum based on the virtual signal and the results extracted by the forward extraction processing unit and the front extraction processing unit.
  5. It further includes a synchronous subtraction unit that calculates a synchronous subtraction signal, The triangle formed by the rear microphone and the two front microphones is a right-angled triangle. The rear microphone and the first front microphone, which is one of the two front microphones, are located on a line along a second direction perpendicular to the first direction. The forward extraction processing unit extracts the signal of the frequency bin where the phase difference between the signal obtained by the first forward microphone and the signal obtained by the rear microphone is positive. The synchronous subtraction unit calculates the arrival time for sound that has reached one of the first front microphone and the rear microphone to reach the other, based on the distance between the first front microphone and the rear microphone, and calculates the synchronous subtraction signal by subtracting a delayed signal obtained by delaying the signal obtained by the rear microphone by the arrival time from the signal obtained by the first front microphone. The microphone device according to claim 1, characterized in that the output spectrum calculation unit obtains the output spectrum based on the synchronous subtraction signal and the results extracted by the forward extraction processing unit and the front extraction processing unit.
  6. The triangle formed by the rear microphone and the two front microphones is a right-angled triangle. The rear microphone and the first front microphone, which is one of the two front microphones, are located on a line along a second direction perpendicular to the first direction. The forward extraction processing unit extracts the signal of the frequency bin where the phase difference between the signal obtained by the first forward microphone and the signal obtained by the rear microphone is positive. The microphone device according to claim 1, characterized in that the output spectrum calculation unit obtains the output spectrum based on the signal obtained by the first front microphone and the results extracted by the front extraction processing unit and the front extraction processing unit.
  7. The microphone device according to any one of claims 1 to 6, wherein the front extraction processing unit extracts signals from frequency bins whose phase difference between the two front microphones falls within a predetermined range, using a frequency mask that extracts signals from frequency bins whose phase difference falls within a predetermined range, wherein the value of the frequency mask smoothly decreases as it approaches the threshold.

Description

This invention relates to a microphone device. Patent Document 1 discloses a sound acquisition device that calculates the ratio of the amplitude spectrum of the sound in the target area to the amplitude spectrum of the input signal of the microphone array for each frequency, then uses the sum of the amplitude spectrum ratios for each frequency and the sum of the coherence values for each frequency to determine whether or not sound is present in the target area, and outputs the extracted sound from the target area if sound is present. Patent No. 6065030 This is a schematic diagram of an example of a microphone device 1.This diagram illustrates the general processing flow in microphone device 1.This is a block diagram showing the schematic electrical configuration of microphone device 1.This diagram schematically shows the positional relationship of the virtual microphones calculated based on the first front microphone 11 and the second front microphone 12.This figure shows an example of a directional pattern after synchronous subtraction.This diagram schematically shows an example of a frequency mask.This figure shows an example of a directional pattern when forward extraction is performed using a frequency mask.This diagram schematically shows an example of a frequency mask.This is a schematic diagram illustrating the maximum angle θ.This diagram schematically shows an example of a frequency mask.This figure shows an example of a directional pattern when frontal extraction is performed using a frequency mask.This figure shows an example of a simulation result of the directional pattern of sound picked up by microphone device 1.This figure shows an example of a simulation result of the directional pattern of sound picked up by microphone device 1.This figure shows an example of a simulation result of the directional pattern of sound picked up by microphone device 1.This figure shows an example of a simulation result of the directional pattern of sound picked up by microphone device 1.This figure shows an example of the microphone arrangement of microphone device 1A.This figure shows an example of the microphone arrangement of microphone device 1B.This is a schematic diagram illustrating the angles θ1 and θ2 when directing the beam in a direction other than directly in front.This diagram schematically shows an example of a frequency mask when directing the beam in a direction other than directly in front.This diagram illustrates the general processing flow of the microphone device 2.This is a block diagram showing the schematic electrical configuration of the microphone device 2. Hereinafter, embodiments of the microphone device according to the present invention will be described in detail with reference to the drawings. The microphone device according to the present invention is a device that can pick up only the target sound from a specific direction. <First Embodiment> Figure 1 is a schematic diagram of the microphone device 1. The microphone device 1 mainly comprises a first front microphone 11, a second front microphone 12, and a rear microphone 13. Of the target sound to be picked up by the microphone device 1, the sound waves from the front of the microphone device 1 are assumed to travel from the bottom to the top in the figure. Hereafter, the direction from the microphone device 1 toward the front (from top to bottom in Figure 1) will be referred to as the front, and the opposite direction (from bottom to top in Figure 1) will be referred to as the rear. Furthermore, looking from the front to the rear, the direction toward the right will be referred to as the rightward direction, and the direction toward the left will be referred to as the leftward direction. The direction from right to left and from left to right will be referred to as the first direction, and the direction from front to rear and from rear to front will be referred to as the second direction. The first and second directions are perpendicular to each other. Note that the line connecting the first front microphone 11 and the second front microphone 12 aligns with the left-right direction (first direction). The first front microphone 11, the second front microphone 12, and the rear microphone 13 are omnidirectional microphones. The first front microphone 11, the second front microphone 12, and the rear microphone 13 have equivalent configurations; for example, MEMS microphones can be used. The first front microphone 11, the second front microphone 12, and the rear microphone 13 are housed, for example, inside the housing 20. The housing 20 is provided with appropriate sound holes at positions corresponding to each of the first front microphone 11, the second front microphone 12, and the rear microphone 13. The first front microphone 11 and the second front microphone 12 are located in the front row of the microphone device 1. Here, the front row refers to the arrangement located towards the front of the arrangement along the first dir