JP5889752B2 - Artificial movable ear device and method for specifying sound source direction - Google Patents

Description

  The present invention relates to an auditory assist device that supports a human auditory function. More specifically, the present invention relates to an artificial movable ear device that can be used by the auditory assist device and that can specify a sound source direction and that can be worn by a person. The present invention relates to a method for specifying a sound source direction used in an artificial movable ear device.

  Conventionally, a hearing aid used as a hearing assist device has only a function of processing and amplifying input sound and transmitting it to a person. However, in such a conventional hearing aid, for example, a sound source for realizing a higher function such as causing the wearer to recognize the direction of the sound source or notifying the monitor whether the wearer recognizes the presence of the sound source. Information about the direction cannot be provided to the user.

  On the other hand, although it is not intended to be worn and used by a person, as a device for specifying the direction of a sound source, for example, Patent Document 1 discloses that a sound source that emits sound only for a short time is 3 of the sound source. For the purpose of constructing an inexpensive device capable of estimating the dimensional direction, the microphone b is provided with three microphones a, b, c, and the microphone b is placed at a position away from the reference microphone a in the horizontal direction. The microphones b and c are acquired by switching between the microphone b and the microphone c at a predetermined short period while arranging the sound data acquired by the microphone a in the storage device, respectively, in a position separated from each other in the vertical direction. Sound data is stored in the storage device, and the direction (azimuth angle) of the sound source in the horizontal plane is calculated from the sound data of the microphones a and b stored in the storage device. And calculates the direction (elevation angle) from the sound data stored microphone a microphone c in the storage device in the vertical plane of the sound source, "speech direction estimating apparatus and method" is disclosed.

  As a hearing device for a robot, for example, Patent Document 2 has a microphone and an auricular structure at the positions of both ears, and the auricular structure has a conical outer ear structure that collects sound. And an acoustic shielding means for shielding noise generated by the head itself (for example, noise from a fan provided in the head), and the microphone is disposed at an acoustic center position of the outer ear structure portion. A “robot head having an artificial ear” is known. Further, this document discloses that an actuator for directing the robot head itself toward the sound source is provided.

  However, since the apparatus described in Patent Document 1 uses three microphones, it is difficult to arrange them on a person's head as a hearing assistance apparatus. Further, since the direction of the microphone is fixed, when the sound source deviates from the sensitivity direction of the microphone, the SN ratio of the sound data is deteriorated, and an error is likely to occur in the specification of the sound source direction.

  Further, in the robot head described in Patent Document 2, since the sensitivity direction of the microphone is fixed with respect to the head surface (for example, in the normal direction), both of the two microphones cannot be directed in the sound source direction. Since it is difficult to minimize the S / N ratio of sound data from the target sound source as in the technique of Reference 1, there is still room for improvement with regard to improving the accuracy of sound source direction estimation.

JP 2005-49153 A JP 2008-5472 A

  Against the background of the above-described conventional technology, aiming to realize higher functions of the hearing assist device, a device that functions as a part of the hearing assist device and that can be worn by a person and can accurately specify the sound source direction. Realization is required.

One aspect of the present invention includes a plurality of microphones, the provided plurality of respective microphones, and an actuator for changing the direction of the microphone, based on the current state of the prior SL actuator, the current of the microphone Calculate the position, calculate the phase difference between the microphones of the sound from the sound source acquired by the microphone, calculate the distance between the microphones at the current position of the microphone, and the calculated A control device that calculates a direction of the sound source based on a phase difference and controls the actuator so that a direction of each microphone is directed to the calculated direction of the sound source, and the control device includes: Assuming that the frequencies with the maximum power contained in each sound acquired from each microphone match each other. Te, is configured to calculate the phase difference in the frequency, it is an artificial movable ear device.
In another aspect of the present invention, the control device performs low-pass filtering that removes a frequency exceeding the frequency having the maximum power from each sound acquired from each microphone, and each sound after the low-pass filtering is performed. The artificial movable ear device is configured to calculate a difference in time at which the waveform becomes a minimum value as the phase difference.
In another aspect of the present invention, the low-pass filtering is performed by performing a moving average calculation on digital data obtained by converting each sound acquired from each microphone at a predetermined time interval. Ear device.
Another aspect of the present invention is the artificial movable ear device in which the actuator is configured by a motor that rotates the microphones around two axes intersecting at a predetermined angle.
In another aspect of the present invention, the direction of the sound source is projected in the direction of the sound source projected in the sagittal plane of the wearer wearing the artificial movable ear device or in a horizontal plane orthogonal to the sagittal plane. This is an artificial movable ear device in the direction of the sound source.
Another aspect of the present invention includes a plurality of microphones, an actuator provided in each of the plurality of microphones, and a control device that changes a direction of the microphone, and the control device is a current device of the actuator. A device for calculating the current position of the microphone, a device for calculating a phase difference between the microphones of a sound source acquired by the microphone, and the calculated microphone. Based on the distance between the microphones at the current position and the calculated phase difference, a device that calculates the direction of the sound source, and the direction of each microphone is directed toward the calculated direction of the sound source. comprising a device for controlling the actuator, a device for calculating the phase difference, the respective Mai On condition that the frequency having the maximum power contained in each sound acquired from Rohon coincide with each other, to calculate the phase difference in the frequency, it is an artificial movable ear device.
According to another aspect of the present invention, a step of calculating a current position of each of the plurality of microphones based on a current state of each actuator that respectively changes the direction of the microphone provided in the plurality of microphones; Calculating the phase difference between the microphones of the sound from the sound source obtained by the step, based on the calculated distance between the microphones at the current position of the microphone and the calculated phase difference. Calculating the direction of the sound source, and controlling the actuator so that the direction of each microphone is directed to the calculated direction of the sound source, and calculating the phase difference, The frequencies having the maximum power included in each sound acquired from each microphone match each other. On condition that, to calculate the phase difference in the frequency, a sound source direction of a particular method.

  According to the present invention, the direction of the sound source can be accurately identified by a device that can be worn by a person.

It is a figure which shows the whole structure of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a figure which shows the structure of the parabolic pinna of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a figure which shows the definition of the angle in the rotation plane of two motors in order to represent the direction of a microphone in the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the whole operation | movement of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a figure which shows the movement system of the microphone of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the MIC position calculation process of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the phase difference calculation process of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is explanatory drawing for demonstrating the method to specify the sound source direction in a horizontal surface in the artificial movable ear | edge apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the sound source direction calculation process of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the procedure of the MIC direction control process of the artificial movable ear apparatus which concerns on one Embodiment of this invention. It is a figure which shows the observation result of the sound source direction specific operation | movement in the artificial movable ear apparatus which concerns on one Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing the overall configuration of an artificial movable ear according to an embodiment of the present invention.
The artificial movable ear device 1 includes a headband 2 having a substantially circular curved portion that is worn on a user's head, and a predetermined distance to the left and right symmetrical positions across the center of the headband 2. Two parabolic auricles 4 </ b> L and 4 </ b> R provided at a distance from each other, a control device 6 disposed in the headband 2, and a battery 8 for supplying power to the control device 6 are also provided.

  The artificial movable ear device 1 shown in FIG. 1 is worn by a user with the user's face facing the front of the page. Here, FIG. 1 is defined as a front view of the artificial movable ear device 1. The Z axis shown in FIG. 1 is the symmetry axis of the headband 2. The axis orthogonal to the Z axis and extending in the normal direction of the paper surface from the back surface to the front surface is the X axis, orthogonal to the X axis and Z axis, and the paper surface from the right. The axis extending to the left is the Y axis. Thereby, the sagittal surface of the user when the headband 2 is worn becomes the ZX plane.

  The two parabolic auricles 4L and 4R described above are arranged in a substantially circular curved portion of the headband 2, and the center lines of the parabolic auricles 4L and 4R are 45 in a direction opposite to the Z axis, respectively. Tilt by only °. The parabolic auricles 4L and 4R have the same configuration. Therefore, when these are collectively referred to without distinction between left and right, they are referred to as “parabolic auricles 4”.

FIG. 2 is a configuration diagram showing the configuration of the parabolic auricle 4. 2A and 2B are a front view and a side view of the parabolic auricle 4, respectively.
The parabolic auricle 4 includes an auricular portion 20 processed into a parabolic shape, and a microphone 24 disposed on a substantially center line of a parabolic curved surface of the auricular portion 20 via a bracket 22 provided on the auricular portion 20. And motors 26 and 28 for rotating the auricle portion 20 around two orthogonal axes.

  The main body portion of the motor 26 is fixed to a corresponding position on the headband 2 via a support 30. The main body of the motor 28 is fixed to the rotating shaft of the motor 26 via the holder 32, and the rotating shaft of the motor 26 and the rotating shaft of the motor 28 are arranged so as to be orthogonal to each other. The rotation axis of the motor 28 is fixed to a bracket 34 provided on the back surface of the auricle portion 20. Thus, by appropriately controlling the rotation angles of the motors 26 and 28, the direction of the parabolic auricle 4 and thus the direction of the microphone 24 can be rotated around two axes orthogonal to each other. Here, “the direction of the microphone 24” refers to the direction in which the microphone 24 has the highest acoustoelectric conversion sensitivity in relation to the acoustic reflection by the microphone 24 itself or the parabolic auricle portion 20.

  The xyz coordinate system shown in FIG. 2 uses the position of the microphone 24 as the origin, the axis parallel to the X axis in FIG. 1 as the x axis, the axis perpendicular to the x axis and parallel to the tangential direction of the hairband 2 as the x axis, It is defined as a coordinate system in which an axis orthogonal to the axis and the y axis is the z axis. Here, the rotation axis of the motor 26 is set to face the z-axis direction, and therefore the rotation plane of the microphone 24 by the motor 26 is the xy plane. Further, the rotation axis of the motor 28 is set to face the y-axis direction, and therefore the rotation plane of the microphone 24 by the motor 26 is the zx plane.

  In the present embodiment, the motors 26 and 28 are servo motors provided with potentiometers, and the current rotation angle of the motors can be measured from the resistance values of the potentiometers. In place of the servo motor, the motors 26 and 28 may be pulse motors. In this case, the angle information of the pulse motor can be obtained by storing the number of drive pulses applied to the pulse motor in the control device 6, for example.

Here, angles θ _h and θ _v in the rotation planes of the motors 26 and 28 for representing the direction of the microphone 24 are defined as shown in FIG. That is, the angle measured from the x-axis in the y-axis direction is defined as θ _h , and the angle measured from the x-axis in the z-axis direction is defined as θ _v with the x-axis as the reference axis. The reference direction of the rotation angle of the motor 26 and 28, when the microphone 24 is assumed to be set to correspond to a state facing the x-axis direction, the rotation angle of the motor 26 is theta _h, xy microphone 24 angle theta _h next in the plane, when the rotation angle theta _v of the motor 28, it is assumed that the angle at the zx plane of the microphone 24 becomes a theta _v.

In the following description, when referring to the structural elements such as the motor 26 while distinguishing the left and right parabolic auricles 4L and 4R, the reference numerals representing the structural elements are denoted by L or R, respectively. indicated as such "motor 26L""motor26R", for the rotation angle theta _h and theta _v of the motor 26 and 28, left and right motors 26L, when referring distinguished as rotation angle of the 26R or the like, the suffix L or R It shall be described as “θ _Lh ”, “θ _Rh ”, etc.

FIG. 4 is a block diagram showing the configuration of the control device 6.
The control device 6 is a computer having a central processing unit (CPU) 40, a ROM 41, and a RAM 42, an AD converter (Analog-to-Digital converter) 44, a timer 46, and an input. An output interface 48. The control device 6 can be configured using, for example, a one-chip microcomputer or a digital signal processor (DSP).

  The acoustic signals acquired from the microphones 24L and 24R are respectively input to the AD converter 44, sampled at a predetermined time interval based on the sampling signal output from the timer 46, converted into a digital signal (acoustic data), and stored in the RAM 42. Stored in chronological order. It should be noted that the RAM 42 holds only a predetermined number of the most recently sampled sound data, that is, only the sound data acquired within the most recent predetermined time. When new sound data is stored, the oldest data is erased. Is done. As a result, the acoustic data sequence in the RAM 42 is constantly updated at the sampling period.

  The control device 6 includes a microphone (MIC) position calculation unit 402, a phase difference calculation unit 404, a sound source direction calculation unit 406, and a microphone (MIC) for performing processing and control on the microphone 24 and the motors 26 and 28. A direction control unit 408. In the present embodiment, the functions of the respective units (reference numerals 402 to 408) are realized by the CPU 40 included in the control device 6 executing the program. In addition, these calculation parts (code | symbol 402-406) and a control part (code | symbol 408) can also be comprised as one or several devices which have hardware, such as an electric circuit.

  The MIC position calculation unit 402 acquires the current rotation angles of the motors 26 and 28 via the input / output interface 48, and based on these rotation angles, the kinema about the motion system of the microphone 24 that the parabolic auricle 4 configures. Tick calculation is performed to calculate the current position coordinates of the left and right microphones 24L and 24R. Details of this calculation method will be described later.

The phase difference calculation unit 404 calculates the phase difference between the acoustic waveforms acquired by the microphones 24L and 24R. A method for calculating the phase difference will be described later.
The sound source direction calculation unit 406 is based on the phase difference calculated by the phase difference calculation unit 404 and the current position coordinates of the microphones 24L and 24R calculated by the MIC position calculation unit 402, and the direction of the sound source (azimuth angle and elevation angle). Is calculated.

  The MIC direction control unit 408 controls the motors 26L, 28L, and 26R, 28R via the input / output interface 48, thereby moving the directions of the microphones 24L and 24R to the direction of the sound source calculated by the sound source direction calculation unit 406. Turn.

  The artificial movable ear device 1 having the above configuration can specify the sound source direction with high accuracy by repeating the calculation of the sound source direction and the control for directing the direction of the microphone 24 in the calculated direction.

Next, the operation of the artificial movable ear device 1 will be described.
FIG. 5 is a flowchart showing the procedure of the overall operation of the artificial movable ear device 1. This process starts when the artificial movable ear device 1 is turned on.

  When the power is turned on, the control device 6 executes the MIC position calculation process (S1), calculates the current position coordinates of the microphones 24L and 24R, and then executes the phase difference calculation process (S2). Thus, the phase difference between the sounds detected by the two microphones 24L and 24R is calculated. Subsequently, the control device 6 executes a sound source direction calculation process (S3), and determines the direction of the sound source from the current position coordinates of the microphones 24L and 24R calculated in step S1 and the phase difference of the sound calculated in step S2. Is calculated. Thereafter, the control device 6 executes MIC direction control processing (S4), controls the motors 26L, 28L, 26R, and 28R, and changes the directions of the microphones 24L and 24R to the direction of the sound source calculated in step S3. Then, the process returns to step S1 to repeat the process. In addition, this process is complete | finished when the power supply of the artificial movable ear apparatus 1 is cut off.

Next, the contents of each process shown in steps S1 to S4 will be described in order.
First, the MIC position calculation process (step S1 in FIG. 5) will be described. Since the contents of the MIC position calculation process are the same for the parabolic auricles 4L and 4R, these will be collectively referred to as the parabolic auricles 4. Actually, the current position coordinates of the microphones 24L and 24R are calculated by performing the following MIC position calculation processing for the left and right parabolic auricles 4L and 4R, respectively.

FIG. 6 is a diagram schematically showing the motion system of the microphone 24.
In FIG. 6, a perpendicular drawn from the node 500 indicating the position of the microphone 24 to the rotation shaft 502 of the motor 28 is an arm 504, and a point where the arm 504 is connected to the rotation shaft 502 of the motor 28 is a joint 506. Further, an intersection between the rotation shaft 502 of the motor 28 and the rotation shaft 508 of the motor 26 is a joint 510, and a section from the joint 506 to the joint 510 along the rotation shaft 502 is an arm 512.

Further, the position vector of the joint 510 is P1, the position vector of the joint 506 is P2, the position vector of the node 500 is P3, the position vector of the initial position of the joint 506 is P20, and the position vector of the initial position of the node 500 is P30. . Here, the “initial position of the joint 506” refers to the position of the joint 506 when the rotation angle θ _h of the motor 26 is 0 °, and the “initial position of the node 500” refers to the rotation of the motors 26 and 28. The position of the node 500 when the angles θ _h and θ _v are both 0 ° is assumed. Further, the above-described position vector means a position vector starting from the origin O in the XYZ coordinates shown in FIG. 1 unless otherwise specified.

Here, R ₁ (θ _v ) is a rotation matrix representing the position change of the node 500 due to rotation around the rotation axis 502 (rotation of the motor 28), and the joint 506 and node due to rotation around the rotation axis 508 (rotation of the motor 26). If the rotation matrix representing the position change of 500 is R ₂ (θ _h ), the current position vector P3 of the microphone 24 is given by the following equation.
P3 ＝ R1 (θ _v ) ・ (P3'−P2) + P2 (1)
here,
P2 ＝ R2 (θ _h ) ・ (P20−P1) + P1 (2)
P3 '＝ R2 (θ _h ) ・ (P30−P1) + P1 (3)
It is. Note that the position vector such as P1 is a three-dimensional column vector.

In the above equation, the position vector P2 of the joint 506 and the position vector P3 ′ of the node 500 when only the motor 26 rotates by the angle θ _h are obtained by the equations (2) and (3), respectively, as the position at which the further motor 28 from the position of P3' is rotated by an angle theta _v, seeking position vector P3 of the node 500 of the current microphone 24.

FIG. 7 is a flowchart showing the procedure of the MIC position calculation process.
First, the MIC position calculation unit 402 of the control device 6 acquires the current rotation angles θ _h and θ _v of the motors 26 and 28 included in the parabolic auricle 4 (S101), and acquires the acquired rotation angles θ _h and θ _v. Is used to calculate the rotation matrices R ₁ (θ _v ) and R ₂ (θ _h ) (S102), and then the current position coordinates of the microphones 24L and 24R are calculated using equation (1) (S103), and the process is performed. finish. Here, as described above, the rotation angles θ _h and θ _v can be obtained using the potentiometers provided in the motors 26 and 28, respectively.

Next, the phase difference calculation process (step S2 in FIG. 5) will be described.
As described above, the RAM 42 stores, for each of the microphones 24L and 24R, a predetermined number of acoustic data acquired within the most recent predetermined time in order of time, and is stored as an acoustic data sequence. The acoustic data sequence is constantly updated by storing the newest acoustic data and deleting the oldest acoustic data in synchronization with the sampling period of the AD converter 44. Hereinafter, the acoustic data based on the acoustic signal from the microphone 24L is referred to as “left acoustic data”, and the acoustic data based on the acoustic signal from the microphone 24R is referred to as “right acoustic data”.

FIG. 8 is a flowchart showing the procedure of the phase difference calculation process.
First, for each of the left and right acoustic data sequences stored in the RAM 42, the phase difference calculation unit 404 performs discrete Fourier transform using a subset of acoustic data composed of the latest consecutive predetermined number (N) of acoustic data. Conversion is performed (S201). For example, in the left acoustic data, this discrete Fourier transform is given by
D _L1 = W · D _L0 (4)

Here, D _L0 is an input vector (N-dimensional column vector) composed of left acoustic data dL _n (n = 0, 1,..., N−1), and D _L1 is included in the acoustic signal represented by the input data. Frequency vectors (N-dimensional column vectors) composed of frequencies f _k (k = 0, 1,..., N−1),
D _L0 = (dL ₀ , dL ₁ , ..., dLn, ..., dL _N-1 ) ^T (5)
D _L1 = (f ₀ , f ₁ , ..., f _k , ..., f _N-1 ) ^T (6)
Given in.

なお、右の音響データの離散的フーリエ変換も、上記と同様の式を用いて行うことができる。また、ステップＳ２０１における離散的フーリエ変換は、所定数Ｎを２のべき乗で表わされる数とすることにより、公知の高速フーリエ変換アルゴリズムを用いて行うことができる。 W is an N × N coefficient matrix of discrete Fourier transform, and an element w _kn of k rows and n columns is given by the following equation.

Note that the discrete Fourier transform of the right acoustic data can also be performed using the same formula as described above. The discrete Fourier transform in step S201 can be performed using a known fast Fourier transform algorithm by setting the predetermined number N to a number represented by a power of 2.

  Next, based on the result of the Fourier transform, the phase difference calculation unit 404 identifies the frequencies having the maximum power (hereinafter referred to as the maximum power frequency) for each of the left and right acoustic data sequences (S0202), and these maximum power frequencies. Are determined to match each other (S203).

  In step S203, when the maximum power frequencies calculated from the left and right acoustic data sequences are different from each other (S203, No), the process returns to step S201, and the process is repeated using a subset of the latest acoustic data sequence. .

  On the other hand, in step S203, when the maximum power frequencies calculated from the left and right acoustic data sequences match each other (S203, Yes), the left and right acoustic data sequences are acquired within a period equal to the period of the maximum power frequency. A moving average value is calculated using a subset of all (r) consecutive acoustic data, and the calculated moving average values of the left and right acoustic data are respectively stored in the RAM 42 in time order (S204). As a result, a sequence of moving average values is stored in the RAM 42.

For example, the moving average value AL (i) for the left acoustic data sequence (moving average value calculated by r acoustic data subsets from i-th to (i + r−1) -th in the RAM 42) is expressed by the following equation. (The moving average value AR (i) of the right acoustic data is also given by the same equation).

  Converting an acoustic data sequence to a moving average value sequence as described above is equivalent to performing low-pass filtering, and the waveform represented by the moving average value sequence calculated by Equation (8) is the same as that of the microphone 24L. A waveform is obtained by removing frequency components exceeding the maximum power frequency from the acquired acoustic signal.

  Next, the phase difference calculation unit 404 calculates the time differential value of the moving average value calculated in step S204 for each of the left and right acoustic data sequences, and binarizes the time differential value by its sign (positive / negative). Then, the binarized differential values for the left and right acoustic data are respectively stored in the RAM 42 in time order (S205). This time differential value can be calculated in parallel with the process of step S204 by calculating as a difference obtained by subtracting the previously calculated moving average value from the moving average value calculated this time. The binarized differential value may be, for example, +1 if the calculated time differential value is a positive value and -1 if the calculated time differential value is a negative value.

For example, the binarized differential value BL (i) of the moving average value of the left acoustic data can be defined by the following equation (note that the binarized differential value BR (i of the moving average value of the right acoustic data) ) Can be defined similarly).

Next, the phase difference calculation unit 404 obtains the difference between the rising times at which the left and right binary differential values stored in the RAM 42 have changed from −1 to +1, respectively (S206), and calculates the difference between the latest predetermined number of rising time differences. The average value _Td is calculated as the acoustic phase difference (arrival time difference) in the microphones 24L and 24R (S207), and the process is terminated.

  As described above, the sequence of moving average values stored in the RAM 42 in step S204 represents an acoustic waveform composed of only frequency components equal to or lower than the maximum power frequency, and the change tendency of this waveform is the maximum power frequency component (that is, the maximum amplitude). It is almost determined by the change in the frequency component). Therefore, the extreme position of the time derivative of the moving average almost represents the time when the maximum power frequency component has changed greatly, and the time difference between the extreme positions of the time derivative in the left and right acoustic data is the large change in the acoustic waveform. This represents the difference in time when the part reaches the microphones 24L and 24R, that is, the phase difference.

  For this reason, in this embodiment, as described above, the binarized differential calculation is performed on the waveform after the low-pass filtering based on the moving average value to simplify and extract the change feature of the waveform, and the differential value of the waveform is extracted. The extreme value position is specified as the rising position of the binarized differential value, and the phase difference is calculated.

Next, the sound source direction calculation process (step S3 in FIG. 2) will be described.
FIG. 9 is an explanatory diagram for illustrating a method of specifying the sound source direction in the horizontal plane (XY plane). In FIG. 9, the projection points 60L and 60R representing the positions of the microphones 24L and 24R projected on the XY plane and the reference line 62 connecting the projection points 60L and 60R are used with the artificial movable ear device 1 attached. It is shown with a schematic diagram 64 representing a person's skull.

In FIG. 9, the sound source direction (azimuth angle Ψ _h ) in the horizontal plane is the distance MD _h between the projection points 60L and 60R, the angle MA _{h formed} by the reference line 62 and the y axis, and the phase difference calculation process (FIG. 7). from the phase difference T _d calculated in) it is calculated by the following equation using the speed of sound v _s. The calculated azimuth angle is an angle measured along the direction from the X axis toward the positive direction of the Y axis.

On the other hand, also in the sagittal plane (ZX plane), the sagittal plane connecting the microphone 24L projected on the sagittal plane, and spacing MD _v on sagittal plane 24R, and the projected microphone 24L and 24R From the angle MA _v formed by the upper reference line and the Z axis, the direction of the sound source on the sagittal plane (elevation angle Ψ _v ) is calculated by the following equation. The calculated elevation angle is an angle measured along the direction from the X axis toward the positive direction of the Z axis.

FIG. 10 is a flowchart showing the procedure of the sound source direction calculation process.
First, the sound source direction calculation unit 406 sets these two microphone positions on the horizontal plane (XY plane) based on the three-dimensional position coordinates of the microphones 24L and 24R calculated in the MIC position calculation process (steps S1 and 7 in FIG. 5). projected on (S301), calculates the microphone distance MD _h in the horizontal plane (S302), the reference line 62 connecting between the two microphones in the horizontal plane is calculated the angle MA _h that forms a y-axis (S303).

Then, the sound source direction calculation section 406, two microphones 24L, projecting the three-dimensional position of the 24R on the sagittal plane (ZX plane) (S304), calculates the microphone distance MD _v on the sagittal plane (S305), a reference line connecting between the two microphones calculates an angle MA _v which form the Z-axis on the sagittal plane (S306).

Subsequently, the sound source direction calculation unit 406 calculates an equation based on the MD _h and MA _h calculated in steps S302 and S303 and the phase difference _Td calculated in the phase difference calculation process (step S2 in FIG. 1 and FIG. 8). (11) is used to calculate the sound source direction on the horizontal plane, that is, the azimuth angle Ψ _h (S307). Similarly, based on the MD _v and MA _v calculated in steps S305 and S306, and the phase difference T _d , The sound source direction on the sagittal plane, that is, the elevation angle Ψ _v is calculated (S308), and the process ends.

Next, the MIC direction control process (step S4 in FIG. 5) will be described.
In order to direct the microphone 24 toward the sound source, it is necessary to calculate the rotation angle to be set for the motors 26 and 28 from the azimuth angle Ψ _h and the elevation angle Ψ _v of the sound source.

  In this embodiment, the central axes (z-axis) of the parabolic auricles 4L and 4R are inclined by 45 ° with respect to the Z-axis of the headband 2 (FIG. 1). The rotation planes (xy plane and zx plane) of the microphone 24 by the motors 26 and 28 are also inclined by 45 ° with respect to the horizontal plane (XY plane) and the sagittal plane (ZX plane), respectively.

Therefore, the rotation angles θ ′ _Lh and θ ′ _Rh of the motors 26L and 26R for directing the microphone 24 in the direction of the sound source, and the rotation angles θ ′ _Lv and θ ′ _Rv of the motors 28L and 28R are respectively the azimuth angles Ψ of the sound source. It is expressed using _h and the elevation angle Ψ _v , and is specifically given by the following equation.

FIG. 11 is a flowchart showing the procedure of the MIC direction control process (step S4 in FIG. 5).
First, the MIC direction control unit 408 determines the rotation angle θ ′ _Lh of the motor 26L and the motor 28L based on the azimuth angle Ψ _h and the elevation angle Ψ _v calculated by the sound source direction calculation process (step S3 in FIG. 5, FIG. 10). The rotation angle θ ′ _Lv , the rotation angle θ ′ _Rh of the motor 26R, and the rotation angle θ ′ _Rv of the motor 28R are calculated by equation (12) (S401).

Next, the MIC direction control unit 408 sets each rotation angle to a predetermined number of times s so that the motors 26L, 28L, 26R, and 28R reach the calculated rotation angles in a predetermined time T _s (for example, 200 ms). Divide and change gradually.

That is, the MIC direction control unit 408 obtains the current rotation angle of the motors 26 and 28 acquired in step S101 (FIG. 7) of the MIC position calculation process described above and the target value of each corresponding rotation angle calculated in step S401. Are divided by a predetermined number of times s, and increments Δθ _Lh , Δθ _Lv , Δθ _Rh , Δθ _Rv of each rotation angle to be increased per motor control are calculated (S402). Then, to calculate the divided and the time interval [Delta] T _s a predetermined time _{T s} at a predetermined number of times s (S403), starts the time measurement using the timer 46 (S404).

Next, the MIC direction control unit 408 increases the rotation angle of each motor (26L, 28L, 26R, 28R) by Δθ _Lh , Δθ _Lv , Δθ _Rh , Δθ _Rv each time the time ΔT _s elapses. Each motor is controlled (S405). Subsequently, it is determined whether or not the rotation angle of each motor has reached the target values θ ′ _Lh , θ ′ _Lv , θ ′ _Rh , θ ′ _Rv (S406), and if not (S406, No), step Returning to S405, the process is repeated, and if it has been reached (S406, Yes), the process is terminated.

  With the above processing, the artificial movable ear device 1 accurately calculates the current positions of the two microphones 24L and 24R by kinematics calculation, and calculates the phase difference at the maximum power frequency of the acoustic signals acquired by these two microphones. , By low-pass filtering by moving average calculation and subsequent waveform feature extraction by binarized differential calculation, and by calculating the sound source direction based on the calculated two microphone positions and phase differences, the directions of the two microphones are calculated as described above. Direct to the calculated sound source direction. As described above, since the narrow-band bandpass filtering at the maximum power frequency is not performed in calculating the phase difference, this processing can be easily performed.

  The artificial movable ear device 1 receives the sound from the target sound source more clearly than other sound sources by directing the direction of the microphone toward the sound source (target sound source) that emits the maximum power frequency as described above. As a result, the direction of the target sound source can be accurately identified by repeating the above operation.

  FIG. 12 shows the result of observing the sound source direction specifying operation for the sound source existing in the horizontal plane of the artificial movable ear device 1. 12A shows an observation result when the microphones 24L and 24R are fixed in a certain direction without performing the MIC direction control process, and FIG. 12B shows an observation result when the MIC direction control process is performed. 12A and 12B, the vertical axis represents the direction (azimuth angle) of an actual sound source existing in the horizontal plane, and the horizontal axis represents the sound source direction (azimuth angle) specified by the artificial movable ear device 1. The oblique line is an ideal straight line 70 that indicates a case where the specified sound source direction matches the actual sound source direction, and the observation points are indicated by small circles.

  When the MIC direction control process is not performed (FIG. 12A), there are few observation points on the ideal straight line 70, and the specific error in the sound source direction is large, whereas when the MIC direction control process is performed (FIG. 12B). However, although there are large variations between trials, there are many observation points on the ideal straight line 70, and it can be seen that the specific error in the sound source direction is improved.

  As described above, the artificial movable ear device of the present invention can calculate the sound source direction by a simple process, and repeats the calculation of the sound source direction and the operation of directing the microphone toward the calculated sound source direction. Sound from the sound source can be clearly detected and the direction of the sound source can be specified with high accuracy.

  DESCRIPTION OF SYMBOLS 1 ... Artificial movable ear apparatus, 2 ... Headband, 4, 4L, 4R ... Parabolic pinna, 6 ... Control apparatus, 8 ... Battery, 20 ... Pinna part, 24 ... Microphone, 26, 28 ... Motor, 40 ... CPU, 41 ... ROM, 42 ... RAM, 44 ... AD converter, 46 ... Timer, 48 ... Input / output interface, 402... MIC position calculation unit, 404... Phase difference calculation unit, 406... Sound source direction calculation unit, 408.

Claims (7)

Multiple microphones,
An actuator provided in each of the plurality of microphones to change the direction of the microphone;
Based on the current state of the previous SL actuator, calculates a current position of the microphone, the sound from the sound source obtained by the microphone, said microphone calculating a phase difference between the microphones, which is the calculated The direction of the sound source is calculated based on the distance between the microphones at the current position and the calculated phase difference, and the direction of the microphones is directed to the calculated direction of the sound source. A control device for controlling
With
The control device includes:
The phase difference at the frequency is calculated on the condition that the frequencies having the maximum power included in the sounds acquired from the microphones match each other .
Artificial movable ear device. The artificial movable ear device according to claim 1 ,
The controller is
Perform low-pass filtering to remove frequencies that exceed the frequency with the maximum power from each sound acquired from each microphone,
It is configured to calculate the difference in time when the waveform of each sound after the low-pass filtering is a minimum value as the phase difference,
Artificial movable ear device. The artificial movable ear device according to claim 2 ,
The low-pass filtering is performed by performing a moving average calculation on digital data obtained by converting each sound acquired from each microphone at a predetermined time interval,
Artificial movable ear device. The artificial movable ear device according to any one of claims 1 to 3 ,
The actuator is configured by a motor that rotates the microphones around two axes that intersect at a predetermined angle.
Artificial movable ear device. The artificial movable ear device according to any one of claims 1 to 4 ,
The direction of the sound source is the direction of the sound source projected in the sagittal plane of the wearer wearing the artificial movable ear device , or the direction of the sound source projected in the horizontal plane perpendicular to the sagittal plane.
Artificial movable ear device. Multiple microphones,
An actuator provided in each of the plurality of microphones to change the direction of the microphone;
A control device;
With
The controller is
A device for calculating a current position of the microphone based on a current state of the actuator;
A device for calculating the phase difference between the microphones of the sound from the sound source acquired by the microphone;
A device for calculating the direction of the sound source based on the calculated distance between the microphones at the current position of the microphone and the calculated phase difference;
A device for controlling the actuator so that the direction of each microphone is directed toward the calculated sound source;
Equipped with a,
The device for calculating the phase difference calculates the phase difference at the frequency on the condition that the frequencies having the maximum power included in the sounds acquired from the microphones match each other .
Artificial movable ear device. Calculating the current position of each of the plurality of microphones based on the current state of each actuator that respectively changes the direction of the microphone provided in the plurality of microphones;
Calculating a phase difference between the microphones of the sound from the sound source acquired by the microphone; and
Calculating the direction of the sound source based on the calculated distance between the microphones at the current position of the microphone and the calculated phase difference;
Controlling the actuator so that the direction of each microphone is directed to the calculated direction of the sound source;
Have,
The step of calculating the phase difference calculates the phase difference at the frequency on the condition that the frequencies having the maximum power included in the sounds acquired from the microphones match each other .
A method for identifying the sound source direction.

Images