JPH0129357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a directional microphone device using a microphone array.

(Prior art) Microphones with sharp directional characteristics are constructed using microphone array-type microphones in which a plurality of microphone elements are arranged in a desired arrangement, and outputs from individual microphone elements in a microphone array. Research and development has begun on microphone devices that allow the direction of the main lobe to be changed freely by giving a predetermined amount of time delay to each signal, and recently these devices have been put into practical use. It also began to be attempted.

FIG. 1 is a block diagram showing a configuration example of a microphone device in which the direction of the main lobe can be freely changed by giving a predetermined amount of time delay to each output signal from each microphone element in a microphone array. In FIG _. 1, A ₁ , A ₂ . By arranging them, they constitute a microphone array MA.

The output signals from each microphone element A ₁ , A ₂ ...An are transferred to individual changeover switches SW ₁ , SW ₂ ...
Each microphone element A ₁ , A ₂ ...An
are applied to circuits that apply a predetermined amount of time delay to the output signals from the respective output signals.

The aforementioned changeover switches SW _{1 , SW 2} . ~SWn
The movable contacts a are switched all at once to the fixed contacts l or r labeled with the same reference numerals.

A switching control signal applied via the input terminal 1 causes the movable contacts a in each of the changeover switches SW ₁ to SWn to switch between the respective changeover switches SW ₁ to SWn.
When SWn is switched to the fixed contact l side, the output signal of microphone element A ₁ is sent to output terminal 2 without any delay, and the output signal of microphone element A ₂ is The delay circuit D ₁ delays the time τi and sends it to the output terminal 2, and the output signal of the microphone element A ₃ is sent to the output terminal 2 by the delay circuit D _2.
and the delay circuit _D1 , the signal is sent to the output terminal 2 with a delay of time 2τi applied thereto. Similarly, the output signal from microphone element An-2 is processed by (n-3) delay circuits.
The signal is sent to the output terminal 2 with a time delay of τi, and the output signal from the microphone element An-1 is delayed by (n-2) delay circuits.
2) A time delay of τi is given and sent to the output terminal 2, and the output signal from the microphone element An is further delayed by (n-1) delay circuits.
1) Sent to output terminal 2 with a time delay of τi.

As mentioned above, at predetermined equal intervals d approximately on a straight line
The delay times of each of the delay circuits _D1 , _D2 ...D(n-1) used to delay the output signal from each microphone element arranged in are all set to the same value τi. However, when the delay time τi mentioned above is gradually increased from 0, the direction of the main lobe of the microphone array MA becomes orthogonal to the straight line X-X along which the microphone elements _A1 to An are arranged. Then, from the state facing the front of the microphone array MA (0° state), move to the left along arrow L in the diagram showing the movement mode of the main lobe, which is shown for reference in Figure 1. It gradually changes until it faces 90 degrees.

Next, each changeover switch is controlled by a changeover control signal.
When _the movable contacts a of SW ₁ to SWn are switched to the fixed contacts r side, each microphone element is
The amount of time delay given to the output signals of A ₁ to An is determined by the amount of time delay given to the output signals of the plurality of microphone elements of the microphone array MA when the movable contacts a of the changeover switches SW ₁ to SWn are switched to the fixed contacts l side.
This is different from the amount of time delay given to each output signal of A ₁ to An. That is, the output signal from the microphone element An in this case is sent to the output terminal 2 without delay, and
The output signal of the microphone element An-1 is sent to the output terminal ₂ after being given a time delay of τi by the delay circuit D1, and in the same manner, the output signal of the microphone element An-1 is sent to the output terminal 2 with a time delay of τi given by the delay circuit _D1 . ₂ , the time delay amount given to the output signal of _A1 is 2τi..., (n-3)
τi, (n-2)τi, and (n-1)τi.

Then, in a state where the movable contact a of each changeover switch SW ₁ to SWn is switched to the fixed contact r side, the delay time τi of each delay circuit D ₁ to D(n-1) described above is gradually increased from 0. When the direction of the main lobe of the microphone array MA is changed as follows, the direction of the _main lobe of the microphone array MA is perpendicular to the straight line From the state of °,
The main lobe gradually changes to a state in which it faces 90 degrees to the right along arrow R in the figure showing the movement mode of the main lobe, which is shown for reference in FIG.

Therefore, each changeover switch SW ₁ to SWn is controlled by the changeover control signal supplied via the input terminal.
means for selectively switching the movable contact a to either the fixed contacts l or r, and each delay circuit _D1 to D(n-
By applying 1) the means for varying the delay time τi, the direction of the main lobe of the microphone array MA can be changed as required within a range of 180° in front of the microphone array MA.

FIG. 2 is a block diagram showing an example of the configuration of a delay circuit configured such that delay time is variably controlled. In FIG. 2, Da to Dd indicate respective delay times. τ, 2τ,
4τ, 8τ, and between the input and output terminals of each of the delay circuit elements Da to Dd, individual switches S ₁ , S ₂ , S ₃ ,
S ₄ is connected.

The delay circuit shown in FIG. 2 has each delay circuit element Da
~ Switch S ₁ connected between the input and output terminals of Dd
The 16 combinations of on and off states of ~ _S4 create a delay circuit that exhibits 16 delay times. In other words, when all switches S ₁ to _{S 4} are on, the delay circuit has a delay time of 0.
In addition, when only switch S ₁ is off, the delay circuit has a delay time of τ, and when only switch S ₂ is off, the delay circuit has a delay time of 2τ, and so on. To,
Depending on the on/off combination of switches _S1 to _S4 , the delay time of the delay circuit is 0, τ, 2τ, 3τ, 4τ.
...It can be changed in 16 steps like 15τ.

The ON/OFF control of the four switches _S1 to _S4 described above is easily performed by a delay amount control signal in the form of a 4-bit digital signal applied to the delay circuit via line _l2 . Naturally, if the delay circuit is constructed using a larger number of delay circuit elements than the delay circuit shown in FIG. 2, the number of switchable delay times in the delay circuit can be increased.

Assuming that the delay time τi in each delay circuit _D1 to D(n-1) is changed in 16 steps as described above,
This, in combination with the left and right switching action caused by the switching control signal applied to input terminal 1 via line l ₁ , allows the main lobe of microphone array MA to be oriented within 180° in front of the microphones. It will be changed in the direction of 31.

i.e. via the line l ₁ to the changeover switch SW ₁ ~
A 1-bit switching control signal given to SWn,
The 4-bit delay amount control signal given to the delay circuits _D1 to D(n-1) via the line _l2 is the angle at which the main lobe of the microphone MA is set within a range of 180° in front of the microphone MA. It determines where it will occur.

The switching control signal and delay amount control signal described above are
Generated in the control signal generation circuit CSG,
This control signal generation circuit CSG can easily generate a required control signal if it is configured to include, for example, a microcomputer.

In the example shown in the first diagram, the controller CR is composed of a variable resistor VR and an analog-to-digital converter A/D, and the operator
Microphone array MA by adjusting VR slider
Sets the orientation of the main lobe of.

By adjusting the slider described above, a voltage between the +B voltage and the ground voltage appears on the slider of the variable resistor VR, and the voltage obtained at the slider is applied to the analog-to-digital converter A. /D performs analog-to-digital conversion so that the entire range of voltage change in the slider corresponds to an appropriate value, for example 256, and the analog-to-digital converter A/D outputs the voltage of the slider of the variable resistor VR. An 8-bit main lobe direction indicating signal corresponding to the position is generated and applied to the control signal generating circuit CSG described above.

Now the variable resistor VR in the controller CR
Microphone array
It corresponds to the change range of the direction of the main lobe of the microphone array MA over a range of 180° in front of the MA, and also corresponds to the displacement of the slider of the variable resistor VR over the entire adjustment range. Accordingly, the voltage value appearing on the slider is given to the control signal generation circuit CSG as an 8-bit main lobe direction indication signal by the analog-to-digital converter A/D, and furthermore, the voltage value appearing on the slider is given to the control signal generation circuit CSG as an 8-bit main lobe direction indication signal. Delay circuits _{D1 to} D(n-
In 1), the one-row configuration of the control signal generation circuit CSG will be explained by taking as an example the case where the delay time τi is controlled to be switched in 16 steps by a 4-bit switching control signal. do.

By adjusting the slider of the variable resistor VR of the controller CR, the operator can adjust the microphone array MA.
The direction of _the main lobe is set at the front center of the microphone array MA (orthogonal to the straight line (assuming that the direction of the variable resistor is 0°), the position of the slider of the variable resistor VR in the controller CR is at the center of the range of change of the slider of the variable resistor VR, The numerical value indicated by the output digital signal from the analog-to-digital converter A/D at this time is 128.

By the way, each delay circuit D ₁ to D(n
Since it is necessary to set the delay signal τi in -1) to 0, the microphone array is
In the control signal generation circuit CSG, each of the delay circuits D ₁ to D (n-1)
A 4-bit delay amount control signal that can bring the delay time τi of
A delay amount control signal is generated to turn on all the switches _S1 to _S4 . When the main lobe direction of microphone array MA is 0°,
Since the movable contacts a of the changeover switches SW ₁ to SWn may be connected to either of the fixed contacts l or r,
In this case, the switching control signal may be set so that the movable contact a is switched to a predetermined one of the fixed contacts l and r.

By adjusting the slider of the variable resistor VR of the controller CR, the direction of the main lobe of the microphone array MA can be set within the ranges of 90° to the right from the 0° direction and 90° to the left from the 0° direction. is set. Therefore, if the value indicated by the 8-bit main lobe direction indication signal generated by the analog-to-digital converter A/D corresponding to the adjustment position of the slider of the variable resistor VR of the controller CR is between 1 and 128. For example, if the 8-bit main lobe direction indication signal has a value of 128 to 256, it corresponds to the range from 90° to the left to 0°.
The analog-to-digital converter A/D
For example, if the direction of the main lobe indicated by the numerical value of the 8-bit output digital signal from
Create a switching control signal that switches the movable contacts a of SW ₁ to SWn to the fixed contact l side, and connect it to the wire.
A delay amount control signal is applied to the changeover switches _SW1 to SWn via line _l1 , and a delay amount control signal is generated so that the direction of the main lobe is θ°, and the signal is sent to the delay circuit via line _l2 .
If the direction of the main lobe, which is applied to D ₁ to D(n-1) and is represented by the numerical value of the 8-bit output digital signal from the analog-to-digital converter A/D described above, is, for example, right α°, then the control The signal generation circuit CSG generates a switching control signal such that the movable contacts a of the changeover switches SW ₁ to SWn are switched to the fixed contact r side, and sends the signal to the changeover switches SW _{1 to} SWn via the line l1.
In addition, a delay amount control signal can be created so that the direction of the main lobe is α°, and can be applied to the delay circuits _D1 to D(n-1) via the line _l2 . In the control signal generation circuit CSG, the main lobe sent from the controller CR generates a required switching control signal and a required delay amount control signal based on the direction indication signal, and sends them to the lines l ₁ and l ₂ . It is clear that the main lobe of the microphone array MA is oriented as set by the operator by adjusting the slider of the variable resistor VR of the controller CR.

(Problems to be Solved by the Invention) Now, in the microphone device configured as described above, the main lobe of the microphone device can be set in front of the microphone array MA by adjusting the slider of the variable resistor VR of the controller CR. Although it can be set to point in any desired angular direction within a range of 180°, in the directivity characteristics of the microphone array MA, which is constructed using multiple microphone elements, the main lobe is oriented in the 0° direction, i.e. , the directional characteristics of the microphone array MA when it is configured to face the front of the microphone array MA are as shown in FIG. For example, in the case of a so-called cardioid, as shown in a of FIG. 4, and in the case of a so-called hypercardioid, as shown in a of FIG. becomes.

As is clear from FIG. 3 a and b and FIG. 4 a and b, the main lobe (front lobe) in the microphone array is larger than the main lobe (front lobe) in the microphone element. However, the front lobe of a microphone array becomes increasingly sharp as the number of microphone elements used to construct the microphone array increases.

However, when looking at the front-to-back sensitivity ratio of the microphone array as a whole, it is found that it is the same as the front-to-back sensitivity ratio of the microphone elements used to configure the microphone array.

Also, the direction of the front lobe is
The 0° direction shown in figure b, that is, within the range of 90° to the right (or left) from the front of the microphone array MA {within the range of 90° clockwise (or counterclockwise) from the 0° direction }, the directional characteristics of the microphone array MA change to states as shown in c, d, e in FIG. 3 and c, d, e in FIG. 4.

In other words, when the direction of the main lobe of the microphone array MA is tilted in the 0° direction, that is, in the clockwise (or counterclockwise) direction from the front of the microphone array MA, the line 90° −
A rear lobe is generated at a mirror-symmetrical position about 270°.

The above-mentioned main lobe (front lobe) and rear lobe are the directional characteristic curves (indicated by dotted lines in b to e in Figure 3 and b to e in Figure 4) of the microphone elements constituting the microphone array MA. (as shown).

As mentioned above, when the direction of the main lobe (front lobe) in the microphone array is changed from 0° clockwise (or counterclockwise) within a range of 90°, the arrangement of the microphone elements in the microphone array changes. A rear lobe is generated at a mirror-symmetrical position with respect to the direction, but the signal generated in response to the sound absorbed by this rear lobe is also included in the output signal of the microphone, so in a directional microphone device. , the occurrence of a posterior lobe is not desirable;
There was a desire to realize a directional microphone device that does not generate backward lobes.

(Means for Solving the Problems) The present invention provides a directional microphone device configured such that the direction of the main lobe (front lobe) of a microphone array can be changed within a required range in front of the microphone array. 1 so that the rear lobe of the microphone array, which occurs at a mirror-symmetrical position with the main lobe (front lobe) of the microphone array, occurs in the insensitive part of the directivity of the microphone elements used to configure the microphone array. The directivity characteristics of a microphone element configured by a pair of pressure type microphones and one velocity type microphone are changed in accordance with a change in the direction of the main lobe (front lobe) of the microphone array, The rear lobe in the microphone array is eliminated.

(Embodiment) FIG. 5 is a block diagram of an embodiment of the directional microphone device of the present invention, and in FIG. 5, the components corresponding to the components in the microphone device shown in FIG. , the same drawing symbols as those used in FIG. 1 are used.

In FIG. 5, MA is a microphone array, and this microphone array MA is constructed by arranging unit microphone elements A ₁ , A ₂ . . . An in a desired arrangement manner. The microphone elements A ₁ , A ₂ ...An of each unit used in the configuration of the microphone array MA are respectively,
One pressure type microphone (one each of A ₁ p, A ₂ p...Ap with the subscript P in the figure,
Each unit of microphone element A ₁ , A ₂ ...An is a single pressure type microphone, but in the following description, when explaining matters common to each unit of microphone element, pressure is used. type microphone Ap) and, respectively,
One speed type microphone (one each of A ₁ v, A ₂ v...Anv with subscript V in the figure,
The individual unit microphone elements A ₁ , A ₂ ...An is one speed type microphone, but in the following description, when explaining matters common to each unit microphone element, the speed type microphone Av) and a signal level variable adjustment means (VL ₁ p, VL ₂ p) that variably adjusts the signal level of the output signal from the pressure type microphone.
...Vlnp is a variable adjustment means for the signal level of the output signal from the pressure type microphone in the microphone elements A ₁ , A ₂ ...An in each unit, but in the following description, each unit's When explaining things common to microphone elements, it is described as variable signal level adjustment means VLp)
and a signal level variable adjustment means (VL ₁ v, VL ₂ v...VLnv) for variably adjusting the signal level of the output signal from the velocity microphone, each of which is connected to the microphone element A ₁ , A of each unit. ₂ ...An variable adjustment means for the signal level of the output signal from the speed type microphone, but in the following description, when explaining matters common to each unit of microphone element, the variable adjustment means for the signal level VLv ) and signal synthesis means (SC ₁ , SC ₂ ,
...SCn is a means of combining signals in the microphone elements A ₁ , A ₂ ...An of each unit, but in the following description, when explaining matters common to the microphone elements of each unit, is composed of a signal synthesizing means SC) and the like. In the following description, matters common to each unit of microphone elements A ₁ , A ₂ . . . An are described in the same way as the unit of microphone element A.

In FIG. 5, the X-X line shown in the microphone array MA section indicates the unit microphone elements constituting the microphone array MA.
A ₁ , A ₂ ...A line indicating the direction of the An array, and the 0° mark written on the front part of the microphone array MA indicates the front direction of the microphone array MA. further right
The 90° and 90° left indications indicate directions of 90° clockwise and 90° counterclockwise from the 0° direction showing the front of the microphone array MA described above.

In FIG. 5, the pressure type microphone Ap and the velocity type microphone Av in the unit microphone element A are shown as being lined up in the X-X direction in the figure, but in the microphone array MA, The direction of the front lobe,
In a directional microphone device that can be changed in a required angle range in front of a microphone array MA, a pressure type microphone Ap and a velocity type microphone Av are arranged in the direction of X-X as shown in Figure 5.
The arrangement may be such that the pressure microphone Ap and the velocity microphone Av are lined up in a linear manner, compared to the wavelength of the highest frequency sound in the frequency range handled by the directional microphone device. This only applies when the dimension in the X-X direction of
The pressure type microphone Ap and the velocity type microphone Av in the diagram are required to be arranged in such a manner that they are stacked in a direction perpendicular to the plane of the paper at a specific position in the direction of the X-X line in the figure. Ru.

The microphone elements A ₁ , A ₂ . . . An of each unit constituting the microphone array MA are arranged so that the microphone elements of each unit are arranged in a straight line on the same plane at a predetermined interval, or Alternatively, the microphone elements of each unit are arranged on a circular arc on the same plane at a predetermined interval, or the microphone elements of each unit are arranged on a broken line on the same plane at a predetermined interval. However, if the microphone elements of each unit are arranged on a circular arc or on a broken line, the direction of the main lobe of the microphone array MA is aligned with the front of the microphone array MA. This is effective in preventing the directivity characteristics at high frequencies from becoming too sharp even when the direction is set at a large angle.

The mutual spacing d between the microphone elements A ₁ , A ₂ . . . An in each unit is d<λ /2
is determined to satisfy the relationship.

Since all of the n units of microphone elements A ₁ to An constituting the microphone array MA have the same configuration, it is difficult to distinguish between the individual units of microphone elements A ₁ to An. Without doing this, we can use the expression method mentioned above, namely,
Unit microphone element A, pressure type microphone
The configuration and operation of the unit microphone element will be explained using expressions such as Ap, speed type microphone Av, signal level variable adjustment means VLp and VLv, and signal synthesis means SC.

In the pressure type microphone Ap and the velocity type microphone Av used in the configuration of the unit microphone element A, the pressure type microphone Ap has an omnidirectional (omnidirectional) directivity characteristic as shown in a in Fig. 6. It also has a speed type microphone.
Av has a so-called figure-8 bidirectional directivity characteristic as shown in e of FIG.

Then, in the unit microphone element A,
The output signal of the pressure type microphone Ap is given to the signal synthesis means SC after its signal level is adjusted by the variable signal level adjustment means VLp, and the output signal of the velocity type microphone Av is adjusted in signal level by the variable signal level adjustment means VLp. Since the signal level is adjusted by the adjustment means VLv and then given to the signal synthesis means SC, the directivity characteristic of the unit microphone element A is the same as that of the pressure type microphone Ap by the signal level variable adjustment means VLp and VLv. It changes depending on how the signal level of the output signal and the signal level of the output signal of the velocity microphone Av are adjusted.

For example, the signal level variable adjustment means VLp,
By adjusting VLv, the output signal of the pressure microphone Ap is directly converted to the signal synthesis means SC.
At the same time, the output signal of the velocity microphone Av is
When SC is not applied, the directivity characteristic of unit microphone element A is a in Figure 6.
For example, contrary to the above case, a means for variable adjustment of the signal level is provided.
By adjusting VLp and VLv, the output signal of the voltage type microphone Ap is prevented from being applied to the signal synthesis means SC, and the output signal of the velocity type microphone Av is prevented from being applied as it is to the signal synthesis means SC. SC, the directional characteristic of the unit microphone element A is the 6th one.
Figure 8 shows bidirectionality as shown in e of the figure, and furthermore, for example, the signal level variable adjustment means VLp
When the output signal of the pressure microphone Ap and the output signal of the velocity microphone Av are combined in a 1:1 ratio by adjusting VLv, the directivity of the unit microphone element A becomes as shown in Figure 6b. It becomes a cardioid type unidirectional, and so on.
The directivity characteristics of the unit microphone element A are determined by adjusting the signal level of the output signal of the pressure type microphone Ap using variable signal level adjusting means VLp and VLv,
Depending on how the signal level of the output signal of the velocity microphone Av is adjusted,
From omnidirectional as shown in Figure 6 a to cardioid unidirectional as shown in Figure 6 b,
It changes to figure 8-shaped bidirectionality as shown in the figure e. 6A to 6E illustrate and explain the manner in which the directivity characteristics change in the unit microphone element A that occurs as described above.

Looking at the directional characteristic curve of the unit microphone element A shown in a to e in FIG.
For the omnidirectional pattern shown in
Naturally, there is no insensitive region, but as can be seen from the directional characteristic curves shown in b to e in Fig. 6, from the 180° direction in b in Fig. 6, To the direction of 90°-270° at e,
The angular position of the insensitive portion of the unit microphone element A changes as the directivity characteristics of the unit microphone element A change.

Therefore, in the directional microphone device of the present invention, the spatial position of the microphone array is kept constant by giving a predetermined amount of time delay to each output signal from the unit microphone elements _A1 to An constituting the microphone array. When the direction of the front lobe in the microphone array is freely changed within a predetermined range in front of the microphone array, the rear lobe, which occurs at a position mirror-symmetrical to the front lobe, becomes the direction of the insensitivity in the directional characteristic curve. The directional characteristics of the unit microphone elements A ₁ to An are changed so that the rear lobe is eliminated so that the signal level at the unit microphone element A Variable adjustment of the signal level of the output signal of the pressure type microphone Ap and the signal level of the output signal of the velocity type microphone Av by the variable adjustment means VLp and VLv of the microphone array MA is performed in accordance with the direction of the front lobe of the microphone array MA. is being done.

In the directional microphone device according to an embodiment of the present invention shown in FIG. 5, a controller CR, a control signal generation circuit CSG, delay circuits _D1 to D(n-1),
The components such as the changeover switches SW ₁ to SWn and the lines l ₁ and l ₂ are the same as those in the microphone device shown in the first diagram, and the operator can switch the slider of the variable resistor VR of the controller CR. When the direction of the main lobe of microphone array MA is set by adjusting Given.

The control signal generation circuit CSG generates a switching control signal and a delay amount control signal in the same manner as in the case of the microphone device shown in Figure 1, and the switching control signal is
Changeover switches SW ₁ to SWn are given via l ₁ ,
Also, the delay amount control signal is sent to the delay circuit _D1 via the line _L2 .
~D(n-1).

As is clear from the above, the delay amount control signal generated from the control signal generation circuit CSG is
The direction of the front lobe of microphone array MA is
Front front of microphone array MA (0° direction)
Since the directional microphone device shown in FIG. 5 includes information on the degree of angle clockwise or counterclockwise from Using the angle information, the unit microphone element A exhibits the required directivity characteristic, that is,
A signal is obtained to configure a unit microphone element A that exhibits a directivity characteristic such that the rear lobe, which occurs at a position mirror-symmetrical to the front lobe, is located in an insensitive portion.

In other words, as mentioned above, the rear lobe of microphone array MA appears at a mirror-symmetrical position with the front lobe of microphone array MA, so the angle information of the front lobe of microphone array MA that the delay amount control signal has It is easy to predict the position where the rear lobe of the microphone array MA will occur based on To do this, the output signal of the pressure microphone Ap and the output signal of the velocity microphone Av must be
Since it is known in advance what signal level each should be, based on the delay amount control signal sent from the control signal generation circuit CSG via line _l2 , variable adjustment means VLp in the unit microphone element A;
It is easy to create a signal level adjustment control signal to be applied to VLv, and in the embodiment shown in FIG. Microphone element A ₁ of each unit via wires l ₄ and l ₅
Variable adjustment means at ~An VL ₁ p ~ VLnP, VL ₁ v
~ I am trying to give it to VLnv.

The aforementioned variable adjustment means VL ₁ p ~ VLnp, VL ₁ v ~
As the VLnv, a so-called electronic volume composed of semiconductor elements is used so that the signal level can be variably adjusted by inputting a signal level adjustment control signal in the form of a digital signal with the required number of bits. In addition, an adder or a subtracter is used as the signal combining means SC.

Use an adder as the signal synthesis means SC, or
Alternatively, whether a subtractor is used depends on whether the output signal of the pressure microphone Ap and the output signal of the velocity microphone Av are in phase or out of phase.

The directional microphone device of the present invention has a microphone array MA by operating a controller CR.
When changing the direction of the front lobe of the microphone array within a range of 90° clockwise and counterclockwise from the front of the microphone array (0° direction),
The insensitive portion of the directivity characteristic of the unit microphone element A used to configure the microphone array MA corresponds to the position of the rear lobe that is mirror-symmetrical to the front lobe. It is clear that by changing the directivity characteristics of the unit microphone element, the rear lobe in the microphone array MA can be effectively eliminated, so the above-mentioned problem can be solved. clockwise or counterclockwise from the front of the microphone array MA (0° direction).
When the angle is changed to nearly 90°, the front lobe and rear lobe of the microphone array MA will overlap, so the insensitive part of the directivity of the unit microphone element will be canceled so that the rear lobe will be canceled even in this state. If the generation position of the rear lobe of the microphone array MA is made to coincide with the generation position of the rear lobe of the microphone array MA, the rear lobe of the microphone array MA and the front lobe that overlaps with it will be erased.

And, as mentioned above, the microphone array
Since the rear lobe in the state where the front lobe and the rear lobe in MA overlap are the same as the front lobe, there is no need to eliminate the rear lobe in such a case.

Therefore, when the direction of the front lobe in the microphone array MA is oriented in a range close to 90 degrees clockwise and counterclockwise from the front front (0 degree direction) of the microphone array, The adjustment control signal is generated from the adjustment control signal generation circuit CU at a signal level such that the resulting rear lobe is not canceled. This means that the direction of the front lobe of the microphone array can be changed.

(Effects) As is clear from the above detailed explanation, the directional microphone device of the present invention is a unit microphone element used in the configuration of a microphone array, and is capable of transmitting output signals of a pressure microphone and a velocity microphone. By using a configuration in which the directivity characteristics can be varied by varying the mixing ratio, the direction of the front lobe of the microphone array can be changed over a required range in front of the microphone array. The rear lobe that occurs at a position that is mirror-symmetrical to the front lobe is eliminated by changing the directivity characteristics of the unit microphone element so that the position where the rear lobe occurs becomes an insensitive part of the unit microphone element. Therefore, according to the device of the present invention, the above-mentioned conventional problems can be satisfactorily solved, and the front lobe of the microphone array can be oriented clockwise from the front front (0° direction) of the microphone array.
Or, when the angle is approximately 90 degrees counterclockwise, the rear lobe is not erased,
The direction of the front lobe in the microphone array MA can be changed over a range of 180 degrees in front of the microphone array.

[Brief explanation of drawings]

Figure 1 is a block diagram of the microphone device, Figure 2
This figure is a block diagram of an example of the configuration of a delay circuit, FIGS. 3, 4, and 6 are directional characteristic curve diagrams, and FIG. 5 is a block diagram of an embodiment of the directional microphone device of the present invention. A ₁ ~An...unit microphone element, A ₁ p~
Anp...Pressure type microphone, A ₁ v~ Anv...Velocity type microphone, VL ₁ p~VLnp, VL ₁ v~
VLnv...Signal level variable adjustment means, SC ₁ ~
SCn... Signal synthesis means, CU... Signal level adjustment control signal generation circuit, CSG... Control signal generation circuit, SW ₁ to SWn... Changeover switch, D ₁ to D
(n-1)...delay circuit, CR...controller,
l ₁ ~ l ₅ ... line.

Claims (1)

[Scope of Claims] 1. For each unit microphone element in a microphone array formed by arranging a plurality of unit microphone elements formed by pairing one pressure type microphone and one velocity type microphone, ,
The output signal from one pressure-type microphone and the output signal from one velocity-type microphone constituting a unit microphone element are individually adjusted to a predetermined level. a means for obtaining an output signal of a unit microphone element by combining the signal levels through a variable adjustment means which is adapted to be able to change the signal level; and an output signal from each unit microphone element as described above. By giving each signal a predetermined amount of time delay, the spatial position of the microphone array remains constant, and the direction of the front lobe in the microphone array can be freely changed within a predetermined range in front of the microphone array. and the above-mentioned means so that the generation position of the rear lobe generated at the rear of the microphone array corresponds to the change in the direction of the front lobe of the microphone array described above is made into an insensitive area in the unit microphone element described above. A directional microphone device comprising means for variably adjusting the signal level of an output signal of a pressure type microphone and the signal level of an output signal of a velocity type microphone by means of a variable signal level adjustment means. . 2. Construct a unit microphone element for each unit microphone element in a microphone array formed by arranging a plurality of unit microphone elements configured by pairing one pressure type microphone and one velocity type microphone. The signal level of each of the output signals from one pressure type microphone and one velocity type microphone can be individually changed in a predetermined manner. means for synthesizing the output signals of the unit microphone elements through a signal level variable adjustment means configured as described above; By applying a fixed amount of time delay, the spatial position of the microphone array remains constant, and the orientation of the front lobe at the microphone array is changed clockwise from this 0 degree direction, with the direction in front of the microphone array being 0 degrees. and counterclockwise, respectively, within a range of approximately 90 degrees, and means for allowing the rear lobe to occur at the rear of the microphone array in response to the aforementioned change in the direction of the front lobe of the microphone array. The rear lobe, excluding the rear lobe that occurs behind the microphone array, when the front lobe of the microphone array is oriented approximately 90 degrees counterclockwise from the 0 degree direction in front of the microphone array. The above-mentioned signal level variable adjustment means adjusts the signal level of the output signal of the pressure-type microphone and that of the velocity-type microphone so that the lobe generation position is in the insensitive region of the unit microphone element. and means for variably adjusting the signal level of the output signal.