JPH07240990A - Microphone device - Google Patents

Abstract

PURPOSE:To provide ultra sharps direction characteristics with a small-sized constitution. CONSTITUTION:A microphone part 1 is composed of plural microphones M1, M2 and M3 provided with mutually different directional characteristics to a prescribed spindle. An energy calculation part 2 segments the output signals of the microphones M1, M2 and M. by windows provided with a fixed length at all times and calculates the total sum of energy in the segmented section. A comparator 3 compares the energy of the microphones M1, M2 and M3 calculated in the segmented window section by the energy calculation part 2 and supplies information indicating which microphone is provided with the minimum energy to a changeover switch 4. A changeover switch part 4 outputs the output signals of one of the three microphones M1, M2 and M3 provided with the minimum energy in the segmented window section from an output terminal 5 corresponding to the information supplied from the comparator 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microphone device capable of obtaining super directional characteristics.

[0002]

2. Description of the Related Art Microphones have directional characteristics. The directional characteristic is a characteristic indicating the relationship between the direction viewed from the microphone and the sensitivity, and there are mainly three types of omnidirectional, unidirectional, and bidirectional.

An omnidirectional microphone is capable of picking up sound with almost uniform sensitivity in all directions, and is used for recording the atmosphere of a venue or picking up unspecified sound regardless of the direction. Are suitable.

A unidirectional microphone has the highest sensitivity on the front side, and the sensitivity decreases from the left to the right. It is suitable for recording vocals and the sound of specific musical instruments, as it can accurately capture the target sound. Also, when used for stereo recording, the left and right sounds can be well separated and collected, so the sound image can be easily determined.

The bidirectional microphone has a figure-8 directional characteristic that is sensitive to the front and back, and is used in a special case or when the phase is reversed with respect to the back surface. It is used as a combination microphone device that can combine directional characteristics with a directional microphone.

The above unidirectional microphone has sufficient sensitivity in the front direction, that is, in the forward direction, which is the desired direction, while the sensitivity in other directions is low. Attenuation of, for example, 6 dB is applied to the sound in the direction of 90 ° from the front. On the other hand, a microphone in which the degree of attenuation is further increased and the sensitivity sharply decreases when the incident angle of sound deviates from the axial direction is called a sharp directional microphone. As the sharp directivity microphone, there are a hyper cardio type microphone and a super cardio type microphone.
These sharply directional microphones are used, for example, in a camera-integrated VTR to collect only sound in the direction of the subject.

[0007]

By the way, in recent years, for example, in a camera-integrated VTR using the above-mentioned sharp directivity microphone, it is desired to obtain a sharper directivity characteristic (hereinafter referred to as super directivity). ing. It is also desired to obtain this superdirectivity in the two LR channel directions.

To obtain superdirectivity using conventional techniques,
As is known for gun microphones, a very large configuration is essential, and a small camera-integrated VT used for consumer use.
Not suitable for R. Further, two gun microphones are required to obtain superdirectivity in the two channel directions of the LR, which further hinders downsizing.

The present invention has been made in view of the above circumstances, and a microphone device that can obtain superdirectivity with a small structure and a microphone device that can obtain two-channel superdirectivity with a small structure. For the purpose of providing.

[0010]

A microphone device according to the present invention comprises a microphone means having a plurality of different directivity characteristics, a level detecting means for detecting the level of each output signal of the microphone means, and the level detecting means. Comparing means for comparing the levels of the respective output signals detected by, and selecting means for selecting and outputting one of the output signals having the smallest output signal level in accordance with the result of the comparison by the comparing means. The above problem is solved by having

In this case, it is preferable that the microphone means has a plurality of directional characteristics with respect to a predetermined main axis. The microphone means may be composed of a plurality of microphone units having different directivity characteristics with respect to a predetermined main axis.

The microphone means may obtain a plurality of directional characteristic outputs by appropriately mixing outputs of at least two microphone units having different directional characteristics.

Further, the above-mentioned microphone means may obtain directional characteristics of two independent channels in the main axis direction by using two unidirectional microphone units and one omnidirectional microphone unit. Good.

Further, the level detecting means may cut out each output signal corresponding to each of the directional characteristics of the microphone means at any time with a window having a constant length, and calculate the total energy in the cut-out section. In this case, the windows used include various windows such as a directional window, a Hanning window, and a Hamming window. Then, the comparing means compares the total energy of the cutout sections, and the selecting means selects and outputs one of the output signals having the smallest output signal level according to the comparison result of the comparing means. .

[0015]

The comparing means compares the levels of the respective output signals of the microphone means detected by the level detecting means in the cut-out section of a constant length, and the selecting means outputs the respective output signals having the smallest output signal levels according to the result of the comparison. Since one of the signals is selected and output, it is possible to output the voice with the least noise from directions other than the desired direction for each cut-out section of the above-mentioned fixed length, and thus obtain with the conventional directional microphone. It is possible to obtain superdirectivity, which was not possible with a very small configuration.

[0016]

Embodiments of the microphone device according to the present invention will be described below. First, the first embodiment will be described with reference to FIGS. In the first embodiment, as shown in FIG. 1, a microphone section 1 having a plurality of different directional characteristics, an energy calculation section 2 for calculating the energy of each output signal of the microphone section 1, and this energy calculation section. 2 selects one of the outputs of the microphone unit 1 having the smallest output signal level according to the comparison by the comparator 3 for comparing the levels of the output signals calculated by A microphone device having a changeover switch section 4 for outputting only an output signal from an output terminal 5.

The microphone unit 1 is composed of a plurality of microphones M ₁ , M ₂ ... M _n having different directivity characteristics with respect to a predetermined main axis. For example, a specific example of the microphone device of the first embodiment when the microphone unit 1 is composed of three kinds of microphones M ₁ , M ₂ and M ₃ as shown in FIG. 2 will be described below. . It should be noted that each part except the microphone part 1 in FIG. 2 is the same as each part in FIG.

In FIG. 2, the microphone of the microphone unit 1
Rohon M₁Is the polar pattern Pa as shown in FIG.
It is a bidirectional microphone that has. This bidirectional microphone
Rohon M₁Shows the front and back as indicated by the polar pattern Pa.
And both have sensitivity 1 in the rear and sensitivity 0 in the lateral direction.
It has a directional characteristic of the next 8 type. Also, the microphone M
₂Has a polar pattern Pb, for example cardioid
Directional microphone M such as a microphone₂And
It This sharp directional microphone has a polar pattern Pb.
, The sensitivity is 1 in the front and about 0.
4 or less and the sensitivity in the lateral direction is about 0.3 or less
Has directional characteristics. Also, the microphone M ₃Is Paula
Unidirectional microphone M with turn Pb₃Is.
This unidirectional microphone has a polar pattern Pc
As shown, the sensitivity is 1 at the front and 0 at the back.
However, it has a directional characteristic with a sensitivity of 0.5 in the lateral direction.
One.

The energy calculation unit 2 cuts out the output signals of these three types of microphones M ₁ , M ₂ and M ₃ at any time with a window having a fixed length, and calculates the total energy in the cut-out section. ing. This total energy is the sum of all squared values of each data sample in the cutout section. As the window used in this case, various windows such as a rectangular window, a Hanning window and a Hamming window can be used. The window length is a very short time, for example, about 42 msec.

The comparator 3 includes three types of microphones M ₁ calculated by the energy calculation unit 2 in a cutout window section having a constant length,
The energies of M ₂ and M ₃ are compared, and information on which microphone has the smallest energy is supplied to the changeover switch 4.

The changeover switch unit 4 responds to the above information supplied from the comparator 3 and has three types of microphones M having the smallest energy in the cutout window section.
One of the output signals of ₁ , M ₂ and M ₃ is output from the output terminal 5.

Here, the changeover switch unit 4 selects the output signal having the smallest energy as follows. In FIG. 3, the sensitivity in the front direction of each of the microphones M ₁ , M ₂ and M ₃ is 1 as described above. Therefore, the energy of each microphone output with respect to the desired sound from the front direction is almost the same. Here, considering that noise enters from the rear, for example, the bidirectional microphone M ₁ of the polar pattern Pa has sensitivity 1 in the rear as well, and therefore outputs an output signal having high energy. Become. That is, the desired voice containing a lot of noise is output. In this case, the unidirectional microphone M having the polar pattern Pc
_{Since 3} has no directivity toward the rear, it has an output signal with the smallest total energy. Similarly, considering the noises coming from the lateral direction or the diagonal direction, the output signals of the microphones that minimize the energy of each noise may be selected.

That is, as shown in FIG. 4, a specific example of the microphone device of the first embodiment is a polar pattern P.
bidirectional microphone M ₁ of a, sharp directional microphones M ₂ of polar pattern Pb, rather than using polar pattern Pc of the unidirectional microphone M ₃ each alone can reduce the number of noise. In FIG. 4, a female voice comes from a desired direction (front side shown in FIG. 3), while side and rear sides (horizontal side and rear side shown in FIG. 3) as noise component voices.
3 shows noise reduction amounts in directions other than the desired direction, that is, the lateral direction and the backward direction, when different female voices and male voices respectively arrive from. For example, in FIG. 3, when noise enters from the rear at an angle of 180 °, the noise is reduced by selecting the output signal of the unidirectional microphone M ₃ of the polar pattern Pc. It is possible to output only the desired voice in the desired direction (front direction) at the angle of 0 ° shown in (3). Also, for example, in FIG.
In the case where noise enters from the horizontal direction at an angle of 90 °, the desired signal with reduced noise is output by selecting the output signal of the bidirectional microphone M ₁ of the polar pattern Pb. You can

Therefore, the microphone device according to the first embodiment can output the sound with the least noise from directions other than the desired direction for each cut-out section of the above-mentioned fixed length, thus obtaining superdirectivity. be able to.

Next, a second embodiment will be described with reference to FIG. In the second embodiment, several types of directional characteristic outputs are calculated using two microphone outputs, an omnidirectional microphone M ₁₁ and a unidirectional microphone M ₁₂ , and the levels of these directional characteristic outputs are calculated. The comparator 15 compares the level output calculated by the energy calculating unit 14 which is a level detecting unit, and the level output calculated by the energy calculating unit 14, and the comparison result by the comparator 15, that is, the above several types having the smallest level output Changeover switch section 16 selects one of the directional characteristic outputs of the
Output from. Here, the omnidirectional microphone M ₁₁ and the unidirectional microphone M ₁₂ are arranged with their main axes aligned.

Here, as described above, the two directional characteristics,
For example, the principle of obtaining several types of directional characteristics from non-directional characteristics and unidirectional characteristics will be described.

The directional characteristic of the microphone of the primary sound pressure gradient is

[0028]

[Equation 1]

It can be expressed as Here, θ represents the incident angle of sound, and the polar pattern of the directional characteristic can be drawn from the equation (1).

Table 1 shows the general omnidirectional, unidirectional, bidirectional, and sharp (super) directional characteristics that can be obtained by the above equation (1).

[0031]

[Table 1]

As described above, each directional characteristic can be freely generated by changing the combination of the values of the coefficients α and β in the above equation (1).

In practice, as shown in FIG. 5, the multiplier 11
_1, 11 ₂ at · · · 11 _n, multiplied by the non-directional input multiplier coefficients a _1, a ₂ ··· a _n to the output of the omnidirectional microphones M _11, the multiplier 12 _1, 12 _2, ... 12 _n , the output of the unidirectional microphone M ₁₂ is multiplied by the unidirectional input multiplication coefficients b ₁ , b ₂ ... b _n , and the respective multiplication values are added by adders 13 ₁ , 13 ₂ , ... 13 _{n are} added to obtain the above various characteristic outputs.

When the directional characteristics of omnidirectionality, unidirectionality, bidirectionality, and superdirectivity are actually obtained by using the configuration of such a multiplier and an adder, the microphones M ₁₁ and Table 2 shows specific values of each multiplication coefficient by which the two inputs from M ₁₂ are multiplied.

[0035]

[Table 2]

Energy calculator 1 which is a level detector
4, the comparator 15 and the changeover switch 16,
Since it is the same as each part of the first embodiment, the description is omitted here.

As described above, in the microphone device according to the second embodiment, several kinds of directional characteristic outputs are calculated from the omnidirectional microphone M ₁₁ and the unidirectional microphone M _12, and these directional characteristics are calculated. The energy level is calculated by the energy calculating section 14 which is a level detecting section, and the level output calculated by the energy calculating section 14 is compared by the comparator 15.
The changeover switch 16 selects a comparison result of the comparator 15, that is, one of the above-mentioned directional characteristic outputs having the smallest level output, and outputs only the output signal thereof.
Since it outputs from each direction, the voice with the most noise from directions other than the desired direction can be output for each cut-out section of the above-mentioned fixed length, and thus super-directivity that cannot be obtained with conventional directional microphones. Can be obtained in a very compact configuration.

Next, a third embodiment will be described with reference to FIG. In the third embodiment, one omnidirectional microphone M ₂₁ and two unidirectional microphones M ₂₁ are used.
₂₂ and M ₂₃ are microphone devices for obtaining super-directivity of two channels which are oriented independently of the main axis.

The outputs of the omnidirectional microphone M ₂₁ are the multipliers 21 ₁ , 21 ₂ ... 21 _n and the multipliers 31 ₁ , 31 _2.
.. 31 _n are supplied. Unidirectional microphone M ₂₂
The output of is supplied to the multipliers 22 ₁ , 22 ₂ ... 22 _n . On the other hand, the output of the unidirectional microphone M ₂₃ is supplied to the multipliers 32 ₁ , 32 _2, ... 32 _n .

The output of the omnidirectional microphone M ₂₁ multiplied by the omnidirectional input multiplication coefficients a ₁ , a ₂ ... A _n in the multipliers 21 ₁ , 21 ₂ ... 21 _n and the multiplier 22 ₁ , 22 ₂ , ...
Unidirectional input multiplier coefficient at _{·· 22 n b 1, b 2} ··· b n
The output of the unidirectional microphone M ₂₂ multiplied by is supplied to the adders 23 ₁ , 23 _2, ... 23 _n and added,
Each addition output is supplied to the energy calculation unit 24 and the changeover switch unit 26. On the other hand, the multipliers 31 ₁ and 31 ₂
Omnidirectional input multiplier at · · · 31 _n coefficients c _1, c ₂ ··· c _n
There the output of the omnidirectional microphones M ₂₁ multiplied, the multiplier 32 _1, 32 _2, unidirectional input multiplier coefficient d ₁ at _{··· 32 n, d 2 ··· d} n is multiplied single The outputs of the unidirectional microphone M ₂₃ are supplied to the adders 33 ₁ , 33 _2, ... 33 _n and added, and the respective addition outputs are supplied to the energy calculation unit 34 and the changeover switch unit 36.

Therefore, in the third embodiment, two are used so that the configuration of the second embodiment can be applied to the stereo RL.

In this third embodiment, one omnidirectional microphone M ₂₁ and two unidirectional microphones M ₂₂ and M ₂₃ are arranged as shown in FIG. The unidirectional microphone M ₂₂ is arranged with its main axis oriented in the 45 ° right direction, and the unidirectional microphone M ₂₃ is arranged with its main axis oriented in the 45 ° left direction.

Energy calculator 24 which is a level detector
And 34, the comparators 25 and 35, and the change-over switches 26 and 36 are the same as those in the second embodiment, and the description thereof is omitted here.

In the microphone device of the third embodiment,
Several kinds of directional characteristic outputs are calculated from the omnidirectional microphone M ₂₁ and the unidirectional microphone M _22, and the levels of these directional characteristic outputs are calculated by the energy calculating section 24 which is a level detecting section. The comparator 25 is caused to compare the level output calculated by the energy calculating section 24, and the comparator 2
5, the changeover switch 26 selects one of the above-mentioned directional characteristic outputs having the smallest level output, and outputs only the output signal from the output terminal 27 to obtain several types in the stereo R direction. It is possible to obtain the directional characteristic output of. On the other hand, in the microphone device of the third embodiment, several kinds of directional characteristic outputs are calculated from the omnidirectional microphone M ₂₁ and the unidirectional microphone M _23, and the levels of these directional characteristic outputs are set to levels. The level output calculated by the energy calculating unit 34, which is a detecting unit, is compared by the comparator 35, and the comparison result by the comparator 35, that is, the above-mentioned several types having the smallest level output. Switch 3 for selecting one of directional output
6 selects and outputs only the output signal from the output terminal 37 to obtain several types of directional characteristic outputs in the stereo L direction.

FIG. 8 shows three types of microphones having a principal axis in the right 45 ° direction obtained by the omnidirectional microphone M ₂₁ and the unidirectional microphone M ₂₂ of the microphone device of the third embodiment, that is, , Directional characteristics indicated by the polar pattern Pa, super directivity indicated by the polar pattern Pb, and unidirectional characteristics indicated by the polar pattern Pc.
The three types of directional characteristics are the omnidirectional input multiplication coefficients a ₁ , a ₂ ... A _n and the unidirectional input multiplication coefficient b ₁ ,
It is obtained by setting b ₂ ... b _n as shown in Table 2 above. Similarly, in the third embodiment, it is possible to obtain three types of directional characteristics having the principal axis in the left 45 degree direction by using the omnidirectional microphone M ₂₁ and the unidirectional microphone M _23. it can. As described above, in the third embodiment, it is possible to obtain the super directivity characteristics of two channels with a compact structure.

The microphone device according to the present invention is
The present invention is not limited to the first to third embodiments described above. For example, the comparator may compare not only the total energy of the output signals but also the amplitudes, peak values, etc. of the output signals. The level detecting means may detect the level of each output signal instantaneously.

The microphone device described above is not only used as a sound pickup microphone device of a camera-integrated VTR, but also applicable to all microphone devices such as a commercial video camera and a measurement microphone device.

[0048]

The microphone device according to the present invention has microphone means having a plurality of different directional characteristics, level detecting means for detecting the level of each output signal of the microphone means, and each of the level detecting means. Since it has a comparing means for comparing the levels of the output signals and a selecting means for selecting and outputting one of the output signals having the smallest output signal level according to the result of the comparison in the comparing means, It is possible to output the voice with the least noise from directions other than the desired direction for each cut-out section of the above-mentioned fixed length. Therefore, the super directivity that cannot be obtained with the conventional directional microphone is very small. Can be obtained in configurations.

The microphone device according to the present invention is
Since two unidirectional microphone units and one omnidirectional microphone unit each obtain independent directional characteristics of two channels oriented in the main axis direction,
It is possible to obtain superdirectivity of two channels with a compact structure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a microphone device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a specific example of the microphone device of the first embodiment shown in FIG.

FIG. 3 is a diagram showing polar patterns of three types of microphone devices used in the specific example shown in FIG.

FIG. 4 is a diagram for explaining the effect of the specific example shown in FIG.

FIG. 5 is a circuit diagram showing a configuration of a microphone device according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a microphone device according to a third embodiment of the present invention.

FIG. 7 is a layout diagram of three microphones used in the microphone device of the third embodiment shown in FIG.

FIG. 8 is a diagram showing three types of directional characteristics obtained by the microphone device of the third embodiment shown in FIG.

[Explanation of symbols]

M ₁ Bidirectional microphone M ₂ Sharp directional microphone M ₃ Unidirectional microphone 1 Microphone section 2 Energy calculation section 3 Comparator 4 Changeover switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ikue Akiba 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (6)

[Claims] 1. A comparison for comparing the level of each output signal detected by the level detecting means and the level detecting means for detecting the level of each output signal of the microphone means. A microphone device comprising: a means and a selection means for selecting and outputting one of the output signals having the smallest output signal level according to the result of the comparison by the comparison means. 2. The microphone device according to claim 1, wherein the microphone means has a plurality of directional characteristics with respect to a predetermined main axis. 3. The microphone device according to claim 2, wherein the microphone means comprises a plurality of microphone units having directivity characteristics different from each other with respect to a predetermined main axis. 4. The microphone device according to claim 1, wherein the microphone means obtains a plurality of directional characteristic outputs by appropriately mixing outputs of at least two microphone units having different directional characteristics. 5. The microphone means obtains directional characteristics of two channels oriented in independent main axis directions by two unidirectional microphone units and one omnidirectional microphone unit. The microphone device according to claim 1. 6. The level detecting means cuts out each output signal corresponding to each of the directional characteristics of the microphone means at any time with a window of a constant length, and calculates the total energy in the cut-out section. Item 1. A microphone device according to item 1.