JPH026479B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an airflow microphone suitable for close speech that is resistant to external sounds and howling.

FIG. 1 shows an example of a conventional close-talk microphone. Figure a is an external perspective view, and figure b is a sectional view thereof. In the figure, 1 is a case, 2 is a mesh, and 3 is a power generation mechanism. This microphone is a sound pressure gradient type microphone with bidirectionality, and rejects sounds from both the front and back directions, that is, the directions of arrows A and B.

Close-talk microphones having such a structure have the disadvantage that they cannot be used in high-noise environments such as construction sites, airports, and quarry sites because they discard external noise propagating through the air. Another drawback was that howling was likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional close-talk microphones described above, and to provide an airflow microphone that is resistant to external sounds and howling and is moisture resistant.

The present invention is characterized by a supporting base material, an electroacoustic transducing element whose one end is supported by the supporting base material, and a volume flow molded to cover at least the electroacoustic transducing element support portion of the supporting base material and the electroacoustic transducing element. a damper member having a large hysteresis and having a shape that causes a pressure difference between the side to which the electroacoustic transducer is attached and a vibration absorbing member provided on the opposite side of the support base material to the side on which the electroacoustic transducer is attached. , is resistant to noise, less prone to howling, and has good moisture resistance.

First, the principle of the present invention will be explained. When vocalizing, the vocal cords vibrate due to exhalation. The glottis opens and closes in accordance with its cycle, allowing continued exhaled airflow through the glottis. That is, the continuous flow of exhaled air becomes the source of the voice.

This expiratory volume flow waveform is closely related to the temporal change in glottis area (area waveform). Since this glottis area waveform changes depending on the position and shape of the vocal cords during vocalization, the mode of vocal fold vibration, etc., the volume flow waveform of the sound source in the glottis includes a voice signal component.

The volume flow with such audio signal components passes through the vocal tract, which is a resonant cavity and controls the airflow velocity, and is radiated from the open end, ie, the lips.
At this time, the volume flow at the open end changes under the influence of the vocal tract. That is, the spectrum of the volume flow at the open end is the product of the spectrum of the sound source and the transfer characteristics of the vocal tract.

From the above, it is clear that the volume flow output from the open end, that is, the lips, has an audio signal component. Incidentally, these matters are known in the medical field.

The present invention is based on a completely new idea of the inventor,
This device picks up sound from the volume flow radiated from the lips to the outside world.

The present invention will be explained below with reference to Examples. FIG. 2a is a perspective view of the first embodiment of the present invention, and FIG. 2b is a sectional view taken along the line A--A in FIG. 2a. In the figure 11
12 is an electroacoustic transducer whose one end is supported by the core support base 11. Reference numeral 12 denotes a support base made of a heavy metal material that is difficult to transmit vibrations, such as brass, iron, or lead. As the electroacoustic transducer 12, for example, a bimorph or single-layer piezoelectric member made of a piezoelectric member such as barium titanate porcelain made into a rectangular shape is used. Reference numeral 13 denotes an electroacoustic transducer support portion of the support base 11, which is filled with an insulating material to prevent electrical signals from leaking into the support base 11. Reference numeral 14 denotes a damper member that molds the entire electroacoustic transducer support 13 and electroacoustic transducer 12. Hydrodynamically, the damper member 14 molds the entire electroacoustic transducer support 13 and the electroacoustic transducer 12. It is formed from a material with so-called large hysteresis that has a shape that receives displacement and that reduces the Q of the resonant frequency of the electroacoustic transducer 12 that converts the displacement into an electrical quantity by nonlinear vibration. As this damper member 14,
For example, it can be made of cylindrical or prismatic silicone rubber with a polygonal cross section close to circular.

Further, 15 is a damper member 14 of the support base material 11.
This is a vibration absorbing member made of silicone resin, polyurethane, etc. attached to the opposite side. Reference numeral 16 denotes a cord for extracting the electrical signal of the audio picked up by the electroacoustic transducer 12, which connects one end of the electroacoustic transducer 12 to the support base 1.
1. It is taken out to the outside through the vibration absorbing member 15.

In manufacturing an airflow microphone having such a structure, first, the electroacoustic transducer element 12 is installed in the support base material 11, and then the damper member 14 is installed.
If the vibration absorbing member 15 is made by molding, it is easy to manufacture and can be made at low cost.

The airflow microphone of this embodiment is attached to a headset by fitting its vibration absorbing member 15 into an annular portion (not shown) provided at one end of the headset. When the headset is worn by a speaker, the airflow microphone is placed near the speaker's mouth. When a speaker speaks, a volume stream containing an audio signal component is radiated from the speaker's mouth toward the microphone. When this volume flow hits the cylindrical damper member 14, the damper member 1
The side facing the speaker's mouth in No. 4 receives a pressing force in a direction away from the mouth due to the volume flow. On the other hand, on the rear side of the damper member 14, the volume flow
4, a turbulent volumetric flow occurs. This causes the damper member 14 to receive a force in a direction toward the mouth. However, since the fluid pushed apart by the damper member 14 is a viscous fluid, the pressing force in the direction away from the mouth is greater than the force in the direction towards the mouth caused by the turbulent flow. This pressure difference causes the damper member 14 to flex. On the other hand, this pressure difference depends on the volume flow waveform. Therefore, the damper member 14 produces a deflection of a magnitude corresponding to the volume flow waveform. In this way, the speaker's speech is converted into an electrical signal and sent through the cord 16 to the subsequent electrical circuit.

As mentioned above, the damper member 14 is made of silicone rubber or the like. This damper member 14 has a large hysteresis in the amount of displacement with respect to processing pressure.
It is flexible and its acoustic impedance is much larger than that of air.

Therefore, a portion of air vibration sounds such as external sounds and noises transmitted from the outside world are reflected by the surface of the damper member 14. Note that since the airflow microphone of this embodiment is molded with a damper member, its mass and resistance are large, and it does not vibrate due to reflection of this external sound. On the other hand, the other part absorbed by the damper member 14 is dumped because the hysteresis of the damper member 14 is large. Therefore, the electroacoustic transducer 12 is not subjected to vibrations due to external sounds, noise, etc. Furthermore, since distant sounds enter the microphone from all sides in the same phase, they cancel each other out, and this also prevents the electroacoustic transducer 12 from vibrating. Therefore, it can be said that the microphone of this embodiment is resistant to external sounds or noise.

In addition, since the diameter member 14 is made of a material with large hysteresis as described above, the Q of the natural resonance of the vibration system of the electroacoustic transducer 12 is
is reduced by the damper member 14, and the free vibration of the vibration system becomes nonlinear. Therefore, the electroacoustic exchange element 12 no longer has a specific resonance point, making it difficult for howling to occur.

Furthermore, in this embodiment, a vibration absorbing member 15 of the direct airflow microphone is attached to an annular portion provided at one end of the headset. Therefore, air vibration sounds such as external sounds and noises thrown away by the headset are absorbed by the vibration absorbing member 15 and are not transmitted to the support base 11 made of a heavy metal material. Even if the sound is transmitted, the supporting base material 11 made of a heavy metal material reduces the transmitted vibration due to its weight, so the electroacoustic transducer element 12 is affected by the sound thrown away by the headset. It does not vibrate and there is no risk of discarding noise through the headset or causing howling.

In the first embodiment of the present invention described above, the electroacoustic transducer element 12 is provided approximately on the central axis of the cylindrical damper member, and therefore does not have directivity.

Next, an embodiment in which the airflow microphone of the present invention is provided with directivity will be described. Figure 3 shows the second embodiment of the present invention.
A perspective view of an example is shown.

The reference numerals in the figure indicate the same ones as in FIG. 2a. The structural difference between this embodiment and the first embodiment is that the electroacoustic transducer 12 is connected to a cylindrical damper member 14.
This is a point located eccentrically from the central axis of the In the microphone of this embodiment, when a volume flow is input from the direction of arrow A, that is, when the volume flow is applied to the electroacoustic transducer element 12 through the thin damper member, the intensity is lower than when the volume flow is applied from other directions. You can pick up louder sounds.

FIGS. 4a and 4b show a third embodiment of the present invention having the same meaning as the second embodiment. FIG. 4a is a perspective view, and FIG. 4b is a sectional view taken along line A--A in FIG. 4a. Note that the reference numerals in the figure indicate the same ones as in FIG. 2a.

This embodiment differs from the first embodiment in that the electroacoustic transducer 12 is supported on the support base 11 at a predetermined angle with respect to the central axis of the cylindrical damper member 14, The free end of the electroacoustic transducer 12 is located close to the surface of the damper member 14, the supporting base material 11 is made of a hard material such as epoxy resin, polycarbonate, or baked material, and the vibration absorbing member 15 is This is the point where the microphone support 17 is inserted.

With this configuration, when a volume flow is applied from the direction of arrow B, as in the second embodiment, a greater intensity can be obtained compared to when the volume flow is applied from other directions. In addition, the airflow microphone of this embodiment has the following features via the microphone support 17:
Although it is supported by a headset or the like, air vibration sounds such as external sounds and noises thrown away by the headset, microphone support 17, etc. are absorbed by the vibration absorbing member 15 and hardly transmitted to the support base 11. Furthermore, in this embodiment, when epoxy resin or polycarbonate is used as the support base material 11, the support base material 1
1 and the electroacoustic transducer element 12 can be integrally molded, so the manufacturing process is simpler than that of the first and second embodiments.

This third embodiment differs from the first embodiment in that it has directivity and is easy to manufacture, but it goes without saying that it has the same effects as the first embodiment in other respects.

FIG. 5 shows a fourth embodiment of the invention. This embodiment differs from the second embodiment shown in FIG. 3 in that a silicone oil 19 placed in a cylindrical container 18 made of metal or resin such as silicone rubber is used instead of the damper member 14. At the point. In this embodiment, since the silicone oil 19 functions as a damper, it is possible to obtain the same effect as in the second embodiment of the present invention described above.

Note that a damper member such as rubber may be further provided outside the cylindrical container 18 of this embodiment.

FIG. 6a is a perspective view of a fifth embodiment of the present invention, and FIG. 6b is a sectional view taken along line A--A. This embodiment differs from the third embodiment in that protrusions 11a and 11b are provided on the adhesion surface of the damper member 14 and the vibration absorption member 15 of the support base material 11,
and the shape of the microphone support 17 is modified. Note that the symbols other than 11a and 11b indicate the same or equivalent components as in FIG. 4a.

In this embodiment, the supporting base material 11 has protrusions 11a,
11b, the contact area between the supporting base material 11 and the damper member 14, or the supporting base material 11 and the vibration absorbing member 15 increases, and there is an effect that the adhesion strength between the two is strong.

FIG. 7 shows a sixth embodiment of the invention. The reference numerals in the figure indicate the same or equivalent parts as in FIG. 4a. This embodiment differs from the third embodiment described above in that the supporting base material 11 is embedded in the damper member 14, and the entire microphone is molded with the damper member 14.
In this way, the sound transmitted through the headset or microphone support 17 is reflected or absorbed by the damper member 14, so that the same effect as in the third embodiment can be obtained.

FIG. 8 shows a seventh embodiment of the invention. In the figure, 20 is a container made of a material that does not transmit vibrations, such as silicone rubber, and 21 is a liquid such as silicone oil placed in the container 20. Other numerals indicate the same or equivalent items as in FIG. 4a.

This embodiment differs from the third embodiment shown in FIG. 4a in that a liquid such as silicone oil is used in place of the vibration absorbing member 15.

In this embodiment as well, the sound transmitted through the headset or microphone support 17 is blocked by the container 20 and the liquid 21, so that the same effects as in the third and sixth embodiments are achieved.

FIG. 9 shows a perspective view of an eighth embodiment of the invention.
This embodiment differs from the previous embodiments in that the damper member 14 is spherical. Note that the reference numerals in the figure indicate the same or equivalent components as in FIG. 4a.

When the microphone of this embodiment is attached near the mouth and the speaker speaks, a volume flow hits the spherical damper member 14. Then, the side of the damper member 14 facing the mouth receives a pressing force, and the rear side generates a turbulent volumetric flow and is sucked. Therefore, the spherical damper member 14 vibrates in accordance with the volume flow waveform that changes depending on the audio signal, thereby causing the electroacoustic transducer element 12 to deflect. In this way, the speaker's speaking voice is converted into an electrical signal.

Although various embodiments of the present invention have been described above, the illustrated and described embodiments are only a part of the present invention, and other modifications as described below are possible.

(1) In each of the above embodiments, the electroacoustic transducer 1
2 is parallel to the axis of the damper member 14 and those not parallel to the axis of the damper member 14, those using heavy metal and hard resin as the support base material 11, and those where no microphone support is provided on the vibration absorbing member 15. Although representative examples of the above-mentioned types have been described, in each of the above-described embodiments, any one of the above two types may be arbitrarily selected. for example,
The electroacoustic transducer 12 in the first embodiment may be tilted with respect to the axis of the damper member 14 as in the third embodiment, or the first embodiment may be modified by attaching a microphone support 17, etc. It's okay.

(2) In each of the above embodiments, the damper member 14 has a cylindrical shape and a spherical shape, but the present invention is not limited thereto. The point is that when a volume flow hits a damper member, a pressing force acts on the side of the damper member that the volume flow hits, and on the back side, a turbulent flow is formed by the flow of the volume flow. Any shape is sufficient as long as it cancels out external sounds coming from the outside. Therefore, it may be columnar with an elliptical cross section, an elliptical sphere, or even a prism with a polygon close to a circle in cross section.

(3) A rod-shaped enclosure may be provided that surrounds the entire damper member 14 using the microphone support 17 as a support part. This prevents fingers, foreign objects, etc. from directly hitting the damper member 14, thereby preventing damage to the electroacoustic transducer element 12.

(4) A weight may be provided at the free end of the electroacoustic transducer 12. In this way, the pickup efficiency is further improved.

(5) In each of the above embodiments, the supporting base material 11
In addition, a protrusion as shown in the fourth embodiment may be provided. Alternatively, the contact surface of the support base material 11 with the damper member 14 and the vibration absorbing member 15 may be made rough.

FIG. 10 shows how to use the conventional close-talk microphone shown in FIG. 1 and the microphone of this embodiment shown in FIG. A waveform diagram is shown when the voice "o" is picked up.

As can be seen by comparing the waveforms of the two, the waveforms of the voices picked up by the conventional close-talking microphone and the close-talking microphone of this embodiment are almost the same.

FIG. 11 is a waveform diagram when audio is picked up in an environment with white noise. Figure a
shows the waveform produced by the conventional microphone shown in FIG. 1, and FIG. 4b shows the waveform produced by the microphone of the present embodiment shown in FIG. 4a.

When I input a continuous "A" sound at 30dB to 40dB, both were able to pick up a clear sound. However, when the noise is greater than 40 dB, as is clear from Figure 1A, conventional close-talk microphones are unable to discard noise and pick up the input "u" sound. In contrast, the microphone of this example was able to clearly pick up the "u" sound, as is clear from FIG. Therefore, it was demonstrated that the microphone of this example is resistant to external sounds and noise.

FIGS. 12 and 13 show waveform diagrams of the howling test, respectively, showing the waveform diagram of the conventional close-talking microphone shown in FIG. 1 and the waveform diagram of the airflow microphone of the present embodiment shown in FIG. 4a. This waveform measurement was performed by placing the speaker and microphone approximately 1 meter apart, changing the volume continuously, and inputting an "o" sound.

When I input the "o" sound shown in Figure 12a into a conventional microphone and gradually increased the volume from the -40 dB volume position, howling occurred around the -3 dB volume position. In contrast, an "o" sound as shown in Figure 13a, which is similar to Figure 12a, was input to the microphone of this example, and the volume was gradually increased from the -40dB volume position. However,
Howling did not occur even when the volume was at 0dB. Therefore, it was demonstrated that the airflow microphone of this example is resistant to howling.

As described above, the airflow microphone of the present invention has great effects in that it is resistant to noise and hardly causes howling. Therefore, it can be used in high noise environments such as construction sites, airports, and quarry sites. Additionally, it is resistant to feedback, so it can be used near speakers.

Furthermore, since the electroacoustic transducer element is molded with a damper member, it is resistant to moisture and is robust.
Therefore, it has the effect of having a long life.

Furthermore, a supporting base material for an airflow microphone according to the present invention,
Since the damper member and the vibration absorbing member can also be made by molding, there is an effect that the manufacturing cost is simple and the cost is low.

[Brief explanation of drawings]

Fig. 1 is an external perspective view and a sectional view of a conventional close-talk microphone, Fig. 2a, Fig. 3, Fig. 4a, Fig. 5.
6a, 7, 8 and 9 are the first, second, third, fourth, fifth, and third embodiments of the present invention, respectively.
2b, 4b and 6b are respectively sectional views of the first, third and fifth embodiments, and FIG. 10 is a conventional Figure 11 is a waveform diagram when audio is picked up with the close-talking microphone of this embodiment and the close-talking microphone of this embodiment, Figure 11 is a waveform diagram of both microphones when audio is picked up under white noise generation, and Figure 12 is the waveform diagram of the conventional microphone. FIG. 13 shows a waveform diagram when a howling test was performed using the close-talking microphone of the present invention. FIG. DESCRIPTION OF SYMBOLS 11...Supporting base material, 12...Electroacoustic conversion element, 13...Electroacoustic conversion element support part, 14...
Damper member, 15... Vibration absorbing member, 16...
Cord, 17...Microphone support, 18...
Container, 19...Oil, 20...Container, 21...
liquid.

Claims (1)

[Scope of Claims] 1. A supporting base material, an electroacoustic transducing element whose one end is supported by the supporting base material, and a volume molded to cover at least the electroacoustic transducing element support portion of the supporting base material and the electroacoustic transducing element. A damper member having a large hysteresis and having a shape that causes a pressure difference between the side to which the flow hits and the opposite side thereof, and a vibration absorbing member provided on the side of the support base opposite to the side to which the electroacoustic transducer is attached. An airflow microphone characterized by: 2. The airflow microphone according to claim 1, wherein the damper member has a cylindrical shape, an elliptical cylinder shape, a spherical shape, or an ellipsoidal shape. 3. Claims 1 or 2, characterized in that the electroacoustic conversion element extends substantially on the central axis or diameter of the damper member, so that the microphone has omnidirectionality. Airflow microphone as described. 4. The airflow microphone according to claim 1 or 2, wherein at least a free end of the electroacoustic transducer is located near the surface of the damper member, giving the microphone directivity. 5. Any one of claims 1 to 4, wherein the vibration absorbing member is integrally formed of the same material as the damper member, and the supporting base material is embedded in the damper member. Airflow microphone described in .