JP2007043516A - Microphone for picking up body propagation of articulatory expiration sounds - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microphone which has performance improved furthermore and picks up body propagation of articulatory expiration sounds. <P>SOLUTION: A microphone 10 includes a bottomed cylindrical case 12 made of, for example, a polymer resin, and an outer peripheral edge of a metallic plate 14 having a parabolic inside surface 16 is fixed to an opening edge of the case 12, and a condenser microphone 22 is disposed in a position corresponding to a focus of the parabola in a space defined by the inside surface 16, and a urethane elastomer is filled so as to wrap the condenser microphone 22 therein to form a contact part 26. A contact face 20 of the contact part 26 is stuck to a skin of a human body, and a sound signal waveform of NAM from the condenser microphone 22 is taken out as an electric signal. Since the contact part is made of the urethane elastomer, a band of a sound signal to be taken out can be widened, and the inclusion of friction noise is reduced. Furthermore, since the urethane elastomer itself used in the contact part has adhesion, the contact part can be easily and surely brought into close contact with the skin, and the adhesion is kept for a long period of time to be able to extend the estimated usable period. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microphone that collects in-vivo conduction of articulatory exhalation sounds, and more particularly to a microphone that is used for an audio input interface using non-audible murmur (NAM), for example.

  In Non-Patent Document 1, Patent Document 1, and Non-Patent Document 2, the inventors proposed a voice input interface using NAM.

  However, the term “non-audible tweet” (NAM) is a coined word proposed by the inventors, etc., that refers to speech behavior that is self-processing in the mouth and is difficult for the surrounding people to hear the content. . Speaking acoustically, it can be defined that a silent exhalation sound not accompanied by vocal cord vibration is tuned by a change in acoustic filter characteristics due to the movement of the speech organ, and is conducted mainly through the soft tissue of the human head. Therefore, in general terms, the present invention can be said to be a microphone for collecting in-vivo conduction of articulatory exhalation sounds that are not accompanied by vocal cord vibrations. Such a microphone is sometimes referred to as a NAM microphone.

  Non-Patent Document 1 and Patent Document 1 propose a stethoscope-type microphone, that is, a microphone in which a suction cup made of synthetic resin is mounted on the surface of a diaphragm. Such a stethoscope-type NAM microphone has a problem that it is difficult to clearly collect NAM because the band is narrow.

  Non-Patent Document 2 proposes a soft silicone type NAM microphone.

This soft silicone type NAM microphone is a microphone in which OECM (Open Electric Condenser Microphone) is embedded in soft silicone. Since the condenser microphone (ECM) is originally designed to collect airway sounds, it has a structure that transmits late vibrations to the vibrating electrode plate through a small hole in the ECM surface. However, the surface metal with a small hole is scraped off to create an ECM in a form in which the vibrating electrode is completely exposed, which is named OECM, and this OECM is soft silicone (for example, for dental technicians. For example, It was made to completely embed it with a silicone impression agent “DUPLICONE: vinyl polysiloxane” manufactured by Matsukaze Co., Ltd.
Yuki Nakajima, Hideki Sasaoka, Campbell Nick, Kiyohiro Shikano "Non-audible tweet recognition" IEICE Transactions D-II Vol. J87-D-II No. 9 pp. 1757-1764 (September 2004) WO2004 / 021738A1 Nakajima Yuki, Takefue Koji, Kashioka Hideki, Shikano Kiyohiro, Campbell Nick, “NAM Interface Communication” Information Processing Society of Japan 2004-H1-109 (6) 2004-SLP-52 (6) 2004/7/16 pp. 33-40

  Compared with the stethoscope-type microphones of Non-Patent Document 1 and Patent Document 1, the conventional technology of Non-Patent Document 2 can efficiently collect NAM.

  However, in order to make the use of the NAM voice input interface more active, further improvement of the performance of such a NAM microphone is required.

  Therefore, the main object of the present invention is to provide a microphone that collects the body conduction of articulatory exhaled sounds with further improved performance.

  The invention of claim 1 is a microphone for collecting in-vivo conduction of articulatory exhalation sound that is attached to a human body so as to be in contact with the skin and is not accompanied by vibration of the vocal cords. It is a microphone provided with the contact part which wraps around the mechanical-electrical conversion microphone, and the surface of a contact part becomes a contact surface to skin.

  In the invention of claim 1, for example, a mechanical-electrical conversion microphone such as a condenser microphone (22: reference numeral indicating a corresponding part in the embodiment; the same applies hereinafter) is provided, and the mechanical-electrical conversion microphone is wrapped ( Urethane elastomer is molded to embed. The surface (20) of the contact portion (26) made of this urethane elastomer is a contact surface with the human skin. Then, the body conduction (NAM) of the articulation exhalation sound without the vocal cord vibration input from the contact surface propagates through the contact portion and is taken out as an electrical signal from the mechanical-electrical conversion microphone.

  In the invention of claim 1, since urethane elastomer is used for the contact portion with the human skin, the acoustic impedance of the contact portion can be very close to the acoustic impedance of the human skin. Compared with what was used for the part, the broadband becomes possible. In addition, since the contact portion of the urethane elastomer has a much better adhesion performance with human skin than that of conventional soft silicone, there is little mixing of frictional noise generated between the contact portion and the skin in the necessary band. Therefore, the overall acoustic performance is improved compared to the conventional one.

  The invention of claim 2 further includes a metal plate having a curved inner surface serving as a reflecting surface, the mechanical-electrical conversion microphone is disposed in a space defined by the inner surface of the metal plate, and the inner surface is filled with a urethane elastomer. The microphone according to claim 1.

  In the invention of claim 2, the metal plate (14) is provided, and the inner surface (16) of the metal plate is formed into an inverted conical shape that becomes larger upward or outward. The mechanical-electrical conversion microphone (20) is then placed in such a curved inner surface (14). Therefore, the NAM that has propagated through the contact portion (24) reaches the mechanical-electrical conversion microphone directly or reflected by the metal plate inner surface (16). Therefore, the mechanical-electrical conversion microphone can receive NAM efficiently.

  The invention according to claim 3 is the microphone according to claim 2, further comprising a vibration suppressing member attached to the outer surface of the metal plate.

  In the invention of claim 3, since a vibration suppressing member (vibration damper) such as hard silicone is provided on the outer surface of the metal plate (14), unnecessary vibration components other than NAM are input to the mechanical-electrical conversion microphone. Can be prevented. If the above-mentioned hard silicone is put in the case (12), this case also functions as a vibration suppressing member.

  According to a fourth aspect of the present invention, the inner surface of the metal plate is curved in a parabolic shape, and the mechanical-electrical conversion microphone is disposed at a position corresponding to the focal point of the parabolic shape. It is a microphone.

  According to the fourth aspect of the present invention, since the mechanical-electrical conversion microphone is disposed at the focal point corresponding position of the parabolic inner surface, the NAM reflected by the inner surface (16) of the metal plate efficiently reaches the mechanical-electrical conversion microphone.

  The invention of claim 5 comprises a mechanical-electrical conversion microphone and a urethane elastomer, and includes a contact part that covers the mechanical-electrical conversion microphone. The surface of the contact part becomes a contact surface, and acoustic vibration is input from the contact surface. It is a microphone.

  The microphone of the invention of claim 5 can be used not only for human NAM but also for other acoustic detection applications.

  According to this invention, since the contact portion is made of urethane elastomer, the acoustic impedance of the contact portion can be approximated very well with the acoustic impedance of human skin, so conventional soft silicone is used for the contact portion. Compared to those, it is possible to widen the audio signal taken out from the microphone. In addition, since the contact portion made of urethane elastomer has very good adhesion performance with human skin, there is little mixing of frictional noise. Therefore, the overall acoustic performance is improved compared to the conventional one.

  Furthermore, since the urethane elastomer used for the contact portion itself has adhesiveness, it adheres to any of human skin, metal, and plastic, and the microphone of the present invention is not limited to the so-called NAM microphone, but has other uses, For example, it can also be used as a microphone for taking out micro-acoustics. Furthermore, since such an adhesive force does not disappear even if it is once removed, it can be directly adhered to the object or the object part. Moreover, even if the adhesive strength is reduced, the adhesive strength can be recovered by taking a measure such as washing with water. Therefore, the usable period of the microphone can be extended.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  A NAM microphone 10 according to an embodiment of the present invention shown in FIG. 1 includes a case 12 having a top opening and a bottomed cylindrical shape made of, for example, an acrylic resin (dental polymerization resin). A bowl-shaped or dish (dish) -shaped metal plate 14 is bonded so that the periphery of the case 12 is positioned at the upper edge. The metal plate 14 has an inner surface 16 that curves in a parabolic shape. The material of the metal plate 14 is tin in the embodiment, but other metal materials may be used. A very small through hole 18 is formed at the bottom of the metal plate 14.

  In the space formed by the parabola-shaped inner surface 16 of the metal plate 14, there is a case where the body conduction (hereinafter referred to as “NAM”) of the articulation exhalation sound input from the contact surface 20 with the human skin (not shown). .)) Is disposed as a mechanical-electrical conversion microphone for converting an electrical signal into an electrical signal. Capacitor microphone 22 includes two electrodes 22a and 22b, and generates a change in capacitance in response to mechanical vibration caused by the propagated NAM. The change in capacitance is connected to electrodes 22a and 22b, that is, the electrodes 22a and 22b. The lead wires 24a and 24b are taken out.

  The lead wires 24 a and 24 b are drawn out from the bottom through hole 18 of the metal plate 14. The lead wires 24a and 24b are connected to an amplifier (not shown) for amplifying the electric signal, for example.

  For example, the capacitor microphone 22 is held by the lead wires 24 a and 24 b at a distance from the inner surface or the bottom surface 18 of the metal plate 14. However, considering that the shape of the inner surface 16 of the metal plate 14 is parabolic as described above, and the inner surface 16 of the metal plate 14 functions as a NAM reflector, the condenser microphone 22 has a parabolic reflection. It is arranged or held at a position corresponding to the focus position of the mirror. Thereby, the NAM reflected by the inner surface 16 of the metal plate 14 is efficiently input to the capacitor microphone 22.

  In the space defined by the parabolic inner surface 16 of the metal plate 14, the condenser microphone 22 is held at the focal point as described above. This space is filled with urethane elastomer, and the urethane elastomer is sounded. It becomes a medium or contact portion 26. The sound medium is a medium for propagating sound wave vibration to the condenser microphone 22. Since the condenser microphone 22 is held at a distance from the inner surface 16 as described above, the urethane elastomer goes around the entire circumference of the condenser microphone 22. That is, the capacitor microphone 22 is wrapped (embedded) in the urethane elastomer within the inner surface 16 of the metal plate 14.

  Note that urethane is a polyurethane that is a synthetic polymer having a urethane bond —NHCOO— in the main chain, and exhibits rubber-like elasticity when subjected to a cross-linking structure treatment with an aromatic or polyhydric alcohol. become. This is a urethane elastomer. Elastomer is a high-molecular substance with remarkable elasticity.

  In the experiment, it was necessary to obtain a stock solution to test various shapes and hardnesses. Therefore, the inventors obtained a stock solution as a urethane gel (main agent and curing agent) as an example from the website of Exeal Corporation, Inc. (URL: http://www.exeal.co.jp). In the experiment, a product called “Human Skin Gel Hardness 15” was used.

  As described above, since the inner surface 16 of the metal plate 14 has a parabolic shape, the contact portion 26 made of urethane elastomer filled therein gradually increases in diameter from the position of the condenser microphone 22 toward the upper side. 1 shows an inverted conical shape, and the uppermost outermost surface is the contact surface 20 described above. A rubber ring 28 made of, for example, tolyl rubber is attached to the outer periphery of the contact surface 20. The rubber ring 28 is bonded to the upper edge of the case 12 by an adhesive 30 such as epoxy. This rubber ring 28 is necessary when the contact portion 26 made of urethane elastomer is molded, and may be removed after molding or may not be used depending on the case.

  Further, a vibration suppressing member 34 made of a synthetic resin material such as hard silicone (relative to soft silicone) is attached to the outer surface (surface opposite to the inner surface 16) 32 of the case 12 and the metal plate 14. The vibration suppressing member 34 functions as a vibration damper for preventing noise components such as unnecessary sound wave vibration from entering the condenser microphone 22 from the outer surface side of the metal plate 14. Since the case 12 is also effective in preventing such vibration wraparound, it similarly functions as a vibration suppressing member.

  In the case of the conventional soft silicone type NAM microphone disclosed in the previous Non-Patent Document 2, a portion corresponding to the contact portion 26 of the example was formed of soft silicone. In the case of a soft silicone type microphone, the soft silicone itself has no adhesive force, and therefore there is a large wall in the method of attaching the contact surface (corresponding to the contact surface 20 in the embodiment) to the human skin, for example. It was. The reason is that the silicone oil that can be used as a release agent always oozes out from the contact area of the soft silicone, so that it cannot be adhered to the skin with a double-sided tape or general adhesive, This is also due to the fact that a light pressure is required to bring the smooth silicone contact surface into close contact with fine uneven skin without air. Therefore, in the experiments by the inventors, conventionally, for example, a headband-like thing (a headband is a plastic molded into a C shape as a whole, which a girl wears on the head and suppresses or decorates the hair. In such a method, the contact surface is displaced just by moving the neck, and frictional noise between the skin and the skin is mixed as noise. Daily wearing was difficult.

  I thought about fixing the parts other than the sound sensitive part of the contact surface with double-sided tape, but again the friction between the contact surface and the skin will not disappear, so noise will not disappear, and you will have to craft with new double-sided tape each time you wear it. It must be very cumbersome. Therefore, daily wear is difficult even with this method.

  On the other hand, in the microphone 10 of the embodiment, since the urethane elastomer itself used for the contact portion 26 is adhesive, the human body can be used even if the contact surface 20 of the contact portion 26 does not use any auxiliary means. Close contact with the skin. Therefore, in the case of the microphone 10, daily wear on the subject is possible. Moreover, since the adhesive strength of such urethane elastomer does not disappear even if it is once removed, it can be reattached to the skin as it is. Even if the adhesive strength falls, the adhesive strength can be recovered by taking a measure such as washing with water. Therefore, the microphone 10 in which the contact portion 26 is made of urethane elastomer can be attached to the skin stably and easily for a very long time. That is, the usable period of the microphone 10 can be extended.

  Then, a part of the electrode of the capacitor microphone 22 is applied to a specific part of the human body, for example, a bone protrusion called a mastoid immediately behind the ear hole of the skull base, and the contact surface 20 is applied to the skin (not shown) of such part. Is adhered, NAM is transmitted from the soft tissue under the skin and propagated from the contact surface 20 into the contact portion 26. The NAM that has entered from the contact surface 20 travels straight through the contact portion 26 and directly reaches the condenser microphone 22, and further, is reflected by the inner surface 16 of the metal plate 14 and reaches the condenser microphone 22. Therefore, disposing the condenser microphone 22 at the position of the parabolic focus on the inner surface 16 of the metal plate 14 is advantageous in that the reflection component of the NAM can be used efficiently.

  In the experiments conducted by the inventors, the acoustic performance of the microphone 10 of the example in which the contact portion 26 is formed of urethane elastomer and the conventional soft silicone type microphone as a comparative example were actually measured. However, in the comparative example, it was set as the same shape structure as the microphone 10 of an Example except that the contact part was formed with soft silicone.

  Specifically, a soft silicone microphone was mounted on the right side and the microphone 10 of the example was mounted on the left side, and the NAM uttered sound was simultaneously recorded in stereo with the same amplifier. Of course, the left and right amplification factors are the same.

  Moreover, the condenser microphone of the same model of the same company was used whether it was a soft silicone type microphone or the microphone 10 of the example. That is, the example and the comparative example differ in the sound structure (contact portion 26) with the same structure, the former being urethane elastomer and the latter being soft silicone. However, the soft silicone of the soft silicone microphone was fixed to the skin with a double-sided tape (strong) using rubber glue. At this time, the surrounding rubber ring 28 was mainly adhered. In the microphone 10 of the example using a urethane elastomer as a sound medium, it was adhered to the skin with the adhesive strength of the urethane elastomer itself.

  The contents of the test utterances were read in the NAM utterance that “every reality was twisted towards me”.

  FIG. 2 shows the measurement result of the comparative example, and FIG. 3 shows the measurement result of the microphone 10 of the example. In both cases, the top shows the NAM audio signal waveform, and the bottom shows the spectrum.

  2 and 3 are compared with each other. In the case of FIG. 2, the maximum value of the amplitude is “14684” and the minimum value is “−29201”, whereas in the case of FIG. The maximum value was “32767” and the minimum value was “−32768”. From the comparison of the amplitudes of the signal waveforms, it can be seen that the sensitivity in the case of FIG. 3, that is, the microphone 10 of the embodiment is better than that in the case of FIG. 2, that is, the conventional soft silicone type microphone. Similarly, comparing the lower spectrum of FIG. 2 with the lower spectrum of FIG. 3, it can be seen that the case of FIG. 3 has a wider bandwidth. In other words, in the microphone 10 of this embodiment, the sensitivity and the band can be improved by forming the contact portion 26 with urethane elastomer as compared with the conventional soft silicone type microphone. The reason is that the acoustic impedance of the urethane elastomer used in the example can be more closely approximated to the acoustic impedance of the human body (skin) than the acoustic impedance of soft silicone, so on the propagation path from the human body to the condenser microphone 22 This is because the loss of is minimized.

  4 and 5 show the results of measuring the degree of mixing of frictional noise between the comparative example (soft silicone type microphone) and the microphone 10 of the example. However, in the same manner as in the comparative example and the example, measurement was performed using the same amplifier with the neck mounted in the optimum position and the neck moved back and forth and left and right.

  As shown in FIG. 4, in the case of the comparative example, frictional noise was mixed in a wide band due to friction caused by neck motion. On the other hand, in the case of the example, although there was a coarse baseline fluctuation, no frictional noise was found in the required frequency band (1 kHz-4 kHz). This is because, as described above, the adhesive strength of the urethane elastomer is good, and the microphone 10 of the example can stably adhere to the skin as compared with the soft silicone type microphone.

  As described above, in the example, by forming the contact portion 26 with urethane elastomer, it was possible to simultaneously improve the acoustic performance and the adhesion performance as compared with the soft silicone type microphone.

  Note that, as described above, the urethane elastomer used for the contact portion 26 has adhesiveness to itself, and thus adheres to any of human skin, metal, and plastic. Therefore, the microphone 10 according to the embodiment can be used not only as a so-called NAM microphone, but also as a microphone for another use, for example, a microphone for extracting minute sound or minute vibration.

  Various methods are conceivable for manufacturing the microphone 10 of the embodiment, but in the experiment conducted by the inventors, the following procedure was used.

  As a first stage, as shown in FIG. 6, a capacitor microphone 22 is floated on the metal plate 14 by lead wires 24a and 24b from the inner surface 16 (at a distance), and preferably in a space in the inner surface 16, preferably an inner surface parabola. Hold at the focal position of the shape. Hard silicone was applied to the outer surface 32 of the metal plate 14 to form a vibration suppressing member 34. At this time, the lead wires 24a and 24b of the capacitor microphone 22 are fixed by the vibration suppressing member 34 and pulled out therefrom.

  On the other hand, an outer mold 36 having an inner surface shape and dimensions corresponding to the outer shape and dimensions of the case 12 is prepared, and a softened polymerization resin 12a and a curing agent (not shown) are placed in the outer mold 36. Then, as described above, the metal plate 14 holding the condenser microphone 22 in the space of the inner surface 16 and having the vibration suppressing member 34 attached to the outer surface 32 is placed in the center of the outer mold 36 as shown by an arrow in FIG. Push in. Then, the polymerization resin 12 a is eliminated by the vibration suppressing member 34, and the polymerization resin 12 a adheres to the periphery of the vibration suppressing member 34 and becomes the shape of the case 12. FIG. 7 shows a state in which the outer mold 36 is removed after curing in this state.

  Next, as shown in FIG. 8, an adhesive 30 is applied to the upper edge of the case 12 to bond the rubber ring 28.

  Thereafter, urethane gel (main agent and curing agent) is potted in a space defined by the inner surface 16 of the metal plate 14. Eventually, the urethane gel hardens, and this becomes the contact portion 26 of the urethane elastomer.

  However, such a manufacturing method can be changed as appropriate.

FIG. 1 is an illustrative sectional view showing an embodiment of the present invention. FIG. 2 is a graph showing the measurement results of the NAM audio signal waveform and spectrum of the comparative example. FIG. 3 is a graph showing the measurement results of the NAM audio signal waveform and spectrum of the FIG. 1 embodiment. FIG. 4 is a graph showing the measurement result of the frictional noise of the comparative example. FIG. 5 is a graph showing the measurement results of the frictional noise in the embodiment of FIG. FIG. 6 is an illustrative sectional view showing a first stage in the process of manufacturing the microphone of the embodiment of FIG. FIG. 7 is an illustrative sectional view showing a second stage of the manufacturing process of the microphone of the embodiment of FIG. FIG. 8 is an illustrative sectional view showing a third stage of the manufacturing process of the microphone of the embodiment of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Microphone 12 ... Case 14 ... Metal plate 16 ... Inner surface 20 ... Contact surface 22 ... Condenser microphone 26 ... Contact part 34 ... Vibration suppression member

Claims (5)

A microphone that is attached to a human body so as to come into contact with the skin and collects the body conduction of articulatory exhalation sounds without vibration of the vocal cords,
A mechanical-electrical conversion microphone and a urethane elastomer, comprising a contact portion for enclosing the mechanical-electrical conversion microphone;
A microphone in which a surface of the contact portion is a contact surface to the skin. A metal plate having a curved inner surface that serves as a reflective surface;
The mechanical-electrical conversion microphone is disposed in a space defined by the inner surface of the metal plate,
The microphone according to claim 1, wherein the urethane elastomer is filled in the inner surface.   The microphone according to claim 2, further comprising a vibration suppressing member attached to an outer surface of the metal plate.   The microphone according to any one of claims 1 to 3, wherein the inner surface of the metal plate is curved in a parabolic shape, and the mechanical-electrical conversion microphone is disposed at a position corresponding to a focal point of the parabolic shape. A mechanical-electrical conversion microphone, and a urethane elastomer, comprising a contact portion that covers the mechanical-electrical conversion microphone,
The microphone in which the surface of the contact portion becomes a contact surface, and acoustic vibration is input from the contact surface.