JP2014033301A - Contact microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact microphone which can pick up a sound by skin conduction easily, and is difficult to pick up external noise, without causing reduction in productivity or difficulty of mass production.SOLUTION: A contact microphone collects a vibration due to a sound transmitted through the soft tissue of a human body while converting into an electric signal. The contact microphone is provided, in front of a diaphragm 13, with a multi-layer film 16 including a plurality of films arranged while spaced apart from each other and serving as a vibration transmission medium. Since silicon is not used as a vibration transmission medium, problems of reduction in productivity or difficulty of mass production can be avoided. Since a film 16-1 vibrates integrally with a skin 20, when a pick-up surface 11a is brought into contact with the skin 20, transmission loss can be neglected and a skin conduction sound is transmitted to the diaphragm 13 while transmitting through a film 16-2. When the pick-up surface 11a is not in contact with the skin 20, each film prevents intrusion of air propagation sound, and sound insulation effect works on the noise.

Description

  The present invention relates to a contact microphone that acquires sound (skin conduction sound) transmitted through a soft tissue of a human body.

  Conventionally, in a contact microphone, a structure in which the front chamber of a diaphragm is filled with silicone having an acoustic impedance substantially equal to that of a soft tissue of a human body as a vibration transmission medium and the surface of the silicone is used as a pickup surface for skin conduction sound is generally used. (For example, see Patent Document 1).

  That is, for example, as shown in FIG. 6A, the contact microphone 1 is accommodated in a case 2 made of resin, a diaphragm (diaphragm) 3 accommodated in the case 2, and the case 2. And an oscillating and electrical conversion element 4 that converts the vibration of the diaphragm 3 into an electrical signal.

  The case 2 has a cylindrical shape with a bottom, and a diaphragm front chamber 2a is formed in front of the diaphragm 3, and vibration caused by sound (skin conduction sound) transmitted through the skin 10, which is a soft tissue of the human body, is picked up from the pickup surface 1a. An opening 2b for transmitting to the diaphragm 3 is formed.

  From the pickup surface 1a to the diaphragm front chamber 2a is filled with silicone 5 having an acoustic impedance substantially equal to that of the soft tissue of the human body. The silicone 5 serves as a medium for transmitting skin conduction sound to the diaphragm 3 by bringing the pickup surface 1 a into contact with the skin 10. On the other hand, as shown in FIG. 6B, the air propagation sound is attenuated when entering the silicone 5 from the pickup surface 1a, and transmission to the diaphragm 3 is prevented or suppressed.

  In this way, by filling the diaphragm front chamber 2a with the silicone 5, the acoustic impedance matching with the soft tissue of the human body is matched to easily pick up vibration at the time of contact, and it is difficult to pick up air propagation sound at the time of non-contact. A range can be secured. The vibration due to the skin conduction sound transmitted to the diaphragm 3 through the silicone 5 is converted into an electrical signal by the oscillating electricity conversion element 4 and collected.

JP 2007-101305 A

  However, in the contact-type microphone configured as described above, when the silicone front chamber 2a is filled with the silicone 5, the silicone 5 is used as a vibration transmission medium, such as mixing of bubbles, ensuring curing time, and introducing dedicated filling equipment. There were problems such as productivity reduction and difficulty in mass production due to the above.

  On the other hand, if the silicone 5 is not used, air propagation sound is transmitted from the pickup surface 1a to the diaphragm 3 via the silicone 5 and picks up external noise when the contact microphone 1 is not in contact with the skin. Become.

  The present invention has been proposed in view of the above, and the object of the present invention is to make it easy to pick up sound due to skin conduction without causing reduction in productivity and difficulty in mass production, and to make it difficult to pick up external noise. Is to provide a microphone.

  In order to solve the above problems, the contact microphone according to the first aspect of the present invention is a contact microphone that collects sound by converting vibration due to sound transmitted through the soft tissue of a human body into an electric signal, A multilayer film 16 is provided, which functions as a vibration transmission medium and in which a plurality of films are spaced apart from each other in front of the diaphragm 13.

  The invention according to claim 2 is the contact-type microphone according to claim 1, wherein the diaphragm 12 accommodates the diaphragm 13 and the vibration-electric conversion that is accommodated in the case 12 and converts the vibration of the diaphragm 13 into an electric signal. And means (14).

  The invention according to claim 3 is the contact type microphone according to claim 1 or 2, wherein the multilayer film 16 includes first and second films 16-1 and 16-2, and first and second films. A first spacer 17-1 that is interposed in an outer peripheral portion between the first and second films 16-1 and 16-2 and separates the first and second films 16-1 and 16-2 at a predetermined interval; A second spacer 17-2 that is interposed between the outer periphery of the second film 16-2 and the case 12 and separates the second film 16-2 and the case 12 at a predetermined interval. The first film 16-1 is brought into contact with the skin 20 to collect sound.

  According to the contact-type microphone of the present invention, since silicone is not used as the vibration transmission medium, problems such as a decrease in productivity and difficulty in mass production due to the use of silicone can be avoided. Also, when the pickup surface is brought into contact with the skin, the film that adheres to the skin of the multilayer film vibrates integrally with the skin, so the transmission loss due to this film can be ignored, and the skin conduction sound adheres to the skin. The light is transmitted to the diaphragm through a film other than the film. On the other hand, when the pickup surface is not in contact with the skin, each film of the multilayer film prevents an airborne sound from entering, so that a sound insulation effect against noise works.

  Therefore, it is possible to provide a contact microphone that is difficult to pick up air-borne sound (external noise) and easily picks up skin conduction sound (sound) without lowering productivity or difficulty in mass production.

The structural example of the contact-type microphone which concerns on embodiment of this invention is shown, (a) A figure is sectional drawing in the case of collecting skin conduction sound, (b) figure is for demonstrating attenuation | damping of an air propagation sound It is sectional drawing. It is a characteristic view which shows the measurement result of the sensitivity with respect to the frequency of the skin conduction sound (voice | voice) in the case of one film and two films. It is a characteristic view which shows the measurement result of the sensitivity with respect to the frequency of the air propagation sound (external noise) in the case of one film and two films. It is a figure which compares and shows the range width, skin conduction sound, and air propagation sound in the case of one film and two films, respectively. It is a figure which compares and shows the skin conduction sound and the air propagation sound in the conventional contact microphone according to the embodiment of the present invention. The structural example of the conventional contact-type microphone is shown, (a) The figure is sectional drawing in the case of picking up skin conduction sound, (b) The figure is sectional drawing for demonstrating attenuation | damping of an air propagation sound.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  Fig.1 (a) is sectional drawing which shows the structural example of the contact-type microphone which concerns on embodiment of this invention. The contact microphone 11 collects skin conduction sound by bringing the pickup surface 11a into contact with the skin 20, which is a soft tissue of the human body, for example, the neck or the lower part of the ear.

  The contact microphone 11 includes a case 12 made of resin or the like, a diaphragm (diaphragm) 13 accommodated in the case 12, and the case 12. And an oscillating electrical conversion element (oscillating electrical conversion means) 14 for converting the electrical signal. For example, an electret or a piezoelectric element (piezo element) can be used for the oscillating electrical conversion element 14.

  The case 12 has a cylindrical shape with a bottom, and a diaphragm front chamber 12a is formed in front of the diaphragm 13, and vibration due to sound transmitted through the skin 20, which is a soft tissue of the human body, is transmitted from the pickup surface 11a to the diaphragm 13. For this purpose, an opening 12b is formed.

  A multilayer film 16 serving as a vibration transmission medium for transmitting skin conduction sound to the diaphragm 13 is provided on the pickup surface 11 a side of the case 12. In the present embodiment, the multilayer film 16 includes first and second films 16-1 and 16-2, and spacers 17-1 interposed in an outer peripheral portion between the films 16-1 and 16-2. And a second spacer 17-2 interposed in the outer peripheral portion between the second film 16-2 and the case 12.

  The first and second films 16-1 and 16-2 are made of a resin such as PET (polyethylene terephthalate) and ABS (acrylonitrile / butadiene / styrene), a metal such as SUS (stainless steel), or a combination thereof. The preferred thickness is in the range of 25 μm to 3 mm. Similarly, the spacers 17-1 and 17-2 can be made of a resin such as PET or ABS, a metal such as SUS, a double-sided tape such as a non-woven fabric with an adhesive, or a combination thereof. Is in the range of 0.1 mm to 3 mm. Here, the diameter of the opening 12b of the case 12 is 0.1 mm or more.

  Then, the pickup surface 11 a is brought into contact with the skin 20, and the vibration due to the sound (skin conduction sound) transmitted through the soft tissue of the human body is transmitted to the diaphragm 13 through the multilayer film 16, and is transmitted by the oscillating electric transducer 14. Sound is converted into an electrical signal.

  In the above configuration, when the pickup surface 11a is brought into contact with the skin 20, the film 16-1 in close contact with the skin 20 vibrates integrally with the skin 20, and the skin conduction sound is a film other than the film 16-1. The light passes through 16-2 and is transmitted to the diaphragm 13. Thus, since the skin 20 and the film 16-1 move together, the transmission loss of the film 16-1 can be ignored, so that it is easy to pick up sound due to skin conduction.

On the other hand, when the pickup surface 11a is not in contact with the skin 20, as shown in FIG. 1B, the multilayer film 16 (films 16-1 and 16-2) disposed in front of the diaphragm 13 generates external noise. Sound insulation effect works to prevent intrusion. That is, from the idea of the mass law of sound insulation, when air propagation sound passes through the medium (films 16-1 and 16-2), there is a transmission loss (effect of reducing sound pressure). It is known that the effect is proportional to mass and density from the following formula (1).
Transmission loss = 20 log (surface density × frequency) −43 [dB] (1)

  Thus, by providing the multilayer film 16 on the front surface of the diaphragm 13, air propagation sound (external noise) that enters the contact microphone 11 more than the conventional silicone-filled type is obtained while having a relatively simple structure. The skin conduction sound can be prevented and gain equivalent to that of the silicone filling type can be obtained.

  In addition, since it is not necessary to fill silicone as a vibration transmission medium, problems such as mixing of bubbles, securing curing time, introducing dedicated filling equipment, and other problems such as reduced productivity and difficulty in mass production due to the use of silicone Can be avoided.

  As a result, it is possible to produce a contact-type microphone in which air propagation sound (external noise) is difficult to pick up and skin conduction sound (sound) is easy to pick up without causing a decrease in productivity and difficulty in mass production.

  The present inventors conducted a demonstration experiment of skin conduction sound (sound) and air-borne sound (external noise) using the contact microphone. In this experiment, a PET material having a diameter of about 6 mm and a thickness of 50 μm was used for each of the films 16-1 and 16-2, and the thickness of the spacers 17-1 and 17-2 was about 0.5 mm.

  FIG. 2 is a characteristic diagram showing measurement results of sensitivity to the frequency of skin conduction sound (sound) in the case of one film and two films, and FIG. 3 is also a measurement of sensitivity to frequency of air propagation sound (external noise). It is a characteristic view which shows a result. As shown by the alternate long and short dash line (single layer) 30 and the solid line (multiple layer) 40 in FIG.

  On the other hand, as indicated by the alternate long and short dash line 30 and the solid line 40 in FIG. 3, in the frequency band of 3.4 KHz or less, the airborne sound is less sensitive in the multilayer than in the single layer. Since the actual use band has a frequency of about 300 Hz to about 3.4 KHz, it can be seen that it is difficult to pick up noise by using multiple layers.

  FIG. 4 is a diagram comparing the range width, skin conduction sound, and air propagation sound when the number of films is one and two. In FIG. 4, shaded bar-like areas 51 and 52 represent range widths, 61 and 62 represent skin conduction sound gain [dBV], and 71 and 72 represent air propagation sound gain [dBV], respectively. As can be seen from FIG. 4, the external noise value (air propagation sound) is reduced by 13 [dBV] by using a multilayer (here, two layers) film, but the sound sensitivity (skin conduction sound) is only 3 [dBV]. It has not declined. In other words, it was confirmed that the sound conduction microphone was easy to pick up voice and hard to pick up external noise.

  FIG. 5 shows comparison between skin conduction sound and air propagation sound in a conventional microphone filled with silicone and a contact microphone according to an embodiment of the present invention. FIG. 5 shows average values of the range width, skin conduction sound, and air propagation sound at a frequency of about 300 Hz to 3.4 KHz. In FIG. 5, shaded bar-like areas 51 and 52 represent range widths, 61 and 62 represent skin conduction sound gain [dBV], and 71 and 72 represent air propagation sound gain [dBV], respectively. .

  As is clear from FIG. 5, the sensitivity performance of the skin conduction sound is almost the same, and the sensitivity of the air-borne sound is lower in the contact microphone of the present invention than in the conventional product.

  Therefore, according to the present invention, it is possible to provide a contact microphone that easily picks up sound due to skin conduction and hardly picks up external noise without causing a decrease in productivity and difficulty in mass production.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, although the example which comprises the multilayer film 16 by a two-layer film was shown, of course, three or more layers may be sufficient. Further, not only the number of layers of the film but also the thickness of the spacer may be set according to the required acoustic characteristics.

DESCRIPTION OF SYMBOLS 1, 11 Contact-type microphone 1a, 11a Pickup surface 2, 12 Case 2a, 12a Diaphragm front chamber 2b, 12b Opening part 3, 13 Diaphragm 4, 14 Vibratory electrical conversion element (vibration electrical conversion means)
5 Silicone 16 Multi-layer film 16-1, 16-2 First and second films 17-1, 17-2 Spacer 10, 20 Skin 30 Dotted line 40 Solid line 51, 52 Bar-shaped region (range width)
61, 62 Skin conduction sound gain 71, 72 Air propagation sound gain

  The present invention relates to a contact microphone that acquires sound (skin conduction sound) transmitted through a soft tissue of a human body.

  Conventionally, in a contact microphone, a structure in which the front chamber of a diaphragm is filled with silicone having an acoustic impedance substantially equal to that of a soft tissue of a human body as a vibration transmission medium and the surface of the silicone is used as a pickup surface for skin conduction sound is generally used. (For example, see Patent Document 1).

  That is, for example, as shown in FIG. 6A, the contact microphone 1 is accommodated in a case 2 made of resin, a diaphragm (diaphragm) 3 accommodated in the case 2, and the case 2. And an oscillating and electrical conversion element 4 that converts the vibration of the diaphragm 3 into an electrical signal.

  The case 2 has a cylindrical shape with a bottom, and a diaphragm front chamber 2a is formed in front of the diaphragm 3, and vibration caused by sound (skin conduction sound) transmitted through the skin 10, which is a soft tissue of the human body, is picked up from the pickup surface 1a. An opening 2b for transmitting to the diaphragm 3 is formed.

  From the pickup surface 1a to the diaphragm front chamber 2a is filled with silicone 5 having an acoustic impedance substantially equal to that of the soft tissue of the human body. The silicone 5 serves as a medium for transmitting skin conduction sound to the diaphragm 3 by bringing the pickup surface 1 a into contact with the skin 10. On the other hand, as shown in FIG. 6B, the air propagation sound is attenuated when entering the silicone 5 from the pickup surface 1a, and transmission to the diaphragm 3 is prevented or suppressed.

  In this way, by filling the diaphragm front chamber 2a with the silicone 5, the acoustic impedance matching with the soft tissue of the human body is matched to easily pick up vibration at the time of contact, and it is difficult to pick up air propagation sound at the time of non-contact. A range can be secured. The vibration due to the skin conduction sound transmitted to the diaphragm 3 through the silicone 5 is converted into an electrical signal by the oscillating electricity conversion element 4 and collected.

JP 2007-101305 A

  However, in the contact-type microphone configured as described above, when the silicone front chamber 2a is filled with the silicone 5, the silicone 5 is used as a vibration transmission medium, such as mixing of bubbles, ensuring curing time, and introducing dedicated filling equipment. There were problems such as productivity reduction and difficulty in mass production due to the above.

  On the other hand, if the silicone 5 is not used, air propagation sound is transmitted from the pickup surface 1a to the diaphragm 3 via the silicone 5 and picks up external noise when the contact microphone 1 is not in contact with the skin. Become.

  The present invention has been proposed in view of the above, and the object of the present invention is to make it easy to pick up sound due to skin conduction without causing reduction in productivity and difficulty in mass production, and to make it difficult to pick up external noise. Is to provide a microphone.

In order to solve the above problems, the contact microphone according to the first aspect of the present invention is a contact microphone that collects sound by converting vibration due to sound transmitted through the soft tissue of a human body into an electric signal, A multilayer film 16 that functions as a vibration transmission medium and in which a plurality of films are spaced apart from each other is provided in front of the diaphragm 13, the diaphragm 13 is accommodated in the case 12, and the diaphragm 12 includes the diaphragm 13. The vibration-electric conversion means 14 for converting vibration into an electric signal is provided, and the multilayer film 16 includes first and second films 16-1 and 16-2, and these first and second films 16-. 1st spacer 17-1 which is interposed in the perimeter part between 1 and 16-2, and separates the 1st and 2nd films 16-1 and 16-2 at predetermined intervals, and the 2nd film 6-2, and a second spacer 17-2 interposed between the outer periphery of 6-2 and the case 12 and separating the second film 16-2 and the case 12 at a predetermined interval, The first film 16-1 is brought into contact with the skin 20 and vibrated, and the skin conduction sound is transmitted through the second film 16-2 and collected .

  According to the contact-type microphone of the present invention, since silicone is not used as the vibration transmission medium, problems such as a decrease in productivity and difficulty in mass production due to the use of silicone can be avoided. Also, when the pickup surface is brought into contact with the skin, the film that adheres to the skin of the multilayer film vibrates integrally with the skin, so the transmission loss due to this film can be ignored, and the skin conduction sound adheres to the skin. The light is transmitted to the diaphragm through a film other than the film. On the other hand, when the pickup surface is not in contact with the skin, each film of the multilayer film prevents an airborne sound from entering, so that a sound insulation effect against noise works.

  Therefore, it is possible to provide a contact microphone that is difficult to pick up air-borne sound (external noise) and easily picks up skin conduction sound (sound) without lowering productivity or difficulty in mass production.

The structural example of the contact-type microphone which concerns on embodiment of this invention is shown, (a) A figure is sectional drawing in the case of collecting skin conduction sound, (b) figure is for demonstrating attenuation | damping of an air propagation sound It is sectional drawing. It is a characteristic view which shows the measurement result of the sensitivity with respect to the frequency of the skin conduction sound (voice | voice) in the case of one film and two films. It is a characteristic view which shows the measurement result of the sensitivity with respect to the frequency of the air propagation sound (external noise) in the case of one film and two films. It is a figure which compares and shows the range width, skin conduction sound, and air propagation sound in the case of one film and two films, respectively. It is a figure which compares and shows the skin conduction sound and the air propagation sound in the conventional contact microphone according to the embodiment of the present invention. The structural example of the conventional contact-type microphone is shown, (a) The figure is sectional drawing in the case of picking up skin conduction sound, (b) The figure is sectional drawing for demonstrating attenuation | damping of an air propagation sound.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  Fig.1 (a) is sectional drawing which shows the structural example of the contact-type microphone which concerns on embodiment of this invention. The contact microphone 11 collects skin conduction sound by bringing the pickup surface 11a into contact with the skin 20, which is a soft tissue of the human body, for example, the neck or the lower part of the ear.

  The contact microphone 11 includes a case 12 made of resin or the like, a diaphragm (diaphragm) 13 accommodated in the case 12, and the case 12. And an oscillating electrical conversion element (oscillating electrical conversion means) 14 for converting the electrical signal. For example, an electret or a piezoelectric element (piezo element) can be used for the oscillating electrical conversion element 14.

  The case 12 has a cylindrical shape with a bottom, and a diaphragm front chamber 12a is formed in front of the diaphragm 13, and vibration due to sound transmitted through the skin 20, which is a soft tissue of the human body, is transmitted from the pickup surface 11a to the diaphragm 13. For this purpose, an opening 12b is formed.

  A multilayer film 16 serving as a vibration transmission medium for transmitting skin conduction sound to the diaphragm 13 is provided on the pickup surface 11 a side of the case 12. In the present embodiment, the multilayer film 16 includes first and second films 16-1 and 16-2, and spacers 17-1 interposed in an outer peripheral portion between the films 16-1 and 16-2. And a second spacer 17-2 interposed in the outer peripheral portion between the second film 16-2 and the case 12.

  The first and second films 16-1 and 16-2 are made of a resin such as PET (polyethylene terephthalate) and ABS (acrylonitrile / butadiene / styrene), a metal such as SUS (stainless steel), or a combination thereof. The preferred thickness is in the range of 25 μm to 3 mm. Similarly, the spacers 17-1 and 17-2 can be made of a resin such as PET or ABS, a metal such as SUS, a double-sided tape such as a non-woven fabric with an adhesive, or a combination thereof. Is in the range of 0.1 mm to 3 mm. Here, the diameter of the opening 12b of the case 12 is 0.1 mm or more.

  Then, the pickup surface 11 a is brought into contact with the skin 20, and the vibration due to the sound (skin conduction sound) transmitted through the soft tissue of the human body is transmitted to the diaphragm 13 through the multilayer film 16, and is transmitted by the oscillating electric transducer 14. Sound is converted into an electrical signal.

  In the above configuration, when the pickup surface 11a is brought into contact with the skin 20, the film 16-1 in close contact with the skin 20 vibrates integrally with the skin 20, and the skin conduction sound is a film other than the film 16-1. The light passes through 16-2 and is transmitted to the diaphragm 13. Thus, since the skin 20 and the film 16-1 move together, the transmission loss of the film 16-1 can be ignored, so that it is easy to pick up sound due to skin conduction.

On the other hand, when the pickup surface 11a is not in contact with the skin 20, as shown in FIG. 1B, the multilayer film 16 (films 16-1 and 16-2) disposed in front of the diaphragm 13 generates external noise. Sound insulation effect works to prevent intrusion. That is, from the idea of the mass law of sound insulation, when air propagation sound passes through the medium (films 16-1 and 16-2), there is a transmission loss (effect of reducing sound pressure). It is known that the effect is proportional to mass and density from the following formula (1).
Transmission loss = 20
log (surface density × frequency) −43 [dB] (1)

  Thus, by providing the multilayer film 16 on the front surface of the diaphragm 13, air propagation sound (external noise) that enters the contact microphone 11 more than the conventional silicone-filled type is obtained while having a relatively simple structure. The skin conduction sound can be prevented and gain equivalent to that of the silicone filling type can be obtained.

  In addition, since it is not necessary to fill silicone as a vibration transmission medium, problems such as mixing of bubbles, securing curing time, introducing dedicated filling equipment, and other problems such as reduced productivity and difficulty in mass production due to the use of silicone Can be avoided.

  As a result, it is possible to produce a contact-type microphone in which air propagation sound (external noise) is difficult to pick up and skin conduction sound (sound) is easy to pick up without causing a decrease in productivity and difficulty in mass production.

  The present inventors conducted a demonstration experiment of skin conduction sound (sound) and air-borne sound (external noise) using the contact microphone. In this experiment, a PET material having a diameter of about 6 mm and a thickness of 50 μm was used for each of the films 16-1 and 16-2, and the thickness of the spacers 17-1 and 17-2 was about 0.5 mm.

  FIG. 2 is a characteristic diagram showing measurement results of sensitivity to the frequency of skin conduction sound (sound) in the case of one film and two films, and FIG. 3 is also a measurement of sensitivity to frequency of air propagation sound (external noise). It is a characteristic view which shows a result. As shown by the alternate long and short dash line (single layer) 30 and the solid line (multiple layer) 40 in FIG.

  On the other hand, as indicated by the alternate long and short dash line 30 and the solid line 40 in FIG. 3, in the frequency band of 3.4 KHz or less, the airborne sound is less sensitive in the multilayer than in the single layer. Since the actual use band has a frequency of about 300 Hz to about 3.4 KHz, it can be seen that it is difficult to pick up noise by using multiple layers.

  FIG. 4 is a diagram comparing the range width, skin conduction sound, and air propagation sound when the number of films is one and two. In FIG. 4, shaded bar-like areas 51 and 52 represent range widths, 61 and 62 represent skin conduction sound gain [dBV], and 71 and 72 represent air propagation sound gain [dBV], respectively. As can be seen from FIG. 4, the external noise value (air propagation sound) is reduced by 13 [dBV] by using a multilayer (here, two layers) film, but the sound sensitivity (skin conduction sound) is only 3 [dBV]. It has not declined. In other words, it was confirmed that the sound conduction microphone was easy to pick up voice and hard to pick up external noise.

  FIG. 5 shows comparison between skin conduction sound and air propagation sound in a conventional microphone filled with silicone and a contact microphone according to an embodiment of the present invention. FIG. 5 shows average values of the range width, skin conduction sound, and air propagation sound at a frequency of about 300 Hz to 3.4 KHz. In FIG. 5, shaded bar-like areas 51 and 52 represent range widths, 61 and 62 represent skin conduction sound gain [dBV], and 71 and 72 represent air propagation sound gain [dBV], respectively. .

  As is clear from FIG. 5, the sensitivity performance of the skin conduction sound is almost the same, and the sensitivity of the air-borne sound is lower in the contact microphone of the present invention than in the conventional product.

  Therefore, according to the present invention, it is possible to provide a contact microphone that easily picks up sound due to skin conduction and hardly picks up external noise without causing a decrease in productivity and difficulty in mass production.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, although the example which comprises the multilayer film 16 by a two-layer film was shown, of course, three or more layers may be sufficient. Further, not only the number of layers of the film but also the thickness of the spacer may be set according to the required acoustic characteristics.

DESCRIPTION OF SYMBOLS 1, 11 Contact-type microphone 1a, 11a Pickup surface 2, 12 Case 2a, 12a Diaphragm front chamber 2b, 12b Opening part 3, 13 Diaphragm 4, 14 Vibratory electrical conversion element (vibration electrical conversion means)
5 Silicone 16 Multi-layer film 16-1, 16-2 First and second films 17-1, 17-2 Spacer 10, 20 Skin 30 Dotted line 40 Solid line 51, 52 Bar-shaped region (range width)
61, 62 Skin conduction sound gain 71, 72 Air propagation sound gain

Claims (3)

A contact microphone that picks up sound by converting vibration caused by sound transmitted through the soft tissue of the human body into an electrical signal,
A contact-type microphone comprising a multilayer film (16) that functions as a vibration transmission medium and in which a plurality of films are spaced apart from each other in front of a diaphragm (13).   A case (12) for housing the diaphragm (13); and a vibroelectric conversion means (14) for accommodating the diaphragm (13) and converting the vibration of the diaphragm (13) into an electric signal. The contact microphone according to claim 1, wherein: The multilayer film (16) is interposed between the first and second films (16-1, 16-2) and the outer peripheral portion between the first and second films (16-1, 16-2). A first spacer (17-1) for separating the first and second films (16-1, 16-2) at a predetermined interval, and an outer peripheral portion of the second film (16-2). And a second spacer (17-2) which is interposed between the second film (16-2) and the case (12) at a predetermined interval, and is interposed between the case (12) and the case (12). The contact-type microphone according to claim 1 or 2, wherein the first film (16-1) is brought into contact with the skin (20) to collect sound.

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