JP2013074915A - Microphone for collecting biological sounds and electronic stethoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microphone for collecting biological sounds wherein the mixing of external environment noise or slide noise hardly occurs and which can sensitively collect biological sounds and allows the broadening of a sound collection band.SOLUTION: The microphone 1 for collecting biological sounds includes: a plate-like first biological sound propagation part 20 functioning as a biological sound propagation part to a microphone unit 10, having the front surface stuck to the body surface of a subject, and having the rear surface abutted on or brought close to the microphone unit 10; and a second biological sound propagation part 30 made of a material having a Shore A hardness lower than the first biological sound propagation part 20, filled in a space sectionalized by a casing 40 and the first biological sound propagation part 20, and embedded with the microphone unit 10.

Description

  The present invention relates to an electronic auscultation apparatus and a living body sound collecting microphone incorporated in the electronic auscultation apparatus.

  Stethoscopes have been widely used as devices for diagnosing body sounds in the medical field. A stethoscope usually has a chest piece part that collects a body sound, a tube that is connected to the chest piece part and transmits the body sound as a sound wave, and an ear part that is disposed at the tip of the tube. In the chest piece portion, a metal portion having a cone shape inside is used as a bell mode, and a diaphragm made of a resin film is used as a diaphragm mode. These modes are properly used depending on the symptoms of the patient's disease and the examination site.

  The shape of the stethoscope chestpiece has been optimized over a long history. In recent years, electronic stethoscopes have been developed that convert biological sounds into electrical signals, perform signal processing, and then convert them back into sound waves for diagnosis using electronic technology for stethoscopes. Stethoscope digitization technology has made it possible to store sound data and share information, and to transfer auscultation techniques. Furthermore, it is expected that the signs of hidden diseases will be revealed by analysis of auditory data.

  Some electronic stethoscope chestpieces are equipped with a microphone. Patent Documents 1 and 2 disclose microphones that collect non-audible muttering sounds from the vicinity of the head or neck. Non-audible murmur sound is sound that does not accompany regular vibration of the vocal cords, and is vibration sound that propagates from the outside to a non-audible soft tissue part in the body. Such an audio signal is collected not by a normal microphone that detects vibration in an acoustic space but by a meat conduction microphone that collects a body sound in the body.

  FIG. 7 is a schematic cross-sectional view showing the configuration of the meat conduction microphone 100 disclosed in Patent Document 1. As shown in FIG. The meat conduction microphone 100 includes a condenser microphone 110 and a hardened soft silicone rubber 120 that has an acoustic impedance close to that of the soft tissue part of the body and functions as a contact part that conducts input sound from the skin surface to the capacitor microphone 110. The meat conduction microphone 100 also includes a hard frame 130, a lead wire 140 for deriving the received vibration sound as an electrical signal, an external noise soundproof space 150, and the like.

  The meat conduction microphone 100 collects sound by bringing the surface of the hardened soft silicone rubber 120 into contact with the skin. An external noise soundproof space 150 is provided between the hard frame 130 and the cured soft silicone rubber 120. Thereby, mixing of external noise is prevented. The condenser microphone 110 is embedded in the hardened soft silicone rubber 120. A signal obtained from the condenser microphone 110 is transmitted to the outside via the signal line 140. It is described that the hardness of the cured soft silicone rubber 120 is desirably 30 (Shore A) or less.

  FIG. 8 shows a schematic cross-sectional view of the meat conduction microphone 200 disclosed in Patent Document 2. As shown in FIG. The meat conduction microphone 200 includes a microphone unit 210, a meat conduction sound propagation part 220, an inner cover member 230, an adhesive sound insulation part 240, an outer cover member 250, a signal line 260, and the like.

  The meat conduction sound propagation part 220 is made of a soft member that closely adheres one surface to the skin surface and propagates the meat conduction sound that propagates through the human body. The meat conduction propagation part 220 is made of a material whose acoustic impedance characteristic is close to the acoustic impedance characteristic of the body part of the human body, such as urethane elastomer or silicon. Thereby, the meat conduction sound can be efficiently propagated from the human body (skin) to the meat conduction sound propagation unit 220. The inner cover member 230 covers the entire portion of the meat conduction sound propagation unit 220 other than the contact surface with the skin surface, and the microphone unit 210 is accommodated. The adhesive sound insulation unit 240 is made of a urethane elastomer that is a soft member having adhesiveness to human skin, and is formed so as to cover the entire outside of the inner cover member 230. The outer cover member 250 covers the entire outside of the adhesive sound-insulating part 240 other than the skin adhesion part, and forms an exterior.

WO2005 / 067340 Publication FIG. 8 JP 2008-027441 A

  Conventional auscultation targets were heart sounds, lung sounds, or breathing sounds (sound collection band is about 20 Hz to 500 Hz), but a technology for collecting minute living body sounds that were not previously sound collection targets, With the wideband technology that expands the band that can collect sound, there is a great expectation to make a new association with the disease to discover the disease at an early stage or contribute to preventive medicine. In order to realize these, there is a strong demand for a technology that eliminates noise while collecting biological sound with high sensitivity and realizes a wider sound collection range.

  The present invention has been made in view of the above background, and the object of the present invention is to prevent external environmental noise and sliding noise from being mixed, to collect biological sounds with high sensitivity, and to collect a sound collection band. It is an object to provide a living body sound collecting microphone capable of broadening the band and an electronic auscultation device incorporating the microphone.

The biological sound collecting microphone according to the present invention is a biological sound collecting microphone that collects a biological sound, a microphone unit that converts the biological sound into an electric signal, a housing that houses the microphone unit, and the microphone unit. A plate-like first living body sound propagation portion that functions as a living body sound conducting portion for the body, has a surface closely attached to the body surface of the subject, and a back surface that is in contact with or close to the microphone unit; A second living body sound propagation portion made of a material having a Shore A hardness lower than that of the living body sound propagation portion, filled in a space defined by the casing and the first living body sound propagation portion, and embedded in the microphone unit With.
The first body sound propagation part preferably has a Shore A hardness of 40 or more.
The second living body sound propagation part preferably has a Shore A hardness of less than 40.
Preferable examples of the first biological sound propagation unit include a viscoelastic body or a rubber elastic body.
Preferable examples of the second biological sound propagation unit include a viscoelastic body or a rubber elastic body.
Particularly preferable examples of the first biological sound propagation part include silicone rubber or urethane elastomer.
Particularly preferable examples of the second biological sound propagation part include silicone rubber or urethane elastomer.
An electronic auscultation apparatus according to the present invention incorporates the biological sound collecting microphone.
Note that the acoustic impedance characteristic of the region where the body sound is collected can be calculated from a value estimated from the density, the elastic modulus (Young's modulus), the speed of sound propagating through the tissue, and the like.

  According to the biological sound collecting microphone according to the present invention, (1) the acoustic impedance characteristic is close to the acoustic impedance characteristic of the biological sound collection region as the first biological sound propagation unit, and (2) the shape is a plate. (3) Since the surface thereof is in close contact with the body surface of the subject and (4) it is in contact with or close to the microphone unit, it is possible to efficiently conduct the biological sound to the microphone unit. Furthermore, the second body sound propagation part is filled in the space defined by the first body sound propagation part and the housing, a material having a Shore A hardness lower than that of the first body sound propagation part is used as a material, and Since the microphone unit is embedded, noise and environmental noise due to sliding with the subject during auscultation are unlikely to occur, and external noise can be suppressed by increasing attenuation of external noise. As a result, it is possible to efficiently conduct the body sound to the microphone unit.

  According to the present invention, a living-body sound collecting microphone capable of collecting biological sound with high sensitivity and widening the sound collecting band, and a built-in microphone that are unlikely to be mixed with external environmental noise and sliding noise. There is an excellent effect that an electronic auscultation apparatus can be provided.

(A) is a schematic sectional drawing of the microphone for biological sound collection which concerns on 1st Embodiment, (b) is a schematic plan view of the microphone for biological sound collection which concerns on 1st Embodiment. The schematic sectional drawing of the microphone for biological sound collection which concerns on a modification. The schematic sectional drawing of the microphone for biological sound collection which concerns on 2nd Embodiment. The spectrum of the heart sound in the biological sound collection microphone according to the second embodiment. (A) is the figure which plotted the frequency with respect to the Shore A hardness of the 1st biological sound propagation part which concerns on 2nd Embodiment, (b) is a figure which shows the relationship between a frequency and sound pressure. The schematic sectional drawing of the microphone for biological sound collection which concerns on 3rd Embodiment. 1 is a schematic cross-sectional view of a meat conducting microphone according to Patent Document 1. FIG. FIG. 6 is a schematic cross-sectional view of a meat conducting microphone according to Patent Document 2. The spectrum of the heart sound in the biological sound collection microphone according to the comparative example.

  Hereinafter, an example of an embodiment to which the present invention is applied will be described. It goes without saying that other embodiments may also belong to the category of the present invention as long as they match the gist of the present invention. In addition, the sizes and ratios of the members in the following drawings are for convenience of explanation, and the actual ones may not necessarily be those sizes and ratios. Further, in the following embodiments and modifications, the same type members are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

[First Embodiment]
FIG. 1A is a schematic cross-sectional view of a biological sound collecting microphone 1 incorporated in the electronic auscultation apparatus according to the first embodiment, and FIG. 1B is a first biological body of the biological sound collecting microphone 1. The schematic plan view from the sound propagation part side is shown. The biological sound collecting microphone 1 includes a microphone unit 10, a first biological sound propagation unit 20, a second biological sound propagation unit 30, a housing 40, a signal line 50, and the like.

  The electronic auscultation apparatus according to the first embodiment is a so-called electronic stethoscope, and includes a living body sound collecting microphone 1, a tube (not shown), a sound wave conversion unit (not shown), an ear part (not shown), and the like. The data converted into the electrical signal by the living body sound collecting microphone 1 is transmitted to the tube via the signal line 50, and then converted into the sound wave again by the sound wave converting unit to diagnose the body sound from the ear part. . The electronic auscultation apparatus may be a device further including a storage unit that stores body sounds, an analysis unit that analyzes the obtained body sounds, a data transfer unit, a data display unit, and the like. Moreover, the electronic auscultation apparatus which does not have the structure of a general stethoscope and has a memory | storage part, an analysis part, the display part of an analysis result, etc. may be sufficient.

  In the first embodiment, an example of auscultating a body sound of a human body chest 60 as a subject will be described. However, the living body sound collecting microphone and the electronic auscultation apparatus incorporating the same according to the present invention are not limited to the living body chest, and can be widely applied to living body auscultation of the soft tissue portion of the living body. The body sound includes all body sounds such as heart sounds, lung sounds, breathing sounds, blood flow sounds, peristaltic sounds, swallowing sounds, fetal sounds such as fetal heart sounds. The target of listening is not limited to a person, and may be various animals including dogs, cats, livestock, and the like.

  The microphone unit 10 converts the biological sound conducted through the first biological sound propagation unit 20 and the second biological sound propagation unit 30 into an electrical signal. In the microphone unit 10, the entire sensing unit that senses the vibration of the biological sound is embedded in the second biological sound propagation unit 30. The body sound is conducted to the microphone unit 10 via the first body sound propagation unit 20 and the second body sound propagation unit 30.

  The microphone unit 10 can employ, for example, an electric condenser microphone. Moreover, you may employ | adopt the silicon microphone by another small dynamic microphone, a piezoelectric element, and MEMS (micro electro mechanical system).

  The surface 21 of the first biological sound propagation unit 20 is a part to be brought into close contact with the body surface of the subject, and the close contact target may be the body surface in the body during surgery in addition to the skin surface. In the first embodiment, an example in which the surface 21 of the first biological sound propagation unit 20 is brought into close contact with the skin surface 61 of the biological breast 60 will be described. The shape of the first biological sound propagation unit 20 is a disk shape as shown in FIG. The body sound collecting microphone 1 collects body sound by bringing the surface 21 of the first body sound propagation unit 20 into contact with the skin surface 61 of the body chest 60. A side surface of the first biological sound propagation unit 20 is fixed by a housing 40. In 1st Embodiment, although the surface of the housing | casing 40 and the surface 21 of the 1st biological sound propagation part 20 have shown the same surface, the surface 21 of the 1st biological sound propagation part 20 is a housing | casing. You may protrude from the surface of 40.

  The first body sound propagation unit 20 plays a role of conducting body sound conducted in the living body to the microphone unit 10. The material of the first biological sound propagation unit 20 is such that the acoustic impedance characteristic is close to the acoustic impedance characteristic of the region where the biological sound is collected. Here, the acoustic impedance in the subject refers to an acoustic impedance obtained by synthesizing a conduction sound of a soft tissue portion such as skin, subcutaneous tissue, organ, muscle, and hard tissue composed of a skeleton. The acoustic impedance characteristic of the region where the body sound is collected can be calculated from a value estimated from the density of the region (for example, tissue), the elastic modulus (Young's modulus), the speed of sound propagating through the tissue, and the like. The inherent acoustic impedance can be estimated by the product of density and sound speed.

  When the acoustic impedance difference between the biological tissue and the first biological sound propagation unit 20 is large, it is difficult for the biological sound to propagate to the first biological sound propagation unit 20. Since the first living body sound propagation unit 20 and the living body cannot be directly compared by acoustic impedance or Shore A hardness, the speed of sound is used as a common parameter. That is, a living body is a mixture of parts (cortical bone, cancellous bone, internal organs, muscle fibers, fat, tendons, blood vessels, blood, water, etc.) having various acoustic characteristics from water to bone. The composition ratio is different, and the sound speed of the part is also a composition of each eigenvalue. The sound speed of a living body generally shows some value in the range of about 1400 m / s to 4000 m / s. Therefore, the first living body sound propagation unit 20 can be adapted with a certain range accordingly. That is, the first biological sound propagation unit 20 is set so that the sound velocity of the biological tissue can be propagated in the range of 1400 m / s to 4000 m / s. For example, an elastomer having a Shore A hardness of 40 exhibits a speed of sound of 1000 m / s to 2000 m / s.

  The living body chest 60 is characterized in that a skeleton is formed at a high density near the surface of the living body together with soft tissues such as skin, organs, muscles, fats, and blood vessels. The body sound to be heard is a conduction sound that has been conducted through all the tissues. The sound velocity (sound propagation velocity) of the soft tissue part is usually about 1400 m / s to 1600 m / s, although there are some differences depending on the organ and tissue. On the other hand, the sound speed of the bone is approximately 3000 m / s to 4000 m / s, which is faster than the soft tissue part. Therefore, when the conduction sound is not only the conduction sound of the soft tissue but also the conduction sound of the skeleton part having a high Young's modulus, the apparent sound speed is higher than the sound speed of the soft tissue part. Therefore, it is preferable that the first living body sound propagation unit 20 has viscoelastic characteristics that are excellent in adhesion and shape followability and can maintain the required Young's modulus to some extent.

  The first biological sound propagation unit 20 has high hardness, Young's modulus, high anti-sliding noise characteristics, small acoustic impedance difference with the biological chest, and the sound speed in the first biological sound propagation unit 20 is What has a characteristic substantially equivalent to the sound speed in a biological body is preferable. By setting the Shore A hardness to 40 or more, it is possible to shift the band on the low frequency side in a lower direction, shift the band on the high frequency side in a higher direction, and achieve a wider band. As a result, it is possible to improve the frequency characteristics and take out the body sound with high efficiency. Since the upper limit value of the Shore A hardness of the first living body sound propagation part 20 can be suitably applied even in the recommended measurement range 90 for a member having rubber elasticity, the preferable upper limit value of the Shore A hardness is defined by the measurement limit. Can not. In addition, Shore A hardness is performed by the method as described in ASTM standard (ASTM D2240) or JIS standard (JIS K6523).

  The thickness of the first biological sound propagation unit 20 is preferably 2 mm or less because attenuation occurs when the propagation distance of the biological sound is increased. From the viewpoint of avoiding an increase in the acoustic characteristics of the lower layer member. , 0.1 mm or more is preferable.

  The material of the first living body sound propagation unit 20 can be used without particular limitation as long as it satisfies the above characteristics, but preferred examples include viscoelastic bodies and rubber elastic bodies. Here, the viscoelastic body refers to an object having the property of having both viscosity and elasticity, and examples thereof include a polymer substance such as a resin. The rubber elastic body refers to an object having a Young's modulus in a range of about 1 to 10 MPa at room temperature, extending with a slight stress, and returning to the original state when an external force is removed. Examples of the synthetic rubber include polyether rubber, polysulfide rubber, and silicone rubber. Particularly preferable examples of the first biological sound propagation unit 20 include silicone rubber and urethane elastomer.

  When urethane elastomer, silicone rubber, or the like is used as the first living body sound propagation unit 20, the adhesion to the skin surface is improved. That is, the first living body sound propagation unit 20 can be in close contact with the skin surface and can be more firmly held on the human body. However, among urethane elastomers, when a urethane elastomer with particularly high adhesion is used as the first biological sound propagation unit 20, the difference between the acoustic impedance and the acoustic impedance of the soft composition of the human body increases, and the propagation efficiency of biological sounds is increased. May worsen (attenuation will increase). Therefore, it is preferable to use a urethane elastomer with low adhesion when using a urethane elastomer.

  By separating the first biological sound propagation unit 20 and the microphone unit 10 from each other, it is possible to attenuate the high frequency range of the biological sound more effectively, and it is possible to obtain characteristics with better noise resistance characteristics. However, if the distance between the first living body sound propagation unit 20 and the microphone unit 10 becomes too large, the sound pressure itself to be detected is lowered. Therefore, it is important to appropriately adjust the separation distance between the first biological sound propagation unit 20 and the microphone unit 10 according to the types of the first biological sound propagation unit 20 and the second biological sound propagation unit 30. . From the viewpoint of performing biological sound conduction with high sensitivity, the distance between the first biological sound propagation unit 20 and the microphone unit 10 is preferably 1 mm or less. The first biological sound propagation unit 20 and the microphone unit 10 are brought into contact with each other without being separated like the biological sound collecting microphone 1A shown in FIG. Also good.

  The second biological sound propagation unit 30 includes a back surface 22 which is a surface opposite to the surface 21 which is a surface to be brought into close contact with the skin surface 61 in the first biological sound propagation unit 20, the microphone unit 10, and an internal side surface 41 of the housing 40. It is filled in the space divided into two. The second biological sound propagation unit 30 plays a role of holding the microphone unit 10. The second biological sound propagation unit 30 also serves as a filter that increases the acoustic impedance difference between the biological chest 60, the first biological sound propagation unit 20, and the housing 40 and attenuates noise components.

  Further, the second living body sound propagation unit 30 is required to have excellent sliding noise resistance and external environmental noise characteristics. Moreover, it is preferable that the acoustic impedance of the second biological sound propagation unit 30 has a large difference from the acoustic impedance of the biological sound. The hardness of the second biological sound propagation unit 30 is preferably small. It is preferable that the hardness is smaller than at least the first biological sound propagation unit 20. The material of the second biological sound propagation unit 30 is not particularly limited as long as it satisfies the above requirements, but preferred examples include a viscoelastic body or a rubber elastic body. Particularly preferable examples of the second living body sound propagation unit 30 include silicone rubber and urethane elastomer. The first biological sound propagation unit 20 and the second biological sound propagation unit 30 may contain an additive or the like as long as the characteristics are not affected.

  The housing 40 functions as the exterior of the biological sound collecting microphone 1. The space surrounded by the first biological sound propagation unit 20 and the housing 40 is filled with the second biological sound propagation unit 30, and the microphone unit 10 is embedded in the second biological sound propagation unit 30. The housing 40 has a cylindrical shape with an open bottom. As described above, the housing 40 is filled with the second biological sound propagation unit 30, and the microphone unit 10 is embedded therein.

  The material of the casing 40 is not particularly limited as long as it does not depart from the spirit of the present invention, but as an example, a highly vibration-damping metal such as aluminum, brass, stainless steel, ABS resin, PET resin, PC (polycarbonate) resin, etc. These resins are mentioned. The exterior appearance is not particularly limited as long as it is a shape suitable for auscultation. The shape of the body sound collecting microphone 1 that houses the microphone unit 10 is generally conical or cylindrical. The housing 40 may have a structure having a cavity inside or a structure without a cavity.

  Next, an example of a manufacturing method of the biological sound collecting microphone according to the first embodiment will be described. First, the housing 40 and the microphone unit 10 are prepared, and the main component and the curing agent of urethane elastomer (5 wt% with respect to the main agent) are mixed as the second biological sound propagation unit 20. Next, the microphone unit 10 is supported so as not to contact the inside of the housing 40, and the opening of the housing 40 on the signal line 50 side is temporarily sealed. Thereafter, the uncured second biological sound propagation unit 20 is filled from the opening side of the housing 40 in contact with the living body, and is left to cure at room temperature for 24 hours to form the second biological sound propagation unit 30.

  Next, a silicone elastomer main component and a curing agent (10 wt% with respect to the main component) are mixed as the first biological sound propagation unit 20. Then, the opening surface of the microphone unit 10 is injected so as to be filled with the silicone elastomer using the uncured first body sound propagation section 20, and left at room temperature for 24 hours to be cured, thereby allowing the first body sound propagation. Part 20 is formed. Through these steps, the biological microphone unit 10 is manufactured.

  The embedded position of the microphone unit 10 may be kept at the same height as the surface of the second biological sound propagation unit 30 or may be embedded in the second biological sound propagation unit 30. When the thickness of the second biological sound propagation unit 30 existing in the microphone unit 10 and the first biological sound propagation unit 20 is adjusted to within 0.5 mm, the microphone unit does not cause a decrease in sound pressure or a deterioration in frequency characteristics. 10 is preferable. The method for joining the first biological sound propagation unit 20 and the second biological sound propagation unit 30 is not particularly limited, but the adhesion force of the second biological sound propagation unit 30 is usually sufficient.

  According to the biological sound collecting microphone 1 according to the first embodiment, since the entire front side 21 of the first biological sound propagation unit 20 is brought into close contact with the skin surface of the biological chest 60, sound can be collected efficiently. That is, since the entire front side of the first living body sound propagation unit 20 can be brought into close contact with the body surface of the living body, noise can be efficiently removed. In addition, since the first body sound propagation unit 20 uses a plate-like member whose acoustic impedance characteristics are close to the acoustic impedance characteristics of the body sound collection region, the body sound can be efficiently conducted to the microphone unit 10. It becomes possible.

  Further, the second body sound propagation unit 30 is filled in a space defined by the first body sound propagation unit 20 and the housing 40, and a material having a Shore A hardness lower than that of the first body sound propagation unit 20 is used. Moreover, since the microphone unit 10 is embedded, the following effects can be obtained. That is, noise and environmental noise due to sliding with the patient during auscultation are unlikely to occur, and the attenuation of external noise can be increased to suppress noise mixing. As a result, the body sound can be efficiently conducted to the microphone unit 10.

  Furthermore, by using the first biological sound propagation unit 20 made of a material having a Shore A hardness of 40 or more, it is more effective at the interface between the biological chest 60 and the first biological sound propagation unit 20. It is possible to reduce the attenuation of biological sounds in the high sound range and collect biological sounds with high sensitivity and wide bandwidth. This is because by setting the Shore A hardness of the first living body sound propagation unit 20 to 40 or more, the Young's modulus and the sound speed can be more effectively maintained at substantially the same level as the living body chest 60 that is the subject. It is.

  Further, by filling the second biological sound propagation unit 30 with a large acoustic impedance difference between the biological chest 60, the first biological sound propagation unit 20, and the housing 40, the external noise can be attenuated more effectively. Can be increased, and noise contamination can be suppressed. In order to have such characteristics, the Shore A hardness of the second biological sound propagation unit 30 is preferably less than 40. The Shore A hardness of the second biological sound propagation unit 30 can be suitably applied even if it is the measurement lower limit. When the second biological sound propagation unit 30 has a low hardness, a large attenuation, and a low sound velocity, the sound other than the band of the biological sound is more effectively transmitted within the second biological sound propagation unit 30. Can be attenuated automatically. As a result, noise resistance can be improved. Moreover, the attenuation in the 2nd biological sound propagation part 30 can be made into the level which does not influence by shortening the transmission distance to the microphone unit 10 of the 1st biological sound propagation part 20. FIG.

[Second Embodiment]
Next, a living body sound collecting microphone incorporated in an electronic auscultation apparatus different from the first embodiment will be described. FIG. 3 is a schematic cross-sectional view of the biological sound collecting microphone 2 according to the second embodiment. The body sound collecting microphone 2 according to the second embodiment is for body sound collection according to the first embodiment, except that the shape of the housing 40a and the shape of the filling part of the second body sound propagation unit 30a are different. Similar to a microphone.

  The biological sound collecting microphone 2 includes a microphone unit 10, a first biological sound propagation unit 20, a second biological sound propagation unit 30a, a housing 40a, a signal line 50, and the like. The inner space of the housing 40a has a structure in which the upper part of the cone is cut off. In other words, the internal space of the housing 40a is trapezoidal when viewed from the side. The internal space of the housing 40a is filled with the second biological sound propagation unit 30a, and the microphone unit 10 is embedded in the second biological sound propagation unit 30a.

  FIG. 4 shows a spectrum of heart sounds collected using the biological sound collecting microphone 2 according to the second embodiment. The scale on the vertical axis is a 2 kHz scale, and the scale on the horizontal axis is a 20 sec scale. As the first living body sound propagation unit 20, silicone rubber having a Shore A hardness of 50 and a thickness of 1 mm was used. Moreover, it was 1650 m / s when the speed of sound in the 1st body sound propagation part 20 was calculated | required. The speed of sound can be obtained by the laser Doppler method.

  When the frequency analysis of the heart sound is performed, it is understood that information up to the high sound range (up to 2 kHz) is obtained as shown in FIG. This indicates that a wider band can be achieved on the high sound range side than a conventional stethoscope.

  FIG. 9 shows a spectrum of heart sounds collected using the meat conduction microphone having the configuration of FIG. 7 according to the comparative example. The scale on the vertical axis is a 2 kHz scale, and the scale on the horizontal axis is a 20 sec scale. As a biological sound propagation part, the spectrum of heart sound is shown when the Shore A hardness is 5, the distance between the living body and the microphone unit 10, that is, the thickness of the silicone rubber at the part is 1 mm. FIG. 9 shows that not only the attenuation of the signal, particularly the high sound range, is large, but also the sound pressure of the entire band is lowered, and the attenuation is larger than necessary. This is because the sound velocity in the resin is 700 m / s, and the deterioration of the microphone unit characteristics is due to the large acoustic impedance difference between the first living body sound propagation unit 20 and the living body chest 60.

  FIG. 5A shows the result of plotting the frequency characteristics of the measured sound of each sample by changing the Shore A hardness of the first biological sound propagation unit 20 in the biological sound collecting microphone according to the second embodiment. As shown in FIG. 5B, the low-frequency side frequency and the high-frequency range frequency shown in the figure indicate the frequencies on the low-frequency side and high-frequency side of the sound pressure that is −10 dB from the maximum sound pressure peak. . When the Shore A hardness is 40 or more, the low-frequency range frequency is shifted to the low-frequency range, the high-frequency range frequency is shifted to the high-frequency range, and the bandwidth is increased. It was found that the characteristics greatly affected. Therefore, the Shore A hardness of the first biological sound propagation unit 20 is preferably 40 or more, and the Shore A hardness of the second biological sound propagation unit 3 is preferably less than 40.

  From FIG. 5 (a), it can be seen that the body sound generated from the living body chest can be collected and analyzed in a wide band with higher sensitivity than the conventional stethoscope as well as the meat conduction microphone. And it can be expected to be used as a body sound collection microphone that can be used for early detection of hidden diseases.

  According to the biological sound collecting microphone and the electronic auscultation apparatus according to the second embodiment, the same effects as in the first embodiment can be obtained.

[Third Embodiment]
FIG. 6 is a schematic cross-sectional view of the biological sound collecting microphone 3 according to the third embodiment. The biological sound collecting microphone 3 according to the third embodiment is the same as the second biological sound except that the shape of the first biological sound propagation unit 20b and the filling region of the filling part of the second biological sound propagation unit 30b are different. This is the same as the biological sound collecting microphone according to the embodiment.

  The biological sound collection microphone 3 includes a first biological sound propagation unit 20b, a second biological sound propagation unit 30b, a housing 40b, a signal line 50, and the like at a position facing the microphone unit 10. The first biological sound propagation unit 20 b is provided at a position where it is opposed to the microphone unit 10. The second body sound propagation unit 30b is filled in the internal space of the housing 40b so as to surround the outer peripheral region of the first body sound propagation unit 20b. That is, in the third embodiment, in addition to the first biological sound propagation unit 20b and the housing 40b, the second biological sound propagation unit 30b is also in close contact with the body surface of the biological body.

  For the first biological sound propagation unit 20b whose main function is propagation of biological sound, a material such as urethane elastomer (relatively low adhesion) having a close acoustic impedance and a soft composition of the human body is adopted, and the second The living body sound propagation unit 30b preferably employs a material such as urethane elastomer having higher adhesion (adhesion), giving priority to adhesion to the skin. In other words, the second biological sound propagation unit 30b having a softer adhesiveness (solid mounting property) than the first biological sound propagation unit 20b is also provided with a skin adhesive portion. That is, a high adhesion force to the skin is used by using the second body sound propagation unit 30 with a high adhesion force (sturdiness) to the skin and the first body sound propagation unit 20 with a high propagation efficiency of the body sound. And intrusion of noise from the gap between the living body sound collecting microphone 1 and the skin can be prevented more reliably. In addition, in the above, although the example of the urethane elastomer was described, it is the same also when using another raw material.

  According to 3rd Embodiment, it becomes possible to make compatible the high adhesive force with respect to skin, and the high propagation efficiency of the body sound in a body sound conduction part by the said structure. As a result, in a state where the skin adhesive portion is in close contact with the skin surface, the contact surface with the skin surface in the first living body sound propagation portion 20b is more closely attached (adsorbed) to the skin surface. As a result, it is possible to more reliably prevent noise from entering the microphone unit 10 through the gap between the biological sound collecting microphone 3 and the skin.

  Further, according to the biological sound collecting microphone and the electronic auscultation apparatus according to the third embodiment, since the first biological sound propagation unit is provided in a region opposed to the microphone, the same as in the first embodiment. The effect of can be obtained.

  The present invention can be suitably applied to a body sound collecting microphone that collects body sound conducted through a living body. Further, the present invention can be suitably applied to an electronic auscultation apparatus incorporating the living body sound collecting microphone. In particular, it is suitable for a body sound collecting microphone and an electronic auscultation apparatus that collect body sounds such as heart sounds, lung sounds, breath sounds, blood flow sounds, peristaltic sounds, swallowing sounds and the like conducted from the human chest.

1, 2, 3 Microphone 10 for collecting body sound Microphone unit 20 First body sound propagation unit 21 Front surface 22 Back surface 30 Second body sound propagation unit 40 Housing 50 Signal line 60 Body chest

Claims (8)

A body sound collecting microphone for collecting body sounds,
A microphone unit that converts biological sound into an electrical signal;
A housing for housing the microphone unit;
It functions as a living body sound conducting unit for the microphone unit, its surface is in close contact with the body surface of the subject, its back surface is in contact with or close to the microphone unit, and is disposed at least opposite to the microphone unit. A first biological sound propagation unit;
A second living body that is made of a material having a Shore A hardness lower than that of the first living body sound propagation unit, is filled in a space defined by the housing and the first living body sound propagation unit, and embeds a microphone unit. A sound propagation part;
A microphone for collecting body sound, comprising:   The body sound collecting microphone according to claim 1, wherein the first body sound propagation unit has a Shore A hardness of 40 or more.   The microphone for collecting body sound according to claim 1 or 2, wherein the second body sound propagation part has a Shore A hardness of less than 40.   The body sound collection microphone according to claim 1, wherein the first body sound propagation unit is a viscoelastic body or a rubber elastic body.   5. The biological sound collection microphone according to claim 1, wherein the second biological sound propagation unit is a viscoelastic body or a rubber elastic body.   The living body sound collecting microphone according to claim 1, wherein the first living body sound propagation unit is made of silicone rubber or urethane elastomer.   The biological sound collecting microphone according to claim 1, wherein the second biological sound propagation unit is made of silicone rubber or urethane elastomer.   An electronic auscultation device incorporating the body sound collection microphone according to claim 1.