Noise reduction devices

Abstract

To provide a noise reduction device that ensures ventilation while effectively reducing noise. [Solution] The sound-reducing device 100 includes a first sound guide path 22 that extends in a straight line and into which the sound emitted from the wearer enters through a first opening (through hole 12 and through hole 21a), and a second sound guide path 23 that surrounds the first sound guide path 22, has a longer sound guide distance than the first sound guide path 22, and into which the sound emitted from the wearer enters through a second opening (through hole 14 and through hole 21b). At a predetermined merging position of the sound emitted from the wearer guided by the first sound guide path 22 and the sound emitted from the wearer guided by the second sound guide path 23, the sound emitted from the first sound guide path 22 and the sound emitted from the second sound guide path 23 are made to interfere with each other.

Description

Technical Field

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[0001] The present invention relates to a sound attenuation device.

Background Art

[0002] Conventionally, a mask that can obtain an attenuation effect (sound attenuation effect) of sound emitted from a person's mouth during a call in a public space or the like is known (for example, Patent Document 1).

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The mask described in Patent Document 1 has a configuration in which the ventilation path for the speaker's breathing is made longer, thereby attenuating the speaker's voice leaking to the outside through the ventilation path. Therefore, there is a problem that the speaker feels short of breath when using it. On the other hand, when the ventilation path is set to a thickness and length that the speaker does not feel short of breath and can easily speak, and a configuration that can ensure air permeability is adopted, problems such as insufficient sound attenuation effect occur.

[0005] Therefore, an object of the present invention is to provide a sound attenuation device that can ensure air permeability and effectively attenuate sound.

Means for Solving the Problems

[0006] The sound-reducing device of the present invention comprises a first sound guide path that extends in a straight line and into which the sound emitted from the wearer is incident through a first opening, and a second sound guide path that surrounds the first sound guide path, has a longer sound-guiding distance than the first sound guide path, and into which the sound emitted from the wearer is incident through a second opening, and interferes with the sound emitted from the first sound guide path and the sound emitted from the second sound guide path at a predetermined confluence point of the sound emitted from the first sound guide path and the sound emitted from the second sound guide path.

[0007] Furthermore, the noise reduction device of the present invention comprises a first unit and a second unit detachably attached to the first unit by a detachable mechanism, wherein the first unit comprises a first sound guide path extending in a straight line, through which the sound emitted from the wearer enters from a first opening, and a second sound guide path provided so as to surround the first sound guide path, having a longer sound guide distance than the first sound guide path, through which the sound emitted from the wearer enters from a second opening, wherein the second unit comprises a third sound guide path extending in a straight line, through which the sound emitted from the wearer via the first unit enters from a third opening, and a third sound guide path provided so as to surround the third sound guide path The device comprises a fourth sound guide, which is provided in the same location and has a longer sound guide distance than the third sound guide, and through which the sound emitted from the wearer via the first unit enters the fourth opening, wherein the third and fourth openings are provided at the location where the attachment / detachment mechanism is provided, and at the location where the attachment / detachment mechanism is provided, the sound emitted by the first sound guide and the sound emitted by the second sound guide interfere with each other, and at a predetermined confluence point of the sound emitted by the third sound guide and the sound emitted by the fourth sound guide, the sound emitted by the third sound guide and the sound emitted by the fourth sound guide interfere with each other. [Effects of the Invention]

[0008] According to the present invention, it is possible to ensure breathability while effectively reducing noise. [Brief explanation of the drawing]

[0009] [Figure 1]This figure shows an example of the use of a noise reduction device according to the first embodiment. [Figure 2] This is a perspective view showing the external appearance of the noise reduction device according to the first embodiment, including the side in the positive Y-axis direction. [Figure 3] This is a perspective view showing the external appearance of the protective section, including the negative Y-axis side. [Figure 4] This is a perspective view showing the appearance of the first unit, including the negative Y-axis side. [Figure 5] This is a cross-sectional view of the sound-reducing device according to the first embodiment, when cut by the YZ plane passing through the center in the X-axis direction. [Figure 6] This is a schematic diagram of the interior of the first unit as viewed from the positive Y-axis direction. [Figure 7] This figure shows an example of the use of a noise reduction device according to the second embodiment. [Figure 8] This is a perspective view showing the appearance of the noise reduction device according to the second embodiment, including the side in the positive Y-axis direction. [Figure 9] This is a perspective view showing the appearance of the second unit, including the negative Y-axis side. [Figure 10] This is a cross-sectional view of the sound-reducing device according to the second embodiment, when cut through the YZ plane passing through the center in the X-axis direction. [Figure 11] This is a schematic diagram of the inside of the second unit as viewed from the positive Y-axis direction. [Figure 12] This is a front view of the first unit according to the third embodiment, as seen from the positive Y-axis direction. [Figure 13] This is a front view of the first unit according to the third embodiment, as seen from the positive Y-axis direction. [Modes for carrying out the invention]

[0010] <First Embodiment> Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. As shown in Figure 1, the noise reduction device 100 according to this embodiment is attached to the user's mouth and covers the user's mouth. The noise reduction device 100 is for reducing sound, including the voice emitted by the user. The noise reduction device 100 is equipped with a microphone 13 (see Figure 3) and collects sound using the microphone. Therefore, the noise reduction device 100 can collect sound using the microphone 13 so that the voice emitted by the user is not heard by people around it. For example, when conducting a remote meeting in an office or at home, the noise reduction device 100 can reduce the amount of sound emitted by the user that is heard by people around it, thereby preventing the content of the conversation from being known to people around it or causing discomfort to people around it.

[0011] The sound-reducing device 100 of this embodiment may be worn inside the cover mask 200, near the user's mouth. This reduces the visual discomfort caused by wearing the sound-reducing device 100. If the cover mask 200 is made of a material with high sound-insulating properties (thick cloth, rubber sheet layer, etc.), using the cover mask 200 together with the sound-reducing device 100 can further reduce noise. Furthermore, if the cover mask 200 is made of a breathable material (mesh, non-woven fabric, etc.), comfort can be obtained when using the cover mask 200. The sound-reducing device 100 may be held by the user and worn near their mouth, or it may have a band or the like for attaching it to the user's head.

[0012] The sound reduction device 100 includes a protection part 10 and a first unit 20 attached to the protection part 10. The protection part 10 is provided at a part of the sound reduction device 100 that is worn in the user's mouth. The protection part 10 is formed of various relatively soft materials with low hardness such as silicon. As shown in FIGS. 2 and 3, the protection part 10 has a bottomed cylindrical shape, and a cross-section parallel to the XZ plane is elliptical. As shown in FIG. 5, the protection part 10 has a flat bottom part 10a parallel to the XZ plane, and a mouth part 10b that is arranged on the negative Y-axis side from the peripheral edge of the bottom part 10a and extends in the negative Y-axis direction, and the pipe diameter becomes narrower as the position in the negative Y-axis direction. The mouth part 10b has an opening 11 at the end on the negative Y-axis side. The opening 11 is arranged at a position surrounding the user's mouth when the sound reduction device 100 is worn in the user's mouth. That is, when the sound reduction device 100 is worn in the user's mouth, the user's mouth is arranged in the opening 11 of the protection part 10 and covered by the sound reduction device 100.

[0013] A through hole 12 that penetrates the bottom part 10a in the Y-axis direction and communicates with the outside of the sound reduction device 100 through the first unit 20 is provided in the bottom part 10a. The through hole 12 is provided at approximately the center in the X-axis direction and approximately the center in the Z-axis direction of the bottom part 10a. Further, as shown in FIG. 3, a through hole 14 that penetrates the bottom part 10a in the Y-axis direction and communicates with the outside of the sound reduction device 100 through the first unit 20 is provided in the bottom part 10a. The through hole 14 is provided adjacent to the through hole 12 at approximately the center in the Z-axis direction and on the positive X-axis side of the through hole 12 in the bottom part 10a. Further, a microphone 13 for collecting sound including the sound emitted by the user wearing the sound reduction device 100 is provided in the bottom part 10a. The microphone 13 is connected to a signal processing circuit and a communication IF (Interface) not shown, and the processing result signal-processed by the signal processing circuit may be transmitted to an external device by the communication IF.

[0014] The first unit 20 has an elliptical cylindrical shape, with an elliptical cross-section parallel to the XZ plane. The first unit 20 comprises a flat first surface member 21 located on the negative Y-axis side and parallel to the XZ plane, and a flat second surface member 24 located on the positive Y-axis side and parallel to the XZ plane. The first surface member 21 and the second surface member 24 have substantially the same shape as the bottom 10a in the XZ plane. As shown in Figure 6, the first unit 20 comprises a first sound conductor 22, a second sound conductor 23, and a partition wall 25 inside. The partition wall 25 is provided between the first surface member 21 and the second surface member 24 in the Y-axis direction, and forms the first sound conductor 22 and the second sound conductor 23 by partitioning the internal space of the first unit 20.

[0015] As shown in Figures 4 and 5, the first surface member 21 is provided with a through-hole 21a that penetrates the first surface member 21 in the Y-axis direction and communicates with the first sound guide path 22. The through-hole 21a is located approximately at the center of the first surface member 21 in the X-axis direction and approximately at the center in the Z-axis direction. The through-hole 21a is located in a position that overlaps with the through-hole 12 in the X-axis direction and Z-axis direction and communicates with the through-hole 12. The through-hole 12 and the through-hole 21a are collectively referred to as the first opening. Furthermore, as shown in Figure 4, the first surface member 21 is provided with a through-hole 21b that penetrates the first surface member 21 in the Y-axis direction and communicates with the second sound guide path 23. The through-hole 21b is located in the first surface member 21 on the positive X-axis side than the through-hole 21a and is located approximately at the center in the Z-axis direction, adjacent to the through-hole 21a. The through-hole 21b is located in a position that overlaps with the through-hole 14 in the X-axis and Z-axis directions, and is in communication with the through-hole 14. The through-hole 14 and the through-hole 21b together are referred to as the second opening.

[0016] As shown in Fig. 2, the second face member 24 is provided with a through hole 24a that penetrates the second face member 24 in the Y-axis direction and communicates with the first sound guide path 22. The through hole 24a is provided at a substantially central position in the X-axis direction and a substantially central position in the Z-axis direction of the second face member 24. The through hole 24a is provided at a position overlapping the through hole 12 and the through hole 21a in the X-axis direction and the Z-axis direction. Further, the second face member 24 is provided with a through hole 24b that penetrates the second face member 24 in the Y-axis direction and communicates with the second sound guide path 23. The through hole 24b is provided adjacent to the through hole 24a at a position on the negative X-axis side of the through hole 24a in the second face member 24 and at a substantially central position in the Z-axis direction.

[0017] The first sound guide path 22 is provided at a substantially central position in the X-axis direction and a substantially central position in the Z-axis direction within the first unit 20. Note that the first sound guide path 22 may be provided at a position other than the center in the X-axis direction or the center in the Z-axis direction within the first unit 20. The first sound guide path 22 is a hollow tube with a circular internal cross-section that extends linearly in the Y-axis direction and penetrates the first unit 20 in the Y-axis direction. The inner diameter of the first sound guide path 22 is substantially the same as the inner diameter of the through hole 12 of the protection part 10, the inner diameter of the through hole 21a of the first face member 21, and the inner diameter of the through hole 24a of the second face member 24. The first sound guide path 22 is connected to the through hole 21a at the end on the negative Y-axis side and is connected to the through hole 24a at the end on the positive Y-axis side. The first sound guide distance L1, which is the sound guide distance of the first sound guide path 22, is the distance from the end on the negative Y-axis side to the end on the positive Y-axis side of the first sound guide path 22.

[0018] The first unit 20 is provided with a rib 26 on the Y-axis positive side of the second surface member 24. The rib 26 is attached to the approximate center in the Z-axis direction of the Y-axis positive side of the second surface member 24 and protrudes in an annular shape toward the Y-axis positive direction. At least the through holes 24a and 24b of the second surface member 24 are located in the space 26a enclosed by the rib 26 of the first embodiment. The inner diameter of the rib 26 of the first embodiment is large enough to accommodate at least the through holes 24a and 24b of the second surface member 24 in the XZ plane. The Y-axis positive side end of the rib 26 is open to the outside air. In the first embodiment, the first unit 20 does not need to be provided with a rib 26.

[0019] The space 10c enclosed by the protective part 10, the through hole 12 in the bottom part 10a, the through hole 21a in the first surface member 21, the first sound guide path 22, the through hole 24a in the second surface member 24, the space 26a enclosed by the rib 26, and the space outside the sound-reducing device 100 are in communication. This allows the user to release the air blown out from their mouth into the space outside the sound-reducing device 100 while the protective part 10 of the sound-reducing device 100 is tightly pressed against the area around their mouth. In other words, when the user is wearing the sound-reducing device 100 and speaking, the air blown out from the user's mouth can be released into the space outside the sound-reducing device 100, thus reducing the feeling of breathlessness the user experiences while wearing the sound-reducing device 100. Furthermore, the through-hole 12 in the bottom 10a, the through-hole 21a in the first surface member 21, the first sound guide path 22, and the through-hole 24a in the second surface member 24 are arranged linearly in the Y-axis direction. Therefore, when the user is speaking, the air blown out from the user's mouth can be released into the space outside the sound-reducing device 100 through the linearly arranged ventilation passages (through-hole 12, through-hole 21a, first sound guide path 22, and through-hole 24a). Thus, the feeling of breathlessness when the user is wearing the sound-reducing device 100 can be further reduced.

[0020] The second sound guide path 23 is provided within the first unit 20 so as to surround the first sound guide path 22 and along a virtual plane whose normal direction is the direction along the extension direction of the first sound guide path 22. The direction along the extension direction of the first sound guide path 22 is the Y-axis direction. The virtual plane whose normal direction is the Y-axis direction is a plane parallel to the XZ plane. One end 23a of the second sound guide path 23 is located on the positive X-axis side of the first sound guide path 22 and is located approximately at the center in the Z-axis direction. The one end 23a of the second sound guide path 23 is located adjacent to the first sound guide path 22 in the X-axis direction. One end 23a of the second sound guide path 23 is connected to a through-hole 21b of the first surface member 21, and the internal space of the second sound guide path 23 communicates with the space 10c enclosed by the protective part 10 via the through-hole 21b of the first surface member 21 and the through-hole 14 of the bottom part 10a. The other end 23b of the second sound guide path 23 is located on the negative X-axis side of the first sound guide path 22 and is approximately at the center in the Z-axis direction. The other end 23b of the second sound guide path 23 is located adjacent to the first sound guide path 22 in the X-axis direction. The other end 23b of the second sound guide path 23 is connected to a through-hole 24b of the second surface member 24, and the internal space of the second sound guide path 23 communicates with the space outside the sound reduction device 100 via the through-hole 24b of the second surface member 24. The second sound guiding distance L2, which is the sound guiding distance of the second sound guiding path 23, is the distance from one end 23a to the other end 23b of the second sound guiding path 23, and is longer than the first sound guiding distance L1. As described above, the space 10c surrounded by the protective part 10, the through hole 14 in the bottom part 10a, the through hole 21b in the first surface member 21, the second sound guiding path 23, the through hole 24b in the second surface member 24, the space 26a surrounded by the rib 26, and the space outside the sound reducing device 100 are in communication.

[0021] When the sound-reducing device 100 is attached to the user's mouth and the user makes a sound, the sound enters the first sound guide 22 from the negative Y-axis direction through the first opening (through-holes 12 and 21a). The sound then passes through the first sound guide 22 and exits the sound-reducing device 100 through the through-hole 24a. Furthermore, the sound made by the user enters the second sound guide 23 from one end 23a through the second opening (through-holes 14 and 21b). The sound then passes through the second sound guide 23 and exits the sound-reducing device 100 from the other end 23b through the through-hole 24b. In Figure 6, the direction of the sound passing through the second sound guide 23 is indicated by arrow A. The first sound wave, which is a sound wave of sound emitted from the through-hole 24a after passing through the first sound guide 22, and the second sound wave, which is a sound wave of sound emitted from the through-hole 24b after passing through the second sound guide 23, merge in the space 26a enclosed by the rib 26. Since the second sound distance L2 is longer than the first sound distance L1, the sound waves passing through the second sound guide 23 vibrate more than the sound waves passing through the first sound guide 22, and there is a phase difference between the second sound wave and the first sound wave. At the point where the first and second sound waves merge, the first sound wave and the phase-shifted second sound wave interfere with each other, causing the sound in the frequency range corresponding to the phase difference in the first sound wave to cancel each other out. As a result, at the point where the first and second sound waves merge, the sound with a peak in that frequency range in the first sound wave is attenuated and emitted.

[0022] The first guiding distance L1 and the second guiding distance L2 are set to values ​​that satisfy the following equation (1). f1 = V / 2·(L2-L1) ···(1) f1: Frequency at which sound is reduced from the user's voice. V: velocity of sound When the above equation (1) is satisfied, the first unit 20 can reduce the sound with a peak at frequency f1 in response to the voice emitted by the user.

[0023] <Second Embodiment> Next, a second embodiment of the present invention will be described. In the second embodiment, the same reference numerals are used for components as in the first embodiment, and their descriptions are omitted. As shown in Figure 7, the noise reduction device 100 of the second embodiment comprises a protective section 10, a first unit 20, and a second unit 40 that is detachably attached to the first unit 20. The noise reduction device 100 of the second embodiment is constructed by connecting the second unit 40, the first unit 20, and the protective section 10 in order from the positive Y-axis direction.

[0024] The second unit 40 has an elliptical cylindrical shape, with an elliptical cross-section parallel to the XZ plane. As shown in Figure 10, the second unit 40 comprises a flat third surface member 41 located on the negative Y-axis side and parallel to the XZ plane, and a flat fourth surface member 44 located on the positive Y-axis side and parallel to the XZ plane. The third surface member 41 and the fourth surface member 44 are smaller in shape than the bottom 10a, the first surface member 21, and the second surface member 24 in the X-axis and Z-axis directions. The second unit 40 contains a third sound guide 42, a fourth sound guide 43, and a partition wall 45 inside. The partition wall 45 is provided between the third surface member 41 and the fourth surface member 44 in the Y-axis direction, and forms the third sound guide 42 and the fourth sound guide 43 by partitioning the internal space of the second unit 40.

[0025] As shown in Figures 9 and 10, the third surface member 41 is provided with a third opening 41a that penetrates the third surface member 41 in the Y-axis direction and communicates with the third sound guide path 42. The third opening 41a is located approximately at the center of the third surface member 41 in the X-axis direction and approximately at the center in the Z-axis direction. The third opening 41a is located in a position that overlaps with the through hole 24a of the second surface member 24 in the X-axis direction and the Z-axis direction. Furthermore, as shown in Figure 9, the third surface member 41 is provided with a fourth opening 41b that penetrates the third surface member 41 in the Y-axis direction and communicates with the fourth sound guide path 43. The fourth opening 41b is located adjacent to the third opening 41a in the third surface member 41, on the positive X-axis side of the third opening 41a, and approximately at the center in the Z-axis direction. The fourth opening 41b is located in a position that overlaps with the through hole 21b of the first surface member 21 in the X-axis direction and the Z-axis direction.

[0026] The third face member 41 has an annular recess 47 into which the rib 26 is inserted. The recess 47 is provided with a retaining structure (not shown) that prevents the rib 26 from coming out of the recess 47. By inserting the rib 26 into the recess 47, the second unit 40 can be attached to the first unit 20. On the other hand, by removing the rib 26 from the recess 47, the second unit 40 can be removed from the first unit 20. In the second embodiment, the recess 47 and the rib 26 function as an attachment / detachment mechanism. In the space 26a surrounded by the rib 26 in the second embodiment, at least the through holes 24a and 24b of the second face member 24 and the third opening 41a and fourth opening 41b of the third face member 41 are located. In the second embodiment, the inner diameter of the rib 26 is large enough to accommodate at least the through holes 24a and 24b of the second face member 24 and the fourth opening 41b of the third face member 41 in the XZ plane.

[0027] As shown in Figures 8 and 10, the fourth face member 44 is provided with a through-hole 44a that penetrates the fourth face member 44 in the Y-axis direction and communicates with the third sound guide 42. The through-hole 44a is located approximately at the center of the fourth face member 44 in the X-axis direction and approximately at the center in the Z-axis direction. The through-hole 44a is located in a position that overlaps with the through-hole 24a of the second face member 24 and the third opening 41a of the third face member 41 in the X-axis and Z-axis directions. Furthermore, as shown in Figure 8, the fourth face member 44 is provided with a through-hole 44b that penetrates the fourth face member 44 in the Y-axis direction and communicates with the fourth sound guide 43. The through-hole 44b is located in the fourth face member 44 on the negative X-axis side than the through-hole 44a and is located approximately at the center in the Z-axis direction, adjacent to the through-hole 44a. The through-hole 44b is provided in a position that overlaps with the through-hole 24b of the second surface member 24 in the X-axis direction and the Z-axis direction.

[0028] The third sound guide 42 is provided within the second unit 40 at approximately the center of the second unit 40 in the X-axis direction and approximately the center in the Z-axis direction. The third sound guide 42 may also be provided within the second unit 40 at a location other than the center in the X-axis direction or the center in the Z-axis direction. The third sound guide 42 is a hollow tube with a circular internal cross-section that extends linearly in the Y-axis direction and penetrates the second unit 40 in the Y-axis direction. The inner diameter of the third sound guide 42 is approximately the same as the inner diameter of the through-hole 12 of the protective part 10, the inner diameter of the through-hole 21a of the first surface member 21, the inner diameter of the first sound guide 22, the inner diameter of the through-hole 24a of the second surface member 24, the inner diameter of the third opening 41a of the third surface member 41, and the inner diameter of the through-hole 44a of the fourth surface member 44. The third sound guide path 42 is connected to the third opening 41a at its end on the negative Y-axis side and to the through hole 44a at its end on the positive Y-axis side. The third sound guide distance L3, which is the sound guide distance of the third sound guide path 42, is the distance from the end on the negative Y-axis side to the end on the positive Y-axis side of the third sound guide path 42.

[0029] The second unit 40 is provided with a rib 46 on the Y-axis positive side of the fourth face member 44. The rib 46 is attached to the approximate center in the Z-axis direction of the Y-axis positive side of the fourth face member 44 and protrudes in an annular shape toward the Y-axis positive direction. At least the through holes 44a and 44b of the fourth face member 44 are located in the space 46a enclosed by the rib 46. The inner diameter of the rib 46 is large enough to accommodate at least the through holes 44a and 44b of the fourth face member 44 in the XZ plane. The Y-axis positive side end of the rib 46 is open to the outside air. Note that the second unit 40 does not necessarily have to be provided with a rib 46.

[0030] The space 10c enclosed by the protective part 10 is in communication with the space outside the sound-reducing device 100 via the space inside the first unit 20, the third opening 41a of the third surface member 41, the third sound guide path 42, the through hole 44a of the fourth surface member 44, and the space 46a enclosed by the rib 46. This allows the user to release the air blown out of their mouth into the space outside the sound-reducing device 100 while the protective part 10 of the sound-reducing device 100 is tightly pressed against their mouth. In other words, when the user is wearing the sound-reducing device 100 and speaking, the air blown out of the user's mouth can be released into the space outside the sound-reducing device 100, thus reducing the feeling of breathlessness the user experiences while wearing the sound-reducing device 100. Furthermore, the through-hole 12 in the bottom 10a, the through-hole 21a in the first surface member 21, the first sound guide path 22, the through-hole 24a in the second surface member 24, the space 26a surrounded by the rib 26, the third opening 41a in the third surface member 41, the third sound guide path 42, and the through-hole 44a in the fourth surface member 44 are arranged linearly in the Y-axis direction. Therefore, when the user is speaking, the air blown out from the user's mouth can be released into the space outside the sound-reducing device 100 through the linearly arranged ventilation passages (through-hole 12, through-hole 21a, first sound guide path 22, through-hole 24a, rib 26, third opening 41a, third sound guide path 42, and through-hole 44a). Therefore, the feeling of breathlessness when the user is wearing the sound-reducing device 100 can be further reduced.

[0031] The fourth sound guide 43 is provided within the second unit 40 so as to surround the third sound guide 42 and along a virtual plane whose normal direction is the direction along the extension direction of the third sound guide 42. The direction along the extension direction of the third sound guide 42 is the Y-axis direction. The virtual plane whose normal direction is the Y-axis direction is a plane parallel to the XZ plane. One end 43a of the fourth sound guide 43 is located on the positive X-axis side of the third sound guide 42 and is located approximately at the center in the Z-axis direction. One end 43a of the fourth sound guide 43 is located adjacent to the third sound guide 42 in the X-axis direction. One end 43a of the fourth sound guide 43 is connected to the fourth opening 41b of the third surface member 41, and the space inside the fourth sound guide 43 is in communication with the space 10c enclosed by the protective part 10 via the fourth opening 41b of the third surface member 41 and the space inside the first unit 20. The other end 43b of the fourth sound guide 43 is located on the negative X-axis side of the third sound guide 42 and is positioned approximately at the center in the Z-axis direction. The other end 43b of the fourth sound guide 43 is positioned adjacent to the third sound guide 42 in the X-axis direction. The other end 43b of the fourth sound guide 43 is connected to the through hole 44b of the fourth surface member 44, and the internal space of the fourth sound guide 43 communicates with the external space of the sound reduction device 100 through the through hole 44b of the fourth surface member 44. The fourth sound guide distance L4, which is the sound guide distance of the fourth sound guide 43, is the distance from one end 43a to the other end 43b of the fourth sound guide 43, and is longer than the third sound guide distance L3. In the second embodiment, the fourth sound guide distance L4 is shorter than the second sound guide distance L2. As described above, the space 10c enclosed by the protective part 10 is in communication with the space outside the sound-reducing device 100 via the space inside the first unit 20, the fourth opening 41b of the third surface member 41, the fourth sound guide path 43, the through hole 44b of the fourth surface member 44, and the space 46a enclosed by the rib 46.

[0032] When the sound-reducing device 100 of the second embodiment is attached to the user's mouth and the user makes a sound, the sound enters the interior of the first unit 20 from the first and second openings, similar to the first embodiment. The first sound wave and the second sound wave then merge in the space 26a surrounded by the rib 26, and at this merging point, the first sound wave and the second sound wave, which is out of phase, interfere with each other, causing the sound in the frequency range corresponding to the phase difference in the first sound wave to cancel each other out. As a result, at this merging point, the sound with the peak in that frequency range in the first sound wave is reduced and emitted. Next, the sound, with the sound with the peak in the frequency range corresponding to the phase difference between the first sound wave and the second sound wave reduced, enters the interior of the third sound guide 42 from the negative Y-axis direction side through the third opening 41a from the space 26a surrounded by the rib 26. The incoming sound then passes through the inside of the third sound guide 42 and is emitted from the through-hole 44a to the outside of the sound reduction device 100. Furthermore, the sound, which has been attenuated with a peak in the frequency range corresponding to the phase difference between the first sound wave and the second sound wave, is incident on the interior of the fourth sound guide 43 from one end 43a of the fourth sound guide 43 through the fourth opening 41b from the space 26a enclosed by the rib 26. The incident sound then passes through the interior of the fourth sound guide 43 and is emitted to the outside of the sound reduction device 100 from the other end 43b through the through hole 44b. In Figure 11, the direction of the sound passing through the interior of the fourth sound guide 43 is indicated by arrow B. The third sound wave, which is the sound wave of the sound emitted from the through hole 44a after passing through the interior of the third sound guide 42, and the fourth sound wave, which is the sound wave of the sound emitted from the through hole 44b after passing through the interior of the fourth sound guide 43, merge in the space 46a enclosed by the rib 46. Since the fourth sound guiding distance L4 is longer than the third sound guiding distance L3, the sound waves passing through the fourth sound guiding path 43 vibrate more than the sound waves passing through the third sound guiding path 42, and there is a phase difference between the fourth sound wave and the third sound wave. At the point where the third and fourth sound waves merge, the third sound wave and the phase-shifted fourth sound wave interfere with each other, causing the sound in the frequency range corresponding to that phase difference in the third sound wave to cancel each other out. As a result, at the point where the third and fourth sound waves merge, the sound with a peak in that frequency range in the third sound wave is attenuated and emitted.

[0033] The third and fourth guiding distances L3 and L4 are set to values ​​that satisfy the following equation (2). f2 = V / 2·(L4-L3) ···(2) f2: Frequency attenuation from the user's voice V: velocity of sound When both equation (1) and equation (2) above are satisfied, the first unit 20 can reduce the sound peaking at frequency f1, and the second unit 40 can reduce the sound peaking at frequency f2, in relation to the voice emitted by the user.

[0034] Furthermore, in the second embodiment of the sound-reducing device 100, by setting the third sound-guiding distance L3 and the fourth sound-guiding distance L4 such that the frequency f2 reduced by the second unit 40 and the frequency f1 reduced by the first unit 20 are different, the sound emitted by the user can be reduced over a wider frequency range than in the first embodiment of the sound-reducing device 100. In addition, compared to the first embodiment of the sound-reducing device 100, the distance from the sound incident through the through-hole 12 to the outside of the sound-reducing device 100 is longer by the length of the second unit 40 in the Y-axis direction. Therefore, by using the second embodiment of the sound-reducing device 100, a higher sound reduction effect can be obtained than when using the first embodiment of the sound-reducing device 100. When the user is wearing the second embodiment of the sound-reducing device 100 and is speaking, the air blown out from the user's mouth is released to the outside of the sound-reducing device 100 through a ventilation passage arranged linearly from the through-hole 12. In this case, the length of the ventilation passage through which the air blown out from the user's mouth passes is approximately the sum of the lengths of the first unit 20 and the second unit 40 in the Y-axis direction, for example, 5 cm. Therefore, the feeling of breathlessness when the user is wearing the sound-reducing device 100 of the second embodiment can be reduced.

[0035] As described above, since the frequency range attenuated by the sound-reducing device 100 of the first embodiment and the sound-reducing device 100 of the second embodiment are different, the sound-reducing device 100 of the first embodiment and the sound-reducing device 100 of the second embodiment can be used interchangeably depending on the pitch of the user's voice. For example, when a person with a relatively low voice (e.g., around 500 Hz) uses the sound-reducing device 100, sufficient sound reduction can be obtained by using the sound-reducing device 100 of the first embodiment. In this case, since the sound-reducing device 100 is smaller than the sound-reducing device 100 of the second embodiment, wearability can be improved and the appearance can be made better. Alternatively, when a person with a high-pitched voice (e.g., around 800 Hz), such as a child, a small person, or a woman, uses the sound-reducing device 100, sufficient sound reduction can be obtained by using the sound-reducing device 100 of the second embodiment, that is, the sound-reducing device 100 in which the second unit 40 and the first unit 20 are connected to the protective part 10. Furthermore, the noise reduction device 100 of the first embodiment and the noise reduction device 100 of the second embodiment can be used interchangeably depending on the frequency range to be reduced. For example, if you want to reduce particularly unpleasant sounds (e.g., 1.5 kHz or higher), using the noise reduction device 100 of the second embodiment will provide a sufficient noise reduction effect for particularly unpleasant sounds. Also, when playing games in your room and you want to enhance the noise reduction effect without worrying about appearance, using the noise reduction device 100 of the second embodiment will provide a sufficient noise reduction effect. Also, when teleworking in a cafe and speaking in a low voice, using the noise reduction device 100 of the first embodiment will provide a sufficient noise reduction effect.

[0036] <Third Embodiment> Next, a third embodiment of the present invention will be described. In the third embodiment, the same reference numerals are used for components similar to those in the first embodiment, and their descriptions are omitted. The first unit 20 of the sound-reducing device 100 of the third embodiment is configured to have a variable second sound-guiding distance L2, which is the sound-guiding distance of the second sound-guiding path 23. Specifically, the first unit 20 of the third embodiment has a telescopic structure and includes a movable part 26A that can slide in the negative X-axis direction from the state shown in Figure 12 to the state shown in Figure 13, and a movable part 26B that can slide in the positive X-axis direction. The movable parts 26A and 26B have the second sound-guiding path 23 inside. The second sound-guiding distance L2 of the first unit 20 in the state shown in Figure 13 is longer than the second sound-guiding distance L2 of the first unit 20 in the state shown in Figure 12. Therefore, the frequency f1 reduced by the first unit 20 in the state shown in Figure 13 is lower than the frequency f1 in the state shown in Figure 12. As described above, in the third embodiment, the frequency f1 attenuated by the first unit 20 can be adjusted by changing the length of the second sound conduction distance L2 by sliding the movable parts 26A and 26B. The first unit 20 in the third embodiment may also include a telescopic structure comprising a movable part that can slide in the negative X-axis direction and / or the negative Z-axis direction from the state shown in Figure 12, and a movable part that can slide in the positive X-axis direction and / or the positive Z-axis direction.

[0037] As described above, the sound-reducing device 100 according to this embodiment includes a first sound guide path 22 that extends in a straight line and into which the sound emitted from the wearer enters through a first opening (through-hole 12 and through-hole 21a), and a second sound guide path 23 that surrounds the first sound guide path 22, has a longer sound guide distance than the first sound guide path 22, and into which the sound emitted from the wearer enters through a second opening (through-hole 14 and through-hole 21b). At a predetermined merging point of the sound emitted by the first sound guide path 22 and the sound emitted by the second sound guide path 23, the sound emitted by the first sound guide path 22 and the sound emitted by the second sound guide path 23 are made to interfere with each other. Therefore, the air blown out with the sound into the space enclosed by the protective part 10 can be released into the space outside the sound-reducing device 100 via the straight first sound guide path 22, thus ensuring ventilation. Furthermore, sound entering the space enclosed by the protective section 10 is directed into the first sound guide path 22 and the second sound guide path 23, and the sound produced by the first sound guide path 22 and the sound produced by the second sound guide path 23 interfere with each other, thereby reducing the sound. This ensures ventilation while effectively reducing the sound.

[0038] In the sound reduction device 100 according to this embodiment, the second sound guide path 23 is provided along a virtual plane (a plane parallel to the XZ plane) whose normal direction is the direction along the extension direction of the first sound guide path 22 (the Y-axis direction). Therefore, the sound guiding distance of the second sound guide path 23 can be made variable by winding the second sound guide path 23 along a plane parallel to the XZ plane without changing the length of the first sound guide path 22 in the Y-axis direction.

[0039] In the sound reduction device 100 according to this embodiment, the sound guiding distance of the second sound guide path 23 can be adjusted by the fact that a part of the second sound guide path 23 is expandable and contractible in a direction along a virtual plane. Therefore, the sound guiding distance of the second sound guide path 23 can be easily adjusted. This makes it easy to adjust the frequency attenuated by the first unit 20.

[0040] The noise reduction device 100 according to this embodiment is equipped with a microphone 13 inside the housing. Therefore, the noise reduction device 100 can be used when conducting remote meetings in an office or at home, and can reduce the amount of the user's voice heard by those around them. This makes it possible to prevent the content of the conversation from being known to those around you, or to prevent causing discomfort to those around you.

[0041] The noise reduction device 100 according to this embodiment comprises a first unit 20 and a second unit 40 that is detachably attached to the first unit 20 by a detachable mechanism (rib 26 and recess 47). The first unit 20 comprises a first sound guide path 22 that extends linearly and into which the sound emitted from the wearer enters through a first opening (through hole 12 and through hole 21a), and a second sound guide path 23 that surrounds the first sound guide path 22, has a longer sound guide distance than the first sound guide path 22, and into which the sound emitted from the wearer enters through a second opening (through hole 14 and through hole 21b). The second unit 40 extends linearly and into which the sound emitted from the wearer via the first unit 20 enters through a third opening 41a. The device comprises a third sound guide 42, a fourth sound guide 43 which is provided so as to surround the third sound guide 42 and has a longer sound guide distance than the third sound guide 42, and into which the sound emitted from the wearer via the first unit 20 enters through the fourth opening 41b, the third opening 41a and the fourth opening 41b are provided at positions where the attachment / detachment mechanism is provided, the sound emitted by the first sound guide 22 and the sound emitted by the second sound guide 23 interfere at the positions where the attachment / detachment mechanism is provided, and the sound emitted by the third sound guide 42 and the sound emitted by the fourth sound guide 43 interfere at a predetermined confluence position of the sound emitted by the third sound guide 42 and the sound emitted by the fourth sound guide 43. Therefore, the air blown into the space enclosed by the protective unit 10 along with the sound can be released into the space outside the sound reduction device 100 via the linear first sound guide 22 and third sound guide 42, thus ensuring ventilation. Furthermore, the sound incident on the space enclosed by the protective unit 10 can be directed into the first sound guide 22 and second sound guide 23, and the sound guided by the first sound guide 22 and the sound guided by the second sound guide 23 can be made to interfere with each other, thereby reducing the sound. In addition, the sound reduced by the first unit 20 can be directed into the third sound guide 42 and fourth sound guide 43, and the sound guided by the third sound guide 42 and the sound guided by the fourth sound guide 43 can be made to interfere with each other, thereby further reducing the sound. This ensures ventilation while effectively reducing the sound.

[0042] The above embodiments are provided as specific examples to facilitate understanding of the invention, and the present invention is not limited to these embodiments. Various modifications and changes are possible without departing from the spirit of the invention. For example, in the above embodiments, the second sound guide path 23 is provided within the first unit 20 along a virtual plane (a plane parallel to the XZ plane) whose normal direction is the direction along the extension direction of the first sound guide path 22. Also, the fourth sound guide path 43 is provided within the second unit 40 along a virtual plane (a plane parallel to the XZ plane) whose normal direction is the direction along the extension direction of the third sound guide path 42. However, the invention is not limited to these, and the second sound guide path 23 and the fourth sound guide path 43 may have a curved shape that conforms to the shape of the user's face when the user is wearing the sound-reducing device 100. Furthermore, the first unit 20 may be configured to be detachable from the protective part 10, and the second unit 40 may be configured to be detachable from the protective part 10. In this case, only the second unit 40 may be attached to the protective part 10. Furthermore, although the noise reduction device 100 of the second embodiment is configured by connecting the second unit 40, the first unit 20 and the protective part 10 in order from the positive direction of the Y axis, it is not limited to this. The noise reduction device 100 may be configured by connecting the first unit 20, the second unit 40 and the protective part 10 in order from the positive direction of the Y axis. In addition, the noise reduction device 100 may include a third unit that reduces sounds in a different frequency range from the first unit 20 and the second unit 40 in response to the voice emitted by the user. In this case, the noise reduction device 100 is configured by linearly connecting the third unit and the first unit 20 and / or the second unit 40 to the protective part 10. Furthermore, the noise reduction device 100 may include a fourth unit that reduces sounds in a different frequency range from the first unit 20, the second unit 40 and the third unit. In this case, the fourth unit and the first unit 20, the second unit 40 and / or the third unit are linearly connected to the protective part 10 to form the sound-reducing device 100. Furthermore, in the above embodiment, the sound-reducing device 100 is formed in a shape that covers the wearer's mouth while exposing the nose, but the sound-reducing device 100 may be formed in a shape that covers both the wearer's mouth and nose.In this case, the protective part 10 should be formed so that it surrounds both the wearer's mouth and nose. [Explanation of Symbols]

[0043] 100...Sound reduction device, 12...Through hole (first opening), 14...Through hole (second opening), 21a...Through hole (first opening), 21b...Through hole (second opening), 22...First sound guide path, 23...Second sound guide path

Claims

1. A first sound guide path extends in a straight line, and the sound emitted from the wearer enters through a first opening, A second sound guide is provided so as to surround the first sound guide, has a longer sound guide distance than the first sound guide, and through which the sound emitted by the wearer enters the second opening. Equipped with, A sound reduction device that causes the sound guided by the first sound guide and the sound guided by the second sound guide to interfere with each other at a predetermined merging point of the two sound guides.

2. The sound-reducing device according to claim 1, wherein the second sound guide is provided along a virtual plane whose normal direction is the direction along the extension direction of the first sound guide.

3. The sound reducing device according to claim 2, wherein the second sound guide path is adjustable in terms of the distance of sound guided by a portion of the second sound guide path being expandable or contractible in a direction along the virtual plane.

4. The noise reduction device according to claim 1, comprising a microphone inside the housing.

5. The first unit and, A second unit is detachably attached to the first unit by a detachment mechanism, Equipped with, The first unit is, A first sound guide path extends in a straight line, and the sound emitted from the wearer enters through a first opening, The device comprises a second sound guide, which is provided so as to surround the first sound guide, has a longer sound guide distance than the first sound guide, and through which the sound emitted by the wearer is incident from the second opening, The second unit is, A third sound guide path extends in a straight line, and the sound emitted from the wearer via the first unit enters through the third opening, The device comprises a fourth sound guide, which is provided so as to surround the third sound guide, has a longer sound guide distance than the third sound guide, and through which the sound emitted from the wearer via the first unit enters the fourth opening, The third and fourth openings are located at the positions where the attachment / detachment mechanism is provided. At the position where the attachment / detachment mechanism is provided, the sound induced by the first sound guide path and the sound induced by the second sound guide path are made to interfere with each other. A sound reduction device that causes the sound guided by the third sound guide and the sound guided by the fourth sound guide to interfere with each other at a predetermined merging point of the third sound guide and the fourth sound guide.

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