Sound measuring device

Abstract

A sound measurer (100) includes: a light source (111) that emits laser light; a housing portion (120) that surrounds a prescribed space through which sound passes in a manner that intersects a direction of travel of the sound, and has at least one reflecting surface (1211a, 1211b) that faces the prescribed space; and a light receiving portion (115) that receives laser light that is multiply reflected by the at least one reflecting surface (1211a, 1211b). The at least one reflecting surface (1211a, 1211b) is configured to multiply reflect the laser light in the prescribed space in a manner that intersects the prescribed space when the prescribed space is viewed from the direction of travel of the sound.

Description

Technical Field

[0001] This disclosure relates to a sound measuring device. Background Technology

[0002] As a device for collecting sound waves propagating in the air and converting them into electrical signals, a plate-type microphone is known to cause sound waves to be incident on a diaphragm and to convert the minute vibrations excited in the diaphragm by the sound into electrical signals. However, plate-type microphones have difficulty detecting sounds above the mechanical resonant frequency of the diaphragm, so the upper limit of the frequency band of the sound that can be detected is limited to about 100 kHz.

[0003] On the other hand, optical microphones that utilize light, such as lasers, to measure minute and high-speed vibrations are known. For example, Patent Document 1 discloses a sound collection system in which a laser is directly propagated in a sound field, and a laser Doppler vibrometer is used to directly capture the change in refractive index in the air caused by the sound wave, thereby measuring the sound pressure. In the sound collection system described in Patent Document 1, the mechanical resonance of a vibrating plate is not used in the sound detection, so the upper limit of the frequency band of detectable sound can easily exceed 100 kHz.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-279259 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, the sound collection system described in Patent Document 1 has low sound pressure sensitivity.

[0009] Therefore, this disclosure provides a sound meter with improved sound pressure sensitivity.

[0010] Methods used to solve problems

[0011] A sound measuring device according to the present disclosure includes: a light source that emits laser light; a frame that surrounds a predetermined space through which the sound travels in a manner intersecting with the direction of sound travel and having at least one reflective surface facing the predetermined space; and a light-receiving portion that receives the laser light obtained by multiple reflections from the at least one reflective surface; wherein the at least one reflective surface is configured such that, when the predetermined space is viewed from the direction of sound travel, the laser light is intersected and reflected multiple times within the predetermined space.

[0012] Invention Effects

[0013] According to this disclosure, a sound meter with improved sound pressure sensitivity can be provided. Attached Figure Description

[0014] Figure 1 This diagram illustrates an example of the structure of a conventional optical microphone.

[0015] Figure 2 This is a diagram illustrating an example of the structure of a sound meter according to an embodiment.

[0016] Figure 3 It is Figure 2 The frame shown is a three-dimensional view viewed from an oblique angle.

[0017] Figure 4 It is used to explain Figure 2 A diagram showing an example of the structure of the measuring unit.

[0018] Figure 5 This is a diagram showing another example of the structure of the sound meter according to the relevant implementation method.

[0019] Figure 6 This is a graph showing the results of Experiment Example 1.

[0020] Figure 7 This is a graph showing the results of Experiment Example 2.

[0021] Figure 8 This is a graph showing the results of Experiment Example 3.

[0022] Figure 9 This is a diagram illustrating an example of the structure of the sound meter related to Modification 1.

[0023] Figure 10 This is a diagram illustrating an example of the structure of the sound meter related to Modification 2.

[0024] Figure 11 This is a diagram illustrating an example of the structure of the sound meter related to Modification 3.

[0025] Figure 12 This is a diagram illustrating an example of the structure of the sound meter related to Modification 4.

[0026] Figure 13 This is a diagram illustrating an example of the structure of the sound meter related to Modification 5.

[0027] Figure 14 This is the first example of a diagram showing the relationship between the ratio of the horizontal width to the vertical width of the frame when viewed from the direction of sound travel and the directivity of the sound meter.

[0028] Figure 15This is the second example of a diagram showing the relationship between the ratio of the horizontal width to the vertical width of the frame when viewed from the direction of sound travel and the directivity of the sound meter. Detailed Implementation

[0029] (This is a publicly disclosed understanding)

[0030] In recent years, techniques for detecting or predicting malfunctions in machines and other equipment have been developed to detect non-audible sounds that cannot be detected by the human ear. Non-audible sounds are ultrasonic waves, which are less affected by audible sounds, thus enabling the detection of equipment malfunctions earlier than audible sounds.

[0031] However, ultrasonic sounds above 100kHz cannot be detected by plate microphones, thus the application of optical microphones is anticipated. Optical microphones do not utilize the mechanical resonance of a plate in sound detection, therefore they can detect sounds in frequency bands above 100kHz. However, optical microphones have lower sound pressure sensitivity compared to plate microphones; for example, they sometimes cannot detect sounds above 80dB.

[0032] The following is for reference Figure 1 An example of a conventional optical microphone will be explained. Figure 1 This diagram illustrates an example of the structure of a conventional optical microphone. Figure 1 The optical microphone 1 shown has the same structure as the sound collection system described in Patent Document 1. Furthermore, in Figure 1 The diagram shows a schematic cross-sectional view of the frame 20 cut along the ZX plane. The optical microphone 1 includes, for example, a laser Doppler oscillometer 10, a frame 20 consisting of a pair of reflectors 21a and 21b and an angle-adjusting reflector 22, and a processing unit 30. The pair of reflectors 21a and 21b each have a reflecting surface 211a and 211b facing the predetermined space W through which sound passes (i.e., the predetermined space W within the sound field). The direction of sound passage is indicated by a hollow arrow, but it could also be the Y-axis direction. The laser Doppler oscillometer 10 measures the sound pressure in the predetermined space W by emitting a laser beam into the predetermined space W and reading the Doppler phenomenon caused by the interference between the reflected laser beam and a reference light, based on the phase variation of the laser beam due to changes in the refractive index of air. At this time, as... Figure 1 As shown, the laser is reflected multiple times (in other words, it is reflected in multiple ways) between a pair of mirrors 21a and 21b, and is reflected by the reflecting surface 221 of the angle-adjusting mirror 22, returning to the laser Doppler oscillometer 10.

[0033] To improve the sound pressure sensitivity of the optical microphone 1, it is considered effective to extend the optical path length of the laser in the sound field. However, in the optical microphone 1, if the specified space W is expanded to extend the optical path length, the laser is affected by both the positive and negative pressure of the sound wave, resulting in a decrease in sound pressure sensitivity. For example, in... Figure 1 In the optical microphone 1 shown, the specified space W can be expanded by increasing the distance between a pair of parallel reflectors 21a and 21b and by increasing the longitudinal or lateral dimensions of these reflectors 21a and 21b. However, if the specified space W is expanded, both positive and negative pressure of the sound waves are contained within the specified space W, which sometimes leads to a decrease in sound pressure sensitivity. Furthermore, for example, in the optical microphone 1, by reducing the incident angle of the laser, the laser can be subjected to multiple reflections, thereby extending the optical path length of the laser. However, the laser is prone to shining on the end of the reflector due to slight vibrations, which sometimes leads to a decrease in sound pressure sensitivity.

[0034] Therefore, the inventors of this application conducted specific research on the above-mentioned issues and discovered that the optical path length of the laser in the specified space W can be extended without expanding the specified space W. This led to the discovery that a sound meter (so-called an optical microphone) with improved sound pressure sensitivity can be obtained.

[0035] Therefore, according to this disclosure, it is possible to provide a sound meter with improved sound pressure sensitivity.

[0036] (Summary of this disclosure)

[0037] The summary of the technical solution disclosed herein is as follows.

[0038] A sound measuring device according to the present disclosure includes: a light source that emits laser light; a frame that surrounds a predetermined space through which the sound travels in a manner intersecting with the direction of sound travel and having at least one reflective surface facing the predetermined space; and a light-receiving portion that receives the laser light obtained by multiple reflections from the at least one reflective surface; wherein the at least one reflective surface is configured such that, when the predetermined space is viewed from the direction of sound travel, the laser light is intersected and reflected multiple times within the predetermined space.

[0039] Therefore, the sound meter can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0040] For example, in a sound meter of a technical solution of this disclosure, the aforementioned at least one reflecting surface is formed by at least one concave surface or a flat surface.

[0041] Therefore, the sound meter can easily adjust the optical path length of the laser within a specified space to the desired length. Furthermore, the sound meter can also adjust the size of the specified space and the optical path length of the laser based on the location where the sound meter is installed, the size of the location, or the characteristics of the sound being measured (e.g., frequency or sound pressure level).

[0042] For example, in a sound meter of a technical solution of this disclosure, at least one of the aforementioned reflective surfaces may be continuously formed.

[0043] Therefore, the sound meter can have a continuous and smooth reflective surface, thus allowing for a larger area to reflect the laser. Consequently, based on the sound meter, users can easily design the laser's optical path, reducing losses caused by laser leakage from the reflective surface.

[0044] For example, in a sound meter of a technical solution of this disclosure, the aforementioned at least one reflective surface may be multiple reflective surfaces, and within the aforementioned defined space, the orientations of the multiple reflective surfaces may differ.

[0045] Therefore, the sound meter can make the laser cross and reflect in multiple different directions within a specified space, thus easily extending the optical path length within the specified space.

[0046] For example, in a sound meter of one of the technical solutions of this disclosure, when viewed from the direction of sound travel, the shape of the frame is a polygon with three or more sides.

[0047] Therefore, the sound meter can appropriately set the size, shape, or laser path length of the specified space according to the location where the sound meter is set, the size of the location, or the characteristics of the sound of the object being measured, so that it can measure sound more appropriately.

[0048] For example, in a sound meter of a technical solution related to this disclosure, the shape of the polygon may be a triangle, a quadrilateral, a pentagon, or a hexagon.

[0049] Therefore, the sound meter can appropriately reflect the laser and measure the sound.

[0050] For example, in a sound meter of a technical solution of this disclosure, the frame portion is composed of at least one reflective element, which is a plurality of reflective elements, and the plurality of reflective elements are arranged at a distance from each other.

[0051] Therefore, the sound meter can easily adjust the setting angle of multiple reflecting components. Consequently, the sound meter can easily adjust the optical path length of the laser within a specified space.

[0052] For example, in a sound meter of a technical solution related to this disclosure, the frame portion is composed of at least one reflective component, and the at least one reflective component is a single reflective component.

[0053] Therefore, the sound meter can measure sound more easily. For example, the sound meter only needs to be equipped with a frame consisting of a single reflector, eliminating the need to adjust the relative positions of the reflectors as required when the frame consists of two or more reflectors.

[0054] For example, the sound meter of one of the technical solutions of this disclosure may also include a collimating lens, through which the light source directs the laser into the specified space.

[0055] Therefore, during the multiple reflections of the laser within a specified space, the laser beam diameter is unlikely to increase, making it less prone to leakage from the reflecting surface. Consequently, the sound meter can reduce laser loss, thus improving sound pressure sensitivity.

[0056] For example, the sound meter of one of the technical solutions of this disclosure may also include at least one angle adjustment reflective component that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0057] Therefore, the sound meter can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0058] For example, in a sound meter of one of the technical solutions of this disclosure, the aforementioned at least one angle adjustment reflective component is disposed independently from the aforementioned frame portion.

[0059] Therefore, the sound meter can finely adjust the angle of the laser and the optical path of the laser.

[0060] For example, in a sound meter of a technical solution of this disclosure, at least one angle adjustment reflective component is fixedly disposed in the frame portion.

[0061] Therefore, the sound meter can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0062] In addition, these inclusive or specific technical solutions can also be implemented by systems, methods, devices, integrated circuits, computer programs or computer-readable CD-ROMs and other recording media, or by any combination of systems, methods, devices, integrated circuits, computer programs and recording media.

[0063] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The numerical values, shapes, materials, constituent elements, arrangement and connection methods of constituent elements, steps, and order of steps shown in the following embodiments are examples and are not intended to limit the scope of the claims. Furthermore, constituent elements in the following embodiments that are not described in the independent claims representing the highest-level concept are described as arbitrary constituent elements. In addition, the figures are not necessarily strictly illustrated. In the figures, substantially identical structures are given the same reference numerals, and sometimes repeated descriptions are omitted or simplified.

[0064] Furthermore, in this disclosure, terms such as parallel and perpendicular that indicate the relationship between elements, and terms such as rectangle that indicate the shape of elements, and numerical values, do not only have a strict meaning, but also imply substantially equal ranges, for example, including differences of a few percentage points.

[0065] (Implementation Method)

[0066] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings.

[0067] [1. Structure]

[0068] First, the structure of the sound meter in the relevant implementation method will be described. Figure 2 This is a diagram illustrating an example of the structure of the sound meter 100 according to an embodiment. Figure 3 It is Figure 2 The frame portion 120 shown is viewed from an oblique angle in a perspective view.

[0069] like Figure 2 As shown, the sound meter 100 includes, for example, a measuring unit 110, a housing unit 120, and a processing unit 130. The structure will be described below.

[0070] [Frame 120]

[0071] The frame portion 120 is composed of at least one reflective element that surrounds a predetermined space through which the sound passes in an manner intersecting the direction of sound travel. Figure 2 and Figure 3 In the example, the sound meter 100 detects sound traveling in a defined space from the positive Y-axis toward the ZX plane. Enclosing the defined space in a manner intersecting the direction of sound travel does not necessarily mean completely enclosing the defined space; it also includes a configuration where a portion of the defined space is enclosed by at least one reflecting member. Furthermore, when a pair of reflecting members are arranged in parallel, a configuration where the space is sandwiched between the pair of reflecting members is also included.

[0072] In one embodiment, the frame portion 120 is composed of two reflective members 121a and 121b, which are arranged at a distance from each other. In this case, the frame portion 120 may have at least one gap between the two reflective members 121a and 121b. The at least one gap may be, for example, a gap for allowing the laser to enter a predetermined space (hereinafter also referred to as an entrance port) and a gap for adjusting the reflection angle of the laser and sending it back to the entrance port (hereinafter also referred to as an angle adjustment port). The frame portion 120 may also have an angle adjustment reflective member 122 inside the angle adjustment port or outside the angle adjustment port (negative side of the Z-axis). The angle adjustment reflective member 122 has a reflective surface 1221, which is arranged facing the predetermined space. The angle adjustment reflective member 122 may be rotatably mounted on a support shaft (not shown) fixed to the two reflective members 121a and 121b, or it may be supported by a piezoelectric element that can be flipped. Therefore, the angle adjustment reflector 122 can adjust the reflection angle of the laser relative to the reflector 1221, so that the laser can return to the measuring unit 110 with high precision.

[0073] When viewed from the direction of sound travel, the shape of the frame portion 120 can also be triangular, quadrilateral, pentagonal, hexagonal, circular, or elliptical. Here, the shape of the frame portion 120 is quadrilateral.

[0074] The size of the frame 120 can also be set appropriately according to the design. For example, the width (length in the X-axis direction) and height (length in the Z-axis direction) can be 130mm, and the depth (length in the Y-axis direction) can be 20mm.

[0075] The two reflective components 121a and 121b each have at least one reflective surface. For example, such as Figure 3 As shown, the two reflecting components 121a and 121b each have multiple reflecting surfaces 1211a and 1211b, which are arranged to face a predetermined space. More specifically, when the predetermined space is viewed from the direction of sound travel (i.e., the Y-axis direction), the two reflecting surfaces 1211a and 1211b are arranged to cause multiple reflections of the laser light within the predetermined space. For example, the multiple reflecting surfaces 1211a are planar and are formed continuously. Furthermore, within the predetermined space, the multiple reflecting surfaces 1211a each have a different orientation. The multiple reflecting surfaces 1211a can also have different shapes and areas. For example, the shape of the reflecting surface 1211a can be square, rectangular, or trapezoidal, and its area can also vary depending on the arrangement position of the reflecting surface 1211a of the reflecting component 121a (e.g., corners and ends). The same applies to the multiple reflecting surfaces 1211b.

[0076] Furthermore, regarding the plurality of reflecting surfaces 1211a of the reflecting component 121a, two adjacent consecutive reflecting surfaces 1211a form a concave portion and a convex portion with each other. In this case, the angle between two adjacent reflecting surfaces 1211a is preferably a right angle (tolerance: ±0.01). Furthermore, the plurality of reflecting surfaces 1211a are all planar. In this case, the surface accuracy of each reflecting surface 1211a is preferably 4λ or less. Furthermore, the reflectivity of each reflecting surface 1211a can be 90% or more in the wavelength of the laser used. The same applies to the plurality of reflecting surfaces 1211b.

[0077] In addition, multiple reflective surfaces 1211a may be formed continuously, but they may also not be formed continuously.

[0078] For example, when multiple reflective surfaces 1211a are formed continuously, a base (or substrate) can be formed from a substrate such as glass, metal, ceramic, or resin, and the reflective component 121a can be fabricated by forming a metal reflective film, an anti-reflective film, a dielectric single-layer film, a dielectric multilayer film, or a protective film on multiple surfaces that serve as multiple reflective surfaces 1211a. The base (or substrate) can also be formed, for example, by a known manufacturing method such as a frame. The metal reflective film is a film used to reflect laser light, and is formed, for example, from a metallic material such as silver or aluminum. The anti-reflective film can also be composed of a dielectric multilayer film, or it can be formed on the metal reflective film. A protective film is formed on the metal reflective film to physically or scientifically protect the metal reflective film. Alternatively, the reflective component 121a can also be fabricated by mirror finishing a metal such as aluminum, stainless steel, brass, iron, or titanium.

[0079] On the other hand, when the multiple reflective surfaces 1211a are not formed continuously, the reflective component 121a can also be manufactured by attaching reflective plates to multiple surfaces that are multiple reflective surfaces 1211a. The reflective plate can be, for example, a structure having a reflective surface with a reflectivity of 90% or more for the laser used, and is not particularly limited. For example, the reflective plate can also be a mirror with a thin film of highly reflective metal or dielectric such as aluminum, gold, or silver deposited on a glass substrate, or a metal plate with a mirror finish.

[0080] Furthermore, the multiple reflective surfaces 1211b are formed continuously, just like the multiple reflective surfaces 1211a, but they may not be formed continuously. In this case, the reflective member 121b is also manufactured in the same manner as the reflective member 121a.

[0081] [Measurement Department 110]

[0082] The measuring unit 110 emits a laser beam into a predetermined space and measures the sound pressure within that space based on the phase variation of the laser beam (hereinafter also referred to as reflected light) reflected back to the measuring unit 110 within the predetermined space surrounded by reflecting members 121a and 121b. The measuring unit 110 is, for example, a laser Doppler vibrator or a photodiode. When the measuring unit 110 is a laser Doppler vibrator, it has, for example, [features such as...]. Figure 4 The structure shown. Figure 4 It is used to explain Figure 2 A diagram showing an example of the structure of the measuring unit 110.

[0083] like Figure 4 As shown, the measurement unit 110 has a light source 111 that emits laser light. The laser light output from the light source is split into two directions by a first beam splitter 112a. One of the laser beams split into two directions, L1 (the so-called emitted light), is emitted through a second beam splitter 112b. On the other hand, the other laser beam, L2, split by the first beam splitter 112a, has its optical axis adjusted by a mirror 113 and is incident on an AOM 114b driven by an AOM (Acoustic-Optical Modulator) driver 114a. A reference light with the laser frequency shifted is output from the AOM 114b. The reference light is optically adjusted by a third beam splitter 112c to illuminate a light receiving unit 115 (e.g., a photodetector). Furthermore, the laser L3 reflected back in the designated space (the so-called reflected light) is irradiated onto the light-receiving unit 115 via the second beam splitter 112b and the third beam splitter 112c, and superimposed with the reference light to form interference light, which is received by the light-receiving unit 115. The measurement unit 110 uses the detection circuit 116 to detect the phase change of the laser generated by this superimposed interference and outputs it as an analog signal.

[0084] [Computation Department 130]

[0085] The arithmetic unit 130 calculates the sound pressure within a specified space based on the signal output from the measurement unit 110. For example, the arithmetic unit 130 may also be a frequency analysis device.

[0086] Furthermore, the example described for the measurement unit 110, which includes a light source 111 and a light receiving unit 115 within a single housing, is a laser Doppler oscillometer, but it is not limited to this. Alternatively, the measurement unit 110 may house the light source 111 and the light receiving unit 115 in separate housings. Moreover, the first beam splitter 112a, the second beam splitter 112b, the third beam splitter 112c, the AOM 114b, and the mirror 113 may not be included in a single housing, as is not limited to the light source 111 and the light receiving unit 115.

[0087] Alternatively, the light source 111 can be, for example, a He-Ne laser emitter or a laser diode.

[0088] [Collimating Lens 140]

[0089] The sound meter 100 may also include a collimating lens 140 (see reference). Figure 5 ). Figure 5 This is a diagram showing another example of the structure of the sound meter 100 according to the relevant implementation.

[0090] like Figure 5 As shown, light source 111 (reference) Figure 4 The laser beam is incident into a designated space via a collimating lens 140. This prevents a slight increase in the laser beam diameter during reflection within the designated space, thus reducing laser leakage from reflecting surfaces 1211a and 1211b. Consequently, the loss of reflected light received by the measuring unit 110 is reduced, thereby improving the sound pressure sensitivity of the sound meter 100.

[0091] [2. Experimental Example]

[0092] The following describes a simulation of the sound meter 100 according to the relevant embodiment and the results thereof.

[0093] [Experimental Example 1]

[0094] In Experiment 1, the effect of suppressing beam dilation caused by focal distance and different collimating lenses was simulated. The beam diameter was calculated based on the propagation theory of Gaussian beams. The results are expressed as follows: Figure 6 middle.

[0095] Figure 6 This is a graph representing the results of Experiment Example 1. In Figure 6 In the study, 13 collimating lenses with different focal distances were used to illustrate the relationship between the focal distance f (mm) of the collimating lens, the distance from the collimating lens (so-called optical path length) (m), and the beam diameter (mm) of the laser emitted through the collimating lens.

[0096] like Figure 6 As shown, the shorter the focal distance, the shorter the distance at which the laser can remain parallel. Simulation results show that if a collimating lens with a focal distance of 150mm is used, the expansion of the laser beam diameter is suppressed, and the laser remains parallel within a 5m optical path length from the lens.

[0097] The simulation results confirm that the laser light source 111, through the collimating lens 140, directs the laser into a designated space, and the laser remains parallel. Therefore, it is confirmed that the sound pressure meter 100, by also incorporating the collimating lens 140, further enhances its sound pressure sensitivity.

[0098] [Experimental Example 2]

[0099] Next, in Experiment 2, the sound pressure sensitivity of the sound meter was simulated when the sound wave was a plane wave. In Experiment 2, using... Figure 1 The conventional optical microphone 1 and Figure 2 The sound meter 100 shown.

[0100] In optical microphone 1, when the laser is directed through a pair of plane mirrors ( Figure 1 When the light is reflected 10 times between the reflectors 21a and 21b, the optical path length is 2m.

[0101] In the sound meter 100, when the laser is directed at a pair of concave and convex reflectors ( Figure 2 When multiple reflections occur between reflecting components 121a and 121b, the optical path length is 4m. The results are expressed as follows: Figure 7 middle.

[0102] Figure 7 This is a graph showing the results of Experiment Example 2. Figure 7 In this study, the sound pressure level is calculated as the relative sound pressure level (dB) when the sound pressure in a 1m optical path is set to 0dB.

[0103] like Figure 7 As shown, the relative sound pressure level of the sound measured by the optical microphone 1 is 6 dB. Furthermore, the relative sound pressure level of the sound measured by the sound meter 100 is 12 dB. Therefore, it is confirmed that the sound meter 100 of Embodiment 1 has improved sound pressure sensitivity compared to the optical microphone 1.

[0104] [Experiment Example 3]

[0105] Next, in Experiment 3, the sound pressure sensitivity of the sound meter when the sound wave is a spherical wave was simulated. Specifically, in Experiment 3, the distance from the sound source to the frame parts 20 and 120 (also called the receiving part) was set to 1m for simulation. Furthermore, in Experiment 3, points identical to those in Experiment 2 are omitted, and only the differences are described. The results are presented in... Figure 8 middle.

[0106] Figure 8 This is a graph showing the results of Experiment Example 3. In Figure 8 In this context, the sound pressure level is calculated as the relative sound pressure level (dB) when the 0Hz frequency of the sound meter 100 is set to 0dB. Furthermore, in... Figure 8 In the figure, the relative sound pressure level represents the effective value of the integral of the sound pressure along the optical path in the time direction at each frequency.

[0107] like Figure 8As shown, the relative sound pressure level measured by the sound meter 100 is higher than the relative sound pressure level measured by the optical microphone 1. The maximum relative sound pressure level difference is 7.93 dB (230 kHz). Therefore, it is confirmed that the sound meter 100 of Embodiment 1 has improved sound pressure sensitivity compared to the optical microphone 1.

[0108] [3. Effects, etc.]

[0109] As described above, the sound meter 100 of the embodiment includes: a light source 111 that emits laser light; a frame portion 120 that surrounds a predetermined space through which the sound travels in a manner intersecting with the direction of sound travel, and has at least one reflecting surface 1211a, 1211b facing the predetermined space; and a light receiving portion 115 that receives laser light obtained by multiple reflections from the at least one reflecting surface 1211a, 1211b; the at least one reflecting surface 1211a, 1211b is configured such that, when the predetermined space is viewed from the direction of sound travel, the laser light crosses and reflects multiple times within the predetermined space.

[0110] Therefore, the sound meter 100 can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0111] For example, in the sound meter 100 of the relevant embodiments, at least one reflective surface 1211a, 1211b may be formed by at least one concave surface or a flat surface.

[0112] Therefore, the sound meter 100 can easily adjust the optical path length of the laser within the specified space to the desired length. In addition, for example, the sound meter 100 can also adjust the size of the specified space and the optical path length of the laser according to the location where the sound meter 100 is set, the size of the location, or the characteristics of the sound of the object being measured (e.g., frequency or sound pressure level).

[0113] For example, in the sound meter 100 of the relevant embodiment, at least one reflective surface 1211a, 1211b may be formed continuously.

[0114] Therefore, the sound meter 100 can have a continuous and smooth reflective surface, thus enabling a larger area to reflect the laser. Consequently, based on the sound meter 100, the user can easily design the laser optical path and reduce losses caused by laser leakage from the reflective surface.

[0115] For example, in the sound meter 100 of the relevant implementation, at least one reflective surface 1211a, 1211b may be multiple reflective surfaces, and the multiple reflective surfaces may have different orientations within a specified space.

[0116] Therefore, the sound meter 100 can make the laser cross and reflect in multiple different directions within a specified space, so it can easily extend the optical path length within the specified space.

[0117] For example, in the sound meter 100 of the relevant embodiment, when viewed from the direction of sound travel, the shape of the frame portion 120 is a polygon with three or more sides.

[0118] Therefore, the sound meter 100 can appropriately set the size, shape, or laser path length of the specified space according to the location where the sound meter 100 is set, the size of the location, or the characteristics of the sound of the object being measured, so that it can measure sound more appropriately.

[0119] For example, in the sound meter 100 of the relevant implementation, the polygon shape may be triangular, quadrilateral, pentagonal or hexagonal.

[0120] Therefore, the sound meter can appropriately reflect the laser and measure the sound.

[0121] For example, in the sound meter 100 of the relevant embodiment, the frame portion 120 is composed of at least one reflective member 121a, 121b, and the at least one reflective member 121a, 121b is a plurality of reflective members, and the plurality of reflective members 121a, 121b are arranged at a distance from each other.

[0122] Therefore, the sound meter 100 can easily adjust the setting angle of the multiple reflecting components 121a, 121b. Consequently, the sound meter 100 can easily adjust the optical path length of the laser within a specified space.

[0123] For example, in the sound meter 100 of the relevant embodiment, the frame portion 120 is composed of at least one reflective member 121a, 121b, and the at least one reflective member 121a, 121b is a single reflective member.

[0124] Therefore, the sound meter 100 can measure sound more easily. For example, the sound meter only needs to be equipped with a frame consisting of a single reflective element, eliminating the need for adjusting the relative positions of the reflective elements as required for a frame consisting of two or more reflective elements.

[0125] For example, the sound meter 100 in the embodiment may also include a collimating lens, through which the light source directs the laser beam into a predetermined space.

[0126] Therefore, during the multiple reflections of the laser within a specified space, the beam diameter of the laser is not easily increased, and the laser is less likely to leak out from the reflecting surface. Consequently, the sound meter 100 can reduce laser loss and improve sound pressure sensitivity.

[0127] For example, the sound meter 100 of the embodiment may also include at least one angle adjustment reflective member 122 that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0128] Therefore, the sound meter 100 can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0129] For example, in the sound meter 100 of the relevant embodiment, at least one angle adjustment reflector 122 may be disposed independently from the frame portion 120.

[0130] Therefore, the sound meter 100 can finely adjust the angle of the laser and finely adjust the optical path of the laser.

[0131] For example, in a sound meter 100 of a technical solution of this disclosure, at least one angle adjustment reflective component 122 is fixedly disposed in the frame portion 120.

[0132] Therefore, the sound meter 100 can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0133] (Variation Example 1)

[0134] [1. Structure]

[0135] Next, the structure of the sound meter in Modification 1 will be described. Figure 9 This is a diagram illustrating an example of the structure of the sound meter 100a related to Modified Example 1.

[0136] The sound meter 100 described in the embodiment illustrates an example with two reflective components 121a and 121b having a concave-convex reflective surface with multiple planar reflective surfaces continuously formed. However, the sound meter 100a of Modified Example 1 differs from the embodiment in that it has four reflective components 221a, 221b, 221c, and 221d having a single planar reflective surface. Hereinafter, the differences from the embodiment will be explained.

[0137] The four reflective components 221a, 221b, 221c, and 221d each have a reflective surface 2211a, 2211b, 2211c, and 2211d, respectively. These reflective surfaces are planar and face the specified space.

[0138] Furthermore, in the sound meter 100a, the reflecting components 221a and 221c are arranged in parallel, and the reflecting components 221b and 221d are arranged in parallel.

[0139] Furthermore, the frame portion 120a includes two angle-adjusting reflective members 222a and 222b. The angle-adjusting reflective member 222a adjusts the reflection angle of the laser reflected by the reflective surface 2221a by adjusting the orientation of the reflective surface 2221a. That is, the angle-adjusting reflective member 222a is used to return the laser to the measuring unit 110. In addition, the angle-adjusting reflective member 222b uses the reflective surface 2221b to reflect the laser, which undergoes multiple reflections in the Z-axis direction between the pair of reflective members 221b and 221d, towards the reflective member 221a. Thus, the laser undergoes multiple reflections in the X-axis direction between the pair of reflective members 221a and 221c.

[0140] The sound meter 100a of Modified Example 1, by having the above-described structure, can cause multiple reflections of the laser in the longitudinal and transverse directions within a specified space, so the optical path length can be extended without changing the size of the sound receiving part.

[0141] Alternatively, the angle adjustment reflective components 222a and 222b may be configured independently of the reflective components 221a to 221d. For example, the angle adjustment reflective component 222a may be fixed to the reflective component 221b or the reflective component 221c. Furthermore, for example, the angle adjustment reflective component 222b may be fixed to the reflective component 221c or the reflective component 221d.

[0142] [2. Effects, etc.]

[0143] As described above, the sound meter 100a of the embodiment includes: a light source 111 (see reference 111). Figure 4 The laser beam is emitted; the frame 120a surrounds the space through which the sound travels in a manner intersecting the direction of sound travel, and has at least one reflective surface 2211a, 2211b, 2211c, 2211d facing the space; and the light-receiving part 115 (see reference) Figure 4 The laser is received by multiple reflections from at least one reflective surface 2211a, 2211b, 2211c, 2211d; the at least one reflective surface 2211a, 2211b, 2211c, 2211d is configured to cause the laser to cross and reflect multiple times in the specified space when viewed from the direction of sound travel.

[0144] Therefore, the sound meter 100a can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0145] For example, in the sound meter 100a of the relevant embodiments, at least one reflective surface 2211a, 2211b, 2211c, 2211d is formed by at least one concave surface or flat surface.

[0146] Therefore, the sound meter 100a can easily adjust the optical path length of the laser within the specified space to the desired length. In addition, for example, the sound meter 100a can also adjust the size of the specified space and the optical path length of the laser according to the location where the sound meter 100a is installed, the size of the installation location, or the characteristics of the sound of the object being measured (such as frequency or sound pressure).

[0147] For example, in the sound meter 100a of the relevant embodiment, at least one reflective surface 2211a, 2211b, 2211c, 2211d may be formed continuously.

[0148] Therefore, the sound meter 100a can have a continuous and smooth reflective surface, thus enabling a larger area to reflect the laser. Consequently, based on the sound meter 100a, users can easily design the laser optical path and reduce losses caused by laser leakage from the reflective surface.

[0149] For example, in the sound meter 100a of the relevant implementation, at least one reflective surface 2211a, 2211b, 2211c, 2211d is a plurality of reflective surfaces, and the plurality of reflective surfaces have different orientations within a specified space.

[0150] Therefore, the sound meter 100a can make the laser cross and reflect in multiple different directions within a specified space, so it can easily extend the optical path length within the specified space.

[0151] For example, in the sound meter 100a of the relevant embodiment, when viewed from the direction of sound travel, the shape of the frame portion 120a is a polygon with three or more sides.

[0152] Therefore, the sound meter 100a can appropriately set the size, shape, or laser path length of the specified space according to the location where the sound meter 100a is set, the size of the location, or the characteristics of the sound of the object being measured, so that it can measure sound more appropriately.

[0153] For example, in the sound meter 100a of the relevant embodiments, the polygon shape may be triangular, quadrilateral, pentagonal or hexagonal.

[0154] Therefore, the sound meter 100a can appropriately reflect the laser and appropriately measure the sound.

[0155] For example, in the sound meter 100a of the relevant embodiment, the frame portion 120 is composed of at least one reflective member 221a, 221b, 221c, 221d. The at least one reflective member 221a, 221b, 221c, 221d is a plurality of reflective members, and the plurality of reflective members 221a, 221b, 221c, 221d are arranged at a distance from each other.

[0156] Therefore, the sound meter 100a can easily adjust the setting angles of the multiple reflecting components 221a, 221b, 221c, and 221d. Consequently, the sound meter 100a can easily adjust the optical path length of the laser within a specified space.

[0157] For example, the sound meter 100a of the embodiment may also include at least one angle adjustment reflective component (222a, 222b) that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0158] Therefore, the sound meter 100a can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0159] For example, in the sound meter 100a of the relevant embodiment, at least one angle adjustment reflective member (222a, 222b) may be independently disposed from the frame portion 120a.

[0160] Therefore, the sound meter 100a can finely adjust the angle of the laser and finely adjust the optical path of the laser.

[0161] For example, in a sound meter 100a of a technical solution of this disclosure, at least one angle adjustment reflective component (222a, 222b) is fixedly disposed in the frame portion 120a.

[0162] Therefore, the sound meter 100a can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0163] (Variation Example 2)

[0164] [1. Structure]

[0165] Next, the structure of the sound meter in Modification Example 2 will be described. Figure 10 This is a diagram illustrating an example of the structure of the sound meter 100b related to Modification 2.

[0166] The sound meter 100a of Modification 1 illustrates an example with four reflective elements 221a, 221b, 221c, and 221d, each having a planar reflective surface. Reflective elements 221a and 221c are arranged in parallel. The sound meter 100b of Modification 2 differs from Modification 1 in that the four reflective elements 321a, 321b, 321c, and 321d, each having a planar reflective surface, are arranged in a triangular shape to enclose a predetermined space when viewed from the direction of sound propagation. The differences from the embodiment and Modification 1 will be explained below.

[0167] Four reflecting components 321a, 321b, 321c, and 321d each have a reflecting surface 3211a, 3211b, 3211c, and 3211d, respectively. These reflecting surfaces are planar and face a predetermined space. Furthermore, the frame portion 120b includes an angle-adjusting reflecting component 322. The angle-adjusting reflecting component 322 adjusts the reflection angle of the laser on the reflecting surface 3221 by adjusting the orientation of the reflecting surface 3221. That is, the angle-adjusting reflecting component 322 is used to return the laser to the measuring unit 110.

[0168] The sound meter 100b of Modified Example 2, having the above-described structure, can cause multiple reflections of the laser in three directions within a specified space, thus extending the optical path length without changing the size of the sound receiving part.

[0169] Alternatively, the angle adjustment reflector 322 may not be configured independently of the reflectors 321a and 321b. For example, the angle adjustment reflector 322 may be fixed to either the reflector 321a or the reflector 321b.

[0170] [2. Effects, etc.]

[0171] As described above, the sound meter 100b of the embodiment includes: a light source 111 (see reference 111). Figure 4 The laser beam is emitted; the frame portion 120b surrounds the space through which the sound travels in a manner intersecting the direction of sound travel, and has at least one reflecting surface 3211a, 3211b, 3211c, 3211d facing the space; and the light-receiving portion 115 (see reference) Figure 4 The laser is received by multiple reflections from at least one reflective surface 3211a, 3211b, 3211c, 3211d; the at least one reflective surface 3211a, 3211b, 3211c, 3211d is configured to cause the laser to cross and reflect multiple times in the specified space when viewed from the direction of sound travel.

[0172] Therefore, the sound meter 100b can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0173] For example, in the sound meter 100b of the relevant embodiment, at least one reflective surface 3211a, 3211b, 3211c, 3211d is formed by at least one concave surface or flat surface.

[0174] Therefore, the sound meter 100b can easily adjust the optical path length of the laser within the specified space to the desired length. In addition, for example, the sound meter 100b can also adjust the size of the specified space and the optical path length of the laser according to the location where the sound meter 100b is installed, the size of the installation location, or the characteristics of the sound of the object being measured (such as frequency or sound pressure).

[0175] For example, in the sound meter 100b of the relevant embodiment, at least one reflective surface 3211a, 3211b, 3211c, 3211d may be formed continuously.

[0176] Therefore, the sound meter 100b can have a continuous and smooth reflective surface, thus enabling a larger area to reflect the laser. Consequently, based on the sound meter 100b, users can easily design the laser's optical path and reduce losses caused by laser leakage from the reflective surface.

[0177] For example, in the sound meter 100b of the relevant implementation, at least one reflective surface 3211a, 3211b, 3211c, 3211d is a plurality of reflective surfaces, and within a specified space, the plurality of reflective surfaces 3211a, 3211b, 3211c, 3211d each have a different orientation.

[0178] Therefore, the sound meter 100b can make the laser cross and reflect in multiple different directions within a specified space, thus making it easy to extend the optical path length within the specified space.

[0179] For example, in the sound meter 100b of the relevant embodiment, when viewed from the direction of sound travel, the shape of the frame portion 120b is a polygon with three or more sides.

[0180] Therefore, the sound meter 100b can appropriately set the size, shape, or optical path length of the specified space according to the location where the sound meter 100b is installed, the size of the installation location, or the characteristics of the sound of the object being measured, so that it can measure sound more appropriately.

[0181] For example, in the sound meter 100b of the relevant embodiment, the frame portion 120b is composed of at least one reflective member 321a, 321b, 321c, 321d. The at least one reflective member 321a, 321b, 321c, 321d is a plurality of reflective members, and the plurality of reflective members 321a, 321b, 321c, 321d are arranged at a distance from each other.

[0182] Therefore, the sound meter 100b can easily adjust the setting angles of the multiple reflecting components 321a, 321b, 321c, and 321d. Consequently, the sound meter 100b can easily adjust the optical path length of the laser within a specified space.

[0183] For example, the sound meter 100b of the embodiment may also include at least one angle adjustment reflective member 322 that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0184] Therefore, the sound meter 100b can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0185] For example, in the sound meter 100b of the relevant embodiment, at least one angle adjustment reflector 322 may be independently disposed from the frame portion 120b.

[0186] Therefore, the sound meter 100b can finely adjust the angle of the laser and finely adjust the optical path of the laser.

[0187] For example, in a sound meter 100b of a technical solution of this disclosure, at least one angle adjustment reflective component 322 is fixedly disposed in the frame portion 120b.

[0188] Therefore, the sound meter 100b can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0189] (Variation Example 3)

[0190] [1. Structure]

[0191] Next, the structure of the sound meter in Modification Example 3 will be described. Figure 11 This is a diagram illustrating an example of the structure of the sound meter 100c related to Modified Example 3.

[0192] The sound meter 100b of Modification 2 shows an example of having four reflective members 321a, 321b, 321c, and 321d with planar reflective surfaces, wherein the reflective members 321a, 321b, 321c, and 321d are arranged in a triangular shape to enclose a predetermined space when viewed from the direction of sound travel. The sound meter 100c of Modification 3 differs from the Embodiment, Modification 1, and Modification 2 in that it has one reflective member 421 with a concave-convex reflective surface formed by multiple planar reflective surfaces continuously, and the frame portion 120c is hexagonal when viewed from the direction of sound travel. Hereinafter, the differences from the Embodiment, Modification 1, and Modification 2 will be explained.

[0193] The reflecting member 421 has multiple reflecting surfaces 4211. These reflecting surfaces are planar and continuously formed. Furthermore, the frame portion 120c includes an angle-adjusting reflecting member 422. The angle-adjusting reflecting member 422 adjusts the reflection angle of the laser on the reflecting surface 4221 by adjusting the orientation of the reflecting surface 4221. That is, the angle-adjusting reflecting member 4222 is used to return the laser to the measuring unit 110.

[0194] The sound meter 100c of Modified Example 3, by having the above-described structure, can cause the laser to be reflected multiple times in various directions within a specified space, so the optical path length can be extended without changing the size of the sound receiving part.

[0195] Alternatively, the angle adjustment reflector 422 may not be configured independently of the reflector 421. For example, the angle adjustment reflector 422 may be fixed to the reflector 421.

[0196] [2. Effects, etc.]

[0197] As described above, the sound meter 100c of the embodiment includes: a light source 111 (see reference 111). Figure 4 The laser beam is emitted; the frame portion 120c surrounds the space through which the sound travels in a manner intersecting the direction of sound travel, and has at least one reflective surface 4211 facing the space; and the light-receiving portion 115 (see reference) Figure 4 The laser is received by multiple reflections by at least one reflective surface 4211; the at least one reflective surface 4211 is configured to cause the laser to cross and reflect multiple times in the specified space when viewed from the direction of sound travel.

[0198] Therefore, the sound meter 100c can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0199] For example, in the sound meter 100c of the relevant embodiment, at least one reflective surface 4211 may be formed by at least one concave surface or a flat surface.

[0200] Therefore, the sound meter 100c can easily adjust the optical path length of the laser within the specified space to the desired length. Furthermore, for example, the sound meter 100c can also adjust the size of the specified space and the optical path length of the laser based on the location where the sound meter 100c is installed, the size of the installation location, or the characteristics of the sound being measured (e.g., frequency or sound pressure level).

[0201] For example, in the sound meter 100c of the relevant embodiment, at least one reflective surface 4211 may be continuously formed.

[0202] Therefore, the sound meter 100c can have a continuous and smooth reflective surface, thus enabling a larger area to reflect laser light. Consequently, based on the sound meter 100c, users can easily design the laser optical path and reduce losses caused by laser leakage from the reflective surface.

[0203] For example, in the sound meter 100c of the relevant implementation, at least one reflective surface 4211 may be multiple reflective surfaces, and within a defined space, the multiple reflective surfaces 4211 may each have a different orientation.

[0204] Therefore, the sound meter 100c can make the laser cross and reflect in multiple different directions within a specified space, thus making it easy to extend the optical path length within the specified space.

[0205] For example, in the sound meter 100c of the relevant embodiment, when viewed from the direction of sound travel, the shape of the frame portion 120c is a polygon with three or more sides.

[0206] Therefore, the sound meter 100c can appropriately set the size, shape, or optical path length of the specified space according to the location where the sound meter 100c is set, the size of the location, or the characteristics of the sound of the object being measured, so that it can measure sound more appropriately.

[0207] For example, in the sound meter 100c of the relevant embodiment, the frame portion 120c is composed of at least one reflective member 421, and the at least one reflective member 421 is a single reflective member.

[0208] Therefore, the sound meter 100c can measure sound more easily. For example, the sound meter 100c only needs to be provided with a frame 120c consisting of a single reflector 421, eliminating the need for adjusting the relative positions of the reflectors as required when using a frame consisting of two or more reflectors.

[0209] For example, the sound meter 100c of the embodiment may also include at least one angle adjustment reflective member 422 that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0210] Therefore, the sound meter 100c can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0211] For example, in the sound meter 100c of the relevant embodiment, at least one angle adjustment reflector 422 may be independently disposed from the frame portion 120c.

[0212] Therefore, the sound meter 100c can finely adjust the angle of the laser and finely adjust the optical path of the laser.

[0213] For example, in a sound meter 100c of a technical solution of this disclosure, at least one angle adjustment reflective component 422 is fixedly disposed in the frame portion 120c.

[0214] Therefore, the sound meter 100c can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0215] (Variation Example 4)

[0216] [1. Structure]

[0217] Next, the structure of the sound meter in Modification Example 4 will be described. Figure 12 This is a diagram illustrating an example of the structure of the sound meter 100d related to Modification 4. Figure 12 (a) is a stereoscopic view of the sound meter 100d viewed from an obliquely upward angle. Figure 12 (b) is to Figure 12 (a) is a cross-sectional view of the frame 120d of the sound meter 100d cut by the ZX plane.

[0218] In the above-described embodiments and variations 1 to 3, the frame portions 120 to 120c each have at least one planar reflective surface, while in variation 4, it differs from the embodiments and variations 1 to 3 in that it has a concave reflective surface.

[0219] Here, a concave surface includes a surface that curves downward and is recessed; for example, a surface that is concave in the shape of a bowl is also called a concave surface.

[0220] The two reflecting components 521a and 521b each have a reflecting surface 5211a and 5211b. Each of these reflecting surfaces is concave and faces a predetermined space. Furthermore, the frame portion 120d includes an angle-adjusting reflecting component 522. The angle-adjusting reflecting component 522 adjusts the reflection angle of the laser on the reflecting surface 5221 by adjusting the orientation of the reflecting surface 5221. That is, the angle-adjusting reflecting component 522 is used to return the laser to the measuring unit 110.

[0221] With the structure described above, the sound measuring device 100d of Modification Example 4 can cause multiple reflections of the laser not only on the ZX plane but also in the direction of sound propagation (here, the Y-axis) between a single reflecting member 521a and 521b within a specified space. Therefore, the optical path length can be extended in the depth direction within the specified space.

[0222] [2. Effects, etc.]

[0223] As described above, the sound meter 100d according to the embodiment includes: a light source 111 (see reference) Figure 4 The laser beam is emitted; the frame portion 120d surrounds the space through which the sound travels in a manner intersecting the direction of sound travel, and has at least one reflective surface 5211a, 5211b facing the space; and the light-receiving portion 115 (see reference) Figure 4 The laser is received by multiple reflections from at least one reflective surface 5211a, 5211b; the at least one reflective surface 5211a, 5211b is configured to cause the laser to cross and reflect multiple times in the specified space when viewed from the direction of sound travel.

[0224] Therefore, the sound meter 100d can extend the optical path length of the laser within a specified space, thus improving the sound pressure sensitivity.

[0225] For example, in the sound meter 100d of the relevant embodiment, at least one reflective surface 5211a, 5211b may be formed by at least one concave surface or a flat surface.

[0226] Therefore, the sound meter 100d can easily adjust the optical path length of the laser within the specified space to the desired length. Furthermore, for example, the sound meter 100d can also adjust the size of the specified space and the optical path length of the laser based on the location where the sound meter 100d is installed, the size of the installation location, or the characteristics of the sound being measured (e.g., frequency or sound pressure level).

[0227] For example, in the sound meter 100d of the relevant embodiment, at least one reflective surface 5211a, 5211b may be formed continuously.

[0228] Therefore, the sound meter 100d can have a continuous and smooth reflective surface, thus enabling a larger area to reflect laser light. Consequently, based on the sound meter 100d, users can easily design the laser optical path and reduce losses caused by laser leakage from the reflective surface.

[0229] For example, in the sound meter 100d of the relevant embodiment, the frame portion 120d is composed of at least one reflective member 521a, 521b, and the at least one reflective member 521a, 521b is a plurality of reflective members, and the plurality of reflective members 521a, 521b are arranged at a distance from each other.

[0230] Therefore, the sound meter 100d can easily adjust the setting angles of the multiple reflecting components 521a and 521b. Consequently, the sound meter 100d can easily adjust the optical path length of the laser within a specified space.

[0231] For example, the sound meter 100d of the embodiment may also include at least one angle adjustment reflective member 522 that reflects the laser and is capable of adjusting the reflection angle of the laser.

[0232] Therefore, the sound meter 100d can adjust the reflection angle of the laser and adjust the optical path of the laser.

[0233] For example, in the sound meter 100d of the relevant embodiment, at least one angle adjustment reflective member 522 may be independently disposed from the frame portion 120d.

[0234] Therefore, the sound meter 100d can finely adjust the angle of the laser and the optical path of the laser.

[0235] For example, in a sound meter 100d of a technical solution of this disclosure, at least one angle adjustment reflective component 522 is fixedly disposed in the frame portion 120d.

[0236] Therefore, the sound meter 100d can stabilize the laser angle without it wobbling. Furthermore, it simplifies the structure.

[0237] (Variation Example 5)

[0238] [1. Structure]

[0239] Next, the structure of the sound meter in Modification 5 will be described. Figure 13 This is a diagram illustrating an example of the structure of the sound meter 100e related to Modification 5.

[0240] In the above-described embodiments and variations 1 to 4, the laser light incident from the measuring unit 110 into the predetermined space is returned to the measuring unit 110. However, in variation 5, the laser light is directed towards the light detection unit 160 without returning to the measuring unit 110.

[0241] The sound meter 100e of Modification 5 includes a light source 111, a frame portion 120d, a condenser lens 150, and a light detection unit 160. The light detection unit 160 is, for example, a photodiode. In Modification 5, the frame portion 120d differs in that it has the frame portion 120a of the embodiment and the angle adjustment reflective member 122.

[0242] The sound meter 100e of Modification 5, by having the above-described structure, can extend the optical path length, thus improving the sound pressure sensitivity. Furthermore, since the sound meter 100e does not require the laser to return to the measuring unit as in the relevant embodiments and modifications 1-4, it can measure sound more conveniently.

[0243] (Other implementation methods)

[0244] The above description, based on the aforementioned embodiments and variations, describes one or more technical solutions of the present disclosure related to a sound meter. However, the present disclosure is not limited to these embodiments and variations. As long as it does not depart from the spirit of the present disclosure, various modifications to the embodiments that can be conceived by those skilled in the art, or forms constructed by combining the constituent elements of different embodiments, can also be included within the scope of one or more technical solutions of the present disclosure.

[0245] For example, the directivity of the sound meter can be adjusted by changing the ratio of the horizontal width to the vertical width of the frame portion when viewed from the direction of sound travel. This reduces noise in the sound meter, thus improving sound measurement accuracy.

[0246] Alternatively, for example, the horizontal and vertical directivity of the sound meter can be adjusted to be different by increasing at least one of the horizontal and vertical widths of the frame portion when viewed from the direction of sound travel. This allows the sound meter to freely adjust its directivity to match the sound of the object being measured, thus improving the accuracy of sound measurement.

[0247] The following is for reference Figure 14 and Figure 15 The relationship between the ratio of the horizontal width to the vertical width of the aforementioned frame and the directivity of the sound meter will be explained in detail.

[0248] [Example 1]

[0249] The first example illustrates that the ratio of the horizontal width to the vertical width of the frame is 1:1. Figure 14 This is the first example of a diagram showing the relationship between the ratio of the horizontal width to the vertical width of the frame when viewed from the direction of sound travel and the directivity of the sound meter. Figure 14 In China, use Figure 2 The sound meter 100 is shown, but the frame 120 is omitted from the illustration for ease of observation.

[0250] Figure 14 (a) represents the sound-receiving section when viewed from the direction of sound travel within the frame 120. Through multiple reflections of the laser within a defined space surrounded by the frame 120, the sound-receiving section receives sound passing through that defined space. The sound-receiving section can be viewed, for example, as a microphone array with many microphones arranged along the optical path of the multiple-reflected laser. Specifically, in Figure 14 In (a), the solid line represents the optical path of the laser with multiple reflections within a specified space when the frame 120 is viewed from the direction of sound travel.

[0251] In the first example, a frame portion 120 is provided at a distance of 1m from the sound source. When the frame portion 120 is viewed from the direction of sound travel, the center of the sound-receiving portion (more specifically, the sound-source side surface of the sound-receiving portion, in other words, the sound-receiving surface) and the sound source are aligned in a straight line. Hereinafter, the straight line passing through the center of the sound-receiving portion and the sound source will be referred to as the main axis.

[0252] Figure 14 (b) is a graph showing the directivity of the sound meter when the measured sound frequency is 1kHz. Figure 14 (c) is a graph showing the directivity of the sound meter when the measured sound frequency is 10kHz. Figure 14 (b) and Figure 14 In (c), the horizontal axis represents the angle (deg), and the vertical axis represents the difference between the sound pressure measured on the main axis (angle = 0°) and the sound measured at each angle in the receiving part (in other words, the relative level).

[0253] like Figure 14 (b) and Figure 14 As shown in (c), it is confirmed that a directivity symmetrical with respect to the main axis is formed in the receiving part.

[0254] [Example 2]

[0255] The second example illustrates an example where the ratio of the horizontal width to the vertical width of the frame is 2:1. Figure 15This is the second example of a diagram showing the relationship between the ratio of the horizontal width to the vertical width of the frame when viewed from the direction of sound travel and the directivity of the sound meter. Figure 15 In the middle, the diagram of the frame part is also omitted from the point of view of easy observation.

[0256] Figure 15 (a) indicates the receiving part when viewing the frame from the direction of sound travel. Since the receiving part has already been described above, it is omitted here. Figure 15 In (a), the solid line represents the optical path of the laser with multiple reflections within a specified space when the frame is viewed from the direction of sound travel.

[0257] In the second example, a frame was also installed at a distance of 1m from the sound source.

[0258] Figure 15 (b) is a graph showing the directivity of the sound meter when the measured sound frequency is 1kHz. Figure 15 (c) is a graph showing the directivity of the sound meter when the measured sound frequency is 10kHz. Figure 15 (b) and Figure 15 In (c), the horizontal axis represents the angle (deg), and the vertical axis represents the difference between the sound pressure measured on the main axis (angle = 0°) and the sound measured at each angle in the receiving part (in other words, the relative level).

[0259] like Figure 15 (b) and Figure 15 As shown in (c), it was confirmed that a directivity symmetrical with respect to the main axis is formed in the receiving section. Furthermore, it was confirmed that if the width of the receiving section in the horizontal direction is larger than the width in the vertical direction, the directivity of the sound measured in the horizontal direction is higher than that measured in the vertical direction of the receiving section.

[0260] As described above, the technical solutions illustrated in Examples 1 and 2 may also be included in the sound measuring device of one or more technical solutions relating to this disclosure.

[0261] Furthermore, the technical solution disclosed herein is not limited to such a sound meter, but can also be a sound measurement method using the characteristic structural parts included in the device as steps. Furthermore, the technical solution disclosed herein can also be a computer program that causes a computer to execute the characteristic steps included in the sound measurement method. Additionally, the technical solution disclosed herein can also be a computer-readable, non-transitory recording medium containing such a computer program.

[0262] Industrial applicability

[0263] According to this disclosure, since the mechanical vibration of the vibrating plate is not used, a wider range of sound bands can be measured, especially ultrasonic sound. Therefore, by measuring ultrasonic sound, it can also be used for the early detection or prediction of malfunctions of equipment, etc., and for inferring human behavior.

[0264] Label Explanation

[0265] 1. Optical microphone

[0266] 10. Laser Doppler Vibration Meter

[0267] Mirrors 21a and 21b

[0268] Reflective components 121a, 121b, 221a, 221b, 221c, 221d, 321a, 321b, 321c, 321d, 421, 521a, 521b

[0269] Frame sections 20, 120, 120a, 120b, 120c, and 120d

[0270] 211a, 211b, 221, 1211a, 1211b, 1221, 2211a, 2211b, 2211c, 2211d, 2221a, 2221b, 3211a, 3211b, 3211c, 3211d, 3221, 4211, 4221, 5211a, 5211b, 5221 Reflecting surfaces

[0271] 22 Angle Adjustment Mirror

[0272] 122, 222a, 222b, 322, 422, 522 Angle Adjustment Reflective Components 30, 130 Calculation Unit

[0273] 100, 100a, 100b, 100c, 100d, 100e sound meters

[0274] 110 Measurement Department

[0275] 111 Light Source

[0276] 112a First Beam Splitter

[0277] 112b second beam splitter

[0278] 112c third beam splitter

[0279] 113 mirrors

[0280] 114a AOM driver

[0281] 114b AOM

[0282] 115 Light-receiving section

[0283] 116 Detection Circuit

[0284] 140 collimating lens

[0285] 150 Condensing Lens

[0286] 160 Optical Detection Department

Claims

1. A sound meter, wherein, have: Light source, emitting laser light; The frame surrounds the space through which the sound passes in a manner that intersects with the direction of sound travel, and has multiple reflective surfaces facing the space. as well as The light-receiving part receives the laser light obtained by multiple reflections from the aforementioned multiple reflective surfaces. The aforementioned multiple reflective surfaces are configured to cause the laser to cross and reflect multiple times within the specified space when viewed from the direction of sound travel. When the specified space is viewed from the direction of sound travel, the plurality of reflective surfaces are formed in a row of concave-convex reflective surfaces arranged alternately with concave portions on the side of the specified space and convex portions on the side of the specified space.

2. The sound meter as claimed in claim 1, wherein, The aforementioned multiple reflective surfaces are formed by at least one concave surface or a flat surface.

3. The sound meter as described in claim 2, wherein, The aforementioned multiple reflective surfaces are formed continuously.

4. The sound meter as described in any one of claims 1 to 3, wherein, Within the aforementioned defined space, the orientations of the multiple reflective surfaces are different.

5. The sound measuring device as described in any one of claims 1 to 3, wherein, When the frame is viewed from the direction of the sound's travel, the frame is a polygon with three or more sides.

6. The sound meter as described in claim 5, wherein, The shape of the aforementioned polygon can be triangular, quadrilateral, pentagonal, or hexagonal.

7. The sound meter as described in any one of claims 1 to 3, wherein, The aforementioned frame is composed of at least one reflective component; The aforementioned at least one reflective component can be multiple reflective components; The aforementioned reflective components are arranged at intervals.

8. The sound measuring device as described in any one of claims 1 to 3, wherein, The aforementioned frame is composed of at least one reflective component; At least one of the above-mentioned reflective components is a single reflective component.

9. The sound measuring device as described in any one of claims 1 to 3, wherein, The aforementioned sound meter also features a collimating lens; The aforementioned light source, through the aforementioned collimating lens, directs the aforementioned laser into the aforementioned designated space.

10. The sound measuring device according to any one of claims 1 to 3, wherein, The aforementioned sound meter also includes at least one angle-adjusting reflective component that reflects the aforementioned laser and is capable of adjusting the reflection angle of the aforementioned laser.

11. The sound meter as claimed in claim 10, wherein, The aforementioned at least one angle adjustment reflective component is independently configured from the aforementioned frame portion.

12. The sound meter as claimed in claim 10, wherein, At least one of the aforementioned angle-adjusting reflective components is fixedly disposed on the aforementioned frame portion.

13. The sound measuring device according to any one of claims 1 to 3, wherein, For the aforementioned frame portion, the directivity of the sound meter is adjusted by changing the ratio of the horizontal width to the vertical width of the frame portion when viewed from the direction of sound travel.

14. The sound measuring device according to any one of claims 1 to 3, wherein, For the aforementioned frame portion, by increasing at least one of the horizontal width and vertical width of the frame portion when viewed from the direction of sound travel, the directivity of the sound meter in the horizontal and vertical directions is adjusted to be different.

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