Sound transmission improvement structure

Abstract

To provide a structure that improves sound transmission performance of a partition member having a sound insulating property.SOLUTION: A splash prevention partition is fixed by inserting or placing a plate-like transparent partition member 1 from above into bifurcate parts of a support block 4. Transparent perforated plates 2 forming a resonance mechanism are fastened on both sides of the transparent partition member 1. A fastening method includes permanent magnets 5 being inserted into recesses formed at four corners of the transparent perforated plates 2, where permanent magnets 5 of the opposing transparent perforated plates 2 have reversed polarities. Therefore, by bringing the two transparent perforated plates 2 closer to each other while holding the transparent partition member 1 between them, the transparent perforated plates 2 are made to be mutually attracted and fixed.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a structure for improving the sound transmissibility applied to a sound-insulating partition member such as a splash-proof partition installed at places where people talk directly to each other, such as hospital windows, bank teller windows, and store cash registers, in order to prevent the spread of infectious diseases such as COVID-19.

Background Art

[0002] Patent Document 1 discloses a splash-proof partition in which a pair of legs are fixed to a base plate, a transparent panel is inserted into a slit of the leg from above, and the transparent panel is fixed to the leg with screws.

[0003] Patent Document 2 discloses a screen-type partition composed of a panel plate and a support column. This screen-type partition has one or more screw holes opened in the plate thickness direction of the panel plate, one or more guide grooves extending in the axial direction of the support column, one or more nut members that are guided by the guide grooves and are movable in the axial direction, and screws that are screwed into the nut members through the screw holes.

[0004] Even when a transparent plate or a thin vinyl sheet is used as a partition plate, relatively large sound attenuation occurs in the mid- and high-frequency ranges, resulting in the problem that conversations become difficult to hear. Therefore, in Non-Patent Document 1, the inventors of the present invention proposed a splash-proof partition plate provided with a resonance mechanism. The structure of this splash-proof partition plate utilizes resonance transmission by installing a perforated plate on the front surface of a transparent plate (single-layer plate) through an air layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0006] [Non-Patent Document 1] "Control of Transmitted Sound in Single-Layer Plates with Added Resonance Mechanism," Proceedings of the Research Conference of the Japan Society of Noise Control Engineering, Satoshi Sugie, Hajime Suzuki, Ryoma Nitta, November 2020. [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] While splash-proof partitions made of a single sheet of material such as acrylic, as disclosed in Patent Document 1 or 2, can prevent the spread of droplets, they suffer from significant sound reduction in the mid-to-high frequency range.

[0008] As disclosed in Non-Patent Document 1, by installing a perforated plate in front of a transparent plate (single-layer plate) with an air layer in between, it was possible to reduce sound attenuation in the mid-to-high frequency range, but the sound transmission performance is still not sufficient.

[0009] Furthermore, since Non-Patent Document 1 shows a high degree of dependence of the resonance frequency on the transparent plate, it is necessary to consider the optimal conditions for the transparent plate used to improve sound transmission performance. [Means for solving the problem]

[0010] To solve the above problems, the sound transmission improvement structure according to the present invention forms a resonance mechanism on both sides of a partition member that improves sound transmission performance by installing perforated plates on both sides of a sound-insulating partition member with an air layer in between.

[0011] Examples of the partition members include splash-proof partitions. Furthermore, as a means of attaching the perforated plate to the partition members, it is conceivable to secure the partition members to each other by using magnetic attraction. [Effects of the Invention]

[0012] According to the present invention, the sound transmission performance of conventional sound-insulating partition members such as transparent plates and vinyl sheets can be improved.

[0013] In particular, compared with the configuration in which the perforated plate is disposed only on one side of the partition member shown in Non-Patent Document 1, the transmission performance to the other side across the partition member can be improved.

[0014] Furthermore, by forming resonance mechanisms on both sides of the partition member, the degree to which the resonance frequency depends on the partition member is reduced, simplifying the design.

[0015] Also, by adopting a configuration in which the perforated plates on both sides are fixed with a partition member sandwiched therebetween using permanent magnets, the position of the perforated plate can be easily adjusted according to the physique of the user or the like.

Brief Description of the Drawings

[0016] [Figure 1] (a) is a front view of the apparatus used for the design of the additional resonator, and (b) is a cross-sectional view [Figure 2] Graph showing the estimated results of the normal incidence acoustic loss [Figure 3] Graph showing the measurement results of the intensity acoustic transmission loss [Figure 4] Layout diagram of the simulation counter [Figure 5] Graph showing the measurement results of the sound pressure level difference [Figure 6] Perspective view of the commercialized droplet prevention partition

Best Mode for Carrying Out the Invention

[0017] As shown in FIG. 1, perforated plates 2 are disposed on the left and right of a plate-shaped partition member 1 via an air layer 3 to form an additional resonator (resonance mechanism). The perforated plates defined the distance from the partition member 1 using a frame.

[0018] Assume that the structure of the device used in the design of the additional resonator is infinitely wide, and calculate the acoustic transmission loss under the condition of normal incidence of plane waves using the transfer matrix method. In this structure, two resonance frequencies (frp1, frp2) appear. Fix the lower frp1 at 1000 Hz, and estimate by changing the aperture ratio φ and the air layer thickness l. The estimation results of the normal incidence acoustic transmission loss R0 are shown in Fig. 2. The acoustic impedance Zph of the perforated plate was calculated using the following formula (1).

[0019]

Number

[0020] According to Fig. 2, under the conditions where l and φ are small, the dips at the two resonance frequencies are separated. However, as they increase, the dip of frp2 that appears at the higher frequency approaches frp1 and becomes like one dip.

[0021] It is considered that the wider the frequency range of the dip around frp1, the greater the decrease in the actual measurement results. Therefore, it is considered that l = 20 mm (φ = 3.7%) can effectively reduce the sound insulation performance.

[0022] To verify this estimation result, the measurement results of the intensity acoustic transmission loss R1 using a 500 mm square small test piece are shown in Fig. 3. However, each parameter is changed with frp1 being approximately 900 Hz. Although this result is under the condition of random incidence, it can be seen that l = 20 mm is the lowest in the actual measurement results.

[0023] Next, the simulation experiment will be described. A counter simulating a shop reception area, as shown in Figure 4, was installed in the opening (W3650 x H2740) of a Type II test chamber for acoustic transmission loss testing. A partition sheet (0.3 mm thick flexible polyvinyl chloride sheet) was suspended from the top of the opening. However, both the counter and the sheet were installed across the entire width of the opening. A 250 mm gap was provided between the sheet and the counter. Sound-absorbing material was also installed in the test chamber to adjust the reverberation time to approximately 0.5 seconds.

[0024] A directional speaker was installed at a point 600 mm away from the partition sheet (at a height of 1600 mm), and five omnidirectional microphones were uniformly distributed within the opposite plane, in an area that did not deviate from the front of the additional resonator. However, one of the microphones was positioned directly in front of the speaker.

[0025] Two additional resonators (500mm square) were installed with a vinyl sheet in between, so that their centers were positioned on the speaker's axis. The additional resonators were made from 0.4mm thick flexible polyvinyl chloride sheets with perforations of d=10mm and φ=2.6%. A 1mm thick magnetic sheet was attached to the frame for mounting, resulting in an air gap thickness l of 21mm. The calculated values ​​for frp1 and frp2 are 883Hz and 1288Hz, respectively.

[0026] Figure 5 shows the measurement results of the sound pressure level difference D obtained by subtracting the condition without the partition sheet from the condition with the partition sheet and the condition with an additional resonator attached to the partition sheet (a larger negative value indicates a greater shielding effect). However, noise was generated as the sound source, and the results are based on a time average over 20 seconds and a spatial average at 5 points.

[0027] As can be seen in Figure 5, by using a partition sheet, the sound pressure level on the opposite side hardly changes below 315 Hz, but a decrease of about 2 dB is observed at 500 Hz, and it gradually decreases as the frequency increases further. On the other hand, when an additional resonator is installed, the sound pressure level difference D approaches 0 dB near the resonant transmission frequency, and the sound pressure level rises to about the same level as under conditions without a partition sheet.

[0028] Furthermore, we investigated the optimal aperture ratio and air layer thickness to effectively improve permeability by installing additional resonators (resonance mechanisms) using perforated plates on both sides of lightweight, flexible sheets (0.3-0.4 mm thick) commonly used to prevent droplet infection. The results showed that transmission performance improved significantly near the resonance frequency when the aperture ratio was approximately 3% and the air layer thickness was approximately 20 mm.

[0029] Figure 6 shows a splash-proof partition that was commercialized by changing the partition sheet from a vinyl sheet to a thicker and heavier acrylic transparent sheet. The splash-proof partition is secured by either inserting a plate-shaped transparent partition member 1 from above into the bifurcated portion of the support block 4, or by covering the outside of the bifurcated portion with a bag formed at the lower end of the support block 4.

[0030] Transparent perforated plates 2, which form a resonance mechanism, are fixed to both sides of the transparent partition member 1. The fixing method involves fitting permanent magnets 5 into recesses formed in the four corners of the transparent perforated plates 2, and the permanent magnets 5 on opposing transparent perforated plates 2 are arranged so that their polarities are opposite. Therefore, by bringing the two transparent perforated plates 2 closer together with the transparent partition member 1 in between, the transparent perforated plates 2 are attracted to and fixed to each other.

[0031] Furthermore, a ring is attached to the back of the permanent magnet 5, allowing you to easily remove the transparent perforated plate 2 from the transparent partition plate 1. The position of the transparent perforated plate 2 can also be adjusted to suit the sitting height of the person having the conversation. Alternatively, the magnets could be attached to the end grain of the frame material, or to the edge (or part of the edge) of the transparent effective plate.

[0032] In this example, the diameter of the holes formed in the transparent perforated plate 2 was set to 10 mm, and the height of the edge of the transparent perforated plate 2, which determines the thickness of the air layer, was set to 11 mm. However, the diameter of the holes, the shape of the holes, and the height of the edge of the transparent perforated plate are not limited to these values.

[0033] While a splash-proof partition was shown as an example of a commercialized product, the sound transmission-enhancing structure according to the present invention can be applied to other uses as well. For example, it can be applied to transparent partitions between the driver's seat and the passenger seat of a taxi to enhance security, partitions between customers at ticket counters and currency exchange offices, as well as front doors and glass windows of houses, face shields, windows of microwave ovens, and entrances and walls of greenhouses. [Explanation of Symbols]

[0034] 1... Partition member, 2... Perforated plate, 3... Air layer, 4... Support block, 5... Permanent magnet.

Claims

1. A sound transmission improvement structure characterized by having perforated plates installed on both sides of a sound-insulating partition member via frames, and forming an air layer between the sides of the partition member and the perforated plates, thereby forming a resonance mechanism on both sides of the partition member that improves sound transmission performance.

2. The sound transmission improvement structure according to claim 1, characterized in that the partition member is a splash-proof partition.

3. The sound transmission improvement structure according to claim 1 or claim 2, characterized in that the perforated plates on both sides are equipped with magnets and are fixed to each other by the magnetic attraction force, sandwiching a partition member between them.

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