Acoustic facilities and methods for arranging acoustic facilities

Abstract

Reduces vibrations in specific surrounding areas. [Solution] In the acoustic facility 10, the stage 4 and the floor 1 are arranged such that a specific area 6 where vibration reduction is to be desired is located behind the stage 4 along the extension line 7 connecting the stage 4 and the floor 1.

Description

[Technical Field]

[0001] This disclosure relates to acoustic facilities that take vibration reduction into consideration, and to methods for arranging acoustic facilities. [Background technology]

[0002] Patent Document 1 discloses a vibration isolation structure comprising a concrete floor slab positioned in isolation from the surrounding structural frame, and support members arranged in a grid pattern in plan view, driven down to the supporting ground, and supporting the concrete floor slab in a non-contact state with the surface ground.

[0003] Patent Document 2 discloses a vibration control system for a facility having a housing means capable of housing a crowd in a single spatial area and an area of ​​interest to the crowd, which controls vibrations generated by the synchronized movements of the crowd housed in the housing means, comprising N (N≧3) motion timing transmission means for transmitting the timing of synchronized movements to the crowd, and a delay processing means for delaying the operation of the motion timing transmission means, wherein the motion timing transmission means are divided into M (N≧M≧3) groups, and the delay processing means delays the operation of the motion timing transmission means for each group.

[0004] Patent Document 3 discloses a vibration isolation method for structural floors, in which the floor of a structure is composed of a combination of vibration-isolated areas that are supported to prevent vibration from excitation and non-vibration-isolated areas that are not supported to prevent vibration. The method delays the phase of vibrations transmitted from the vibration-isolated areas to the substructure and cancels out the vibrations by utilizing the phase difference between these vibrations and vibrations transmitted from the non-vibration-isolated areas to the substructure. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-93762 [Patent Document 2] Japanese Patent Publication No. 2015-197012 [Patent Document 3] Japanese Patent Publication No. 2004-251064 [Overview of the project] [Problems that the invention aims to solve]

[0006] For example, hospitals or schools may be located near the planned construction site of an acoustic facility. In areas where hospitals or schools are located, it is preferable to reduce the vibrations transmitted from the acoustic facility as much as possible compared to other surrounding areas.

[0007] However, conventional vibration control methods assume that the vibration-generating floor is isolated from the ground and that the floor accommodating the audience is divided into multiple areas. Therefore, conventional vibration control methods cannot be used in acoustic facilities that, for various reasons, cannot adopt a structure that satisfies the prerequisites of these methods.

[0008] Furthermore, conventional vibration control methods focus on reducing vibrations generated in acoustic facilities, and do not focus on reducing vibrations in a targeted area.

[0009] This disclosure is made in view of the above facts and aims to provide an acoustic facility and a method for arranging an acoustic facility that can reduce vibrations in a specific surrounding area. [Means for solving the problem]

[0010] To achieve the above objective, the acoustic facility of this disclosure arranges the stage and the floor, respectively, such that a specific area where vibration reduction is to be desired is located behind the stage, along the extension of the line connecting the stage where performers perform and the floor where the audience is seated. In this way, the acoustic facility of this disclosure makes it possible to reduce vibration in a specific surrounding area.

[0011] Further, in the acoustic facility of the present disclosure, the floor is arranged such that a first length of the floor in the extension line direction is longer than a second length of the floor in a cross direction intersecting the extension line direction. As described above, according to the acoustic facility of the present disclosure, the vibration frequency in a specific region can be reduced as compared with a case where the floor has a square shape.

[0012] Further, in the acoustic facility of the present disclosure, the first length of the floor is not more than 1.5 times the second length of the floor. As described above, according to the acoustic facility of the present disclosure, the vibration frequency in a specific region can be reduced as compared with a case where the first length of the floor is more than 1.5 times the second length of the floor.

[0013] Further, the arrangement method for an acoustic facility according to the present disclosure is a method of arranging the stage and the floor respectively such that a specific region where vibration is to be reduced is located behind the stage along an extension line connecting the stage on which a performer performs and the floor accommodating an audience. As described above, according to the arrangement method for an acoustic facility of the present disclosure, vibration in a surrounding specific region can be reduced.

Effects of the Invention

[0014] According to the present disclosure, there is an effect that vibration in a surrounding specific region can be reduced.

Brief Description of Drawings

[0015] [Figure 1] It is a diagram showing an example of the minimum reduced vibration frequency and wavelength according to the number of excitation points and the interval between excitation points. [Figure 2] It is a diagram showing an example of a situation where the stage and the floor of the acoustic facility are viewed along the width direction of the floor. [Figure 3] It is a diagram showing an arrangement example of the stage, the floor, and the specific region. [Figure 4] It is a diagram showing a configuration example of the floor in Case 1. [Figure 5]This figure shows an example of the vertical acceleration of the ground surface at specified distances from an acoustic facility along the vibration propagation direction in Case 1. [Figure 6] This diagram shows an example of the floor layout in Case Study 2. [Figure 7] This figure shows an example of the vertical acceleration of the ground surface at specified distances from an acoustic facility along the vibration propagation direction in Case 2. [Figure 8] This figure shows an example of the vibration reduction range. [Figure 9] This figure shows examples of measurement points for vertical acceleration at the ground surface within the vibration reduction range. [Figure 10] This figure shows an example of the vertical acceleration of the ground surface at each measurement point within the vibration reduction range. [Figure 11] This figure shows an example of the vertical acceleration of the ground surface at each measurement point within the vibration reduction range. [Modes for carrying out the invention]

[0016] This embodiment will be described below with reference to the drawings. The same reference numerals are used throughout the drawings for the same components and processes, and redundant explanations are omitted. The dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from actual ratios.

[0017] Before describing this embodiment, two fundamental technical elements of this embodiment will be explained.

[0018] The first technical element concerns the frequency and wavelength of vibrations generated from Floor 1 (see Figure 3), where the audience is seated. On Floor 1 of the acoustic facility 10, the audience's mood is heightened by the performers' music, and they may move their bodies in time with the sound. These movements of the audience excite Floor 1, and the vibrations propagate from Floor 1 through the surface ground 2A (see Figure 1) to areas outside the site of the acoustic facility 10. Hereafter, the area outside the site of the acoustic facility 10 where vibrations from the acoustic facility 10 propagate will be referred to as the "surrounding area." Furthermore, vibrations on Floor 1, which is an example of an excited floor, are often generated by audience members swaying their bodies vertically while standing, and are therefore sometimes referred to as vibrations caused by "vertical swaying." Note that performers include not only instrumentalists but also vocalists. Performance by vocalists refers to the vocalists singing.

[0019] When the audience simultaneously stimulates Floor 1 by vertical movement, the location of the excitation force input to the surface ground 2A via Floor 1 differs depending on the position of each audience member. As a result, a phase difference occurs in the waves generated at each excitation force input point in the surface ground 2A. When a phase difference occurs in the waves, they interfere with each other and cancel out the vibrations, reducing the vibrations that propagate to the ground outside Floor 1.

[0020] Here, the frequency of the vibration to be reduced (hereinafter referred to as the "reduction frequency") is f [Hz], the number of excitation points is n, the interval between excitation points is d [m], and the vibration propagation velocity in the surface ground 2A is V. s If we consider the frequency to be [m / s], then the reduction frequency is f[Hz] that satisfies equation (1).

[0021]

number

[0022] The number of excitation points n refers to the number of locations on Floor 1 where vibrations are being applied due to the audience's vertical movement, i.e., the number of excitation points. The excitation point interval d is the distance between each excitation point. The unit of the excitation point interval d is [m].

[0023] Among the reduced frequencies f, the lowest reduced frequency f is denoted as the "minimum reduced frequency f1". Furthermore, among the wavelengths λ of reduced frequencies f, the wavelength of the minimum reduced frequency f1 is denoted as λ1. The unit of each wavelength λ, including wavelength λ1, is [m].

[0024] In this case, the wavelength λ1 at the minimum reduced frequency f1 is expressed by equation (2).

[0025]

number

[0026] Furthermore, the minimum reduced frequency f1 is expressed by equation (3).

[0027]

number

[0028] Figure 1 shows an example of the minimum reduction frequency f1 and wavelength λ1 depending on the number of excitation points n and the excitation point interval d.

[0029] As an example, vibration propagation velocity V s Assuming a stress of 50 [m / s], as shown in Figure 1(A), when the excitation point spacing d is 10 [m] and the number of excitation points n is 2, i.e., in the case of 2-point excitation, the minimum reduced frequency f1 is 2.5 [Hz]. Also, as shown in Figure 1(B), when the excitation point spacing d is 5 [m] and the number of excitation points n is 3, i.e., in the case of 3-point excitation, the minimum reduced frequency f1 is 3.3 [Hz]. Furthermore, as shown in Figure 1(C), when the excitation point spacing d is 2 [m] and the number of excitation points n is 6, i.e., in the case of 6-point excitation, the minimum reduced frequency f1 is 4.17 [Hz]. Note that in Figure 1, arrow 3 represents the position of the excitation point.

[0030] Furthermore, as the number of excitation points n increases, since the size of floor 1 is fixed, the interval d between excitation points shortens as the number of excitation points n increases. Therefore, the system transitions from a discrete multi-point excitation state to a linear excitation state. Under the conditions of Figure 1, as the number of excitation points n increases, the minimum reduction frequency f1 eventually becomes 5 [Hz], and the wavelength λ1 becomes the length between the excitation points at both ends in linear excitation, i.e., 10 [m] in the above example. The linear excitation state on floor 1 corresponds to a situation where there are no piles supporting floor 1, the underside of floor 1 is in contact with the surface ground 2A, and spectators who are present without gaps on floor 1, i.e., spectators positioned according to a uniform distribution, are all simultaneously performing vertical movements. Hereafter, the piles supporting floor 1 may be referred to as "supporting members 9".

[0031] In Figure 1, the surface ground 2A and the supporting ground 2B are combined and referred to as "Ground 2".

[0032] The second technical element concerns the arrival time of sound emitted from the stage where performers perform. Figure 2 shows an example of the view of the stage 4 and floor 1 of the sound facility 10 along the width direction of floor 1. The width direction of floor 1 refers to the direction along the side of floor 1 that is opposite to stage 4 among the sides that represent the extent of floor 1. In other words, the width direction of floor 1 is the direction perpendicular to the direction in which the audience on floor 1 views stage 4. On the other hand, the direction perpendicular to the width direction of floor 1 is referred to as the depth direction of floor 1. In other words, the depth direction of floor 1 refers to the direction along the side of floor 1 that represents the extent of floor 1, along the direction in which the audience on floor 1 views stage 4. Furthermore, the length of the side of floor 1 along the width direction is referred to as the width of floor 1, and the length of the side of floor 1 along the depth direction is referred to as the depth of floor 1. The depth of floor 1 is an example of the first length of floor 1 in this disclosure, and the width of floor 1 is an example of the second length of floor 1 in this disclosure.

[0033] Of the edges representing the extent of Stage 4, the direction along the edge of Stage 4 that is opposite Floor 1 is referred to as the width direction of Stage 4. On the other hand, the direction perpendicular to the width direction of Stage 4 is referred to as the depth direction of Stage 4. The width direction of Floor 1 and the width direction of Stage 4, as well as the depth direction of Floor 1 and the depth direction of Stage 4, represent the same direction.

[0034] For the sake of explanation, in Figure 2, arrow 5 is shown along the depth direction of Floor 1, indicating the position of Floor 1.

[0035] If a sound source (e.g., a speaker) is located on Stage 4, the arrival time of sound at other floor positions will be delayed compared to the area of ​​Floor 1 closer to Stage 4, i.e., the front row floor position represented by arrow 5A. The phase difference of sound from the front row floor position can be calculated using the relative distance between the front row floor position and each floor position, and the speed of sound (approximately 340 [m / s]). In Figure 2, if we consider the interval between each floor position as the excitation point interval and denote each floor position as "m", then the phase difference of sound at each floor position represented by arrows 5A to 5F is -2πmd / 340 [rad]. The "m" representing the floor position takes integer values ​​from 0 to 5 in order from the front row floor position, moving away from Stage 4.

[0036] Vibrations excited by sound excitation with a time difference along the depth direction of Floor 1 are divided into those that propagate towards the back of Stage 4 and those that propagate towards the front of Stage 4. In other words, from the perspective of Stage 4, the vibrations are perceived as moving away. On the other hand, from the perspective of the area behind Floor 1, which is located further away than the last row of Floor 1, the vibrations are perceived as moving closer. Therefore, the minimum reduction frequency f1 changes due to the Doppler effect.

[0037] The minimum reduced frequency f1 at which a change occurs is f1 ^ Expressed as follows: the minimum reduction frequency f1 when the difference in sound arrival time is not considered, and the minimum reduction frequency f1 when the difference in sound arrival time is considered.^ are respectively represented by formulas (4) and (5).

[0038] [Math.]]

[0039] In formula (5), Δθ λ1 / 2 represents a phase difference of sound. f1 satisfying formula (4) and f1 satisfying formula (5) ^ are respectively frequencies at which the content inside the parentheses of the sine term equals π. Therefore, the conditional expression shown in formula (6) is obtained from formulas (4) and (5).

[0040] [Math.]]

[0041] Since wavelength λ1 is represented by formula (2), it can be transformed into formula (7).

[0042] [Math.]]

[0043] Therefore, multiplying both sides of formula (7) by V s / nd gives the minimum reduction frequency f1 that accounts for the sound arrival time difference ^ which is represented by formula (8).

[0044] [Math.]]

[0045] That is, the minimum reduction frequency f1 when the sound arrival time difference is taken into consideration ^ changes by ±V s / 340 relative to the original minimum reduction frequency f1. In the present embodiment, in order to further reduce the minimum reduction frequency f1 to achieve vibration reduction, a negative sign is employed. V representing the amount of change in the minimum reduction frequency f1 sRegarding the sign of / 340, a plus sign indicates the direction from which the sound is approaching, and a minus sign indicates the direction from which the sound is moving away. Therefore, equation (8) means that vibrations propagating in the direction away from floor 1, i.e., towards the back of stage 4, along the depth direction of floor 1, are suppressed.

[0046] Also, ±V s The value of / 340 does not depend on the minimum reduction frequency f1, so the smaller the minimum reduction frequency f1, the greater the -V with respect to the minimum reduction frequency f1. s The effect of reducing the frequency by the / 340 term becomes relatively larger. In equation (8), -V s The term with / 340 is called the "sound arrival time difference term".

[0047] From the above considerations, if there is a specific area 6 where vibration reduction is to be desired around the acoustic facility 10, the stage 4, floor 1, and specific area 6 should be arranged along the extension of the line connecting the acoustic facility 10 and the specific area 6. In this case, the stage 4, floor 1, and specific area 6 should be arranged in the order of stage 4, floor 1, and specific area 6 along the extension of the line connecting the acoustic facility 10 and the specific area 6, so that the specific area 6 is located behind the stage 4.

[0048] Figure 3 shows an example of the arrangement of Stage 4, Floor 1, and Specific Area 6 according to this disclosure. In Figure 3, extension line 7A indicates the line connecting Stage 4 and Floor 1. Extension line 7A connects the center of Stage 4 and the center of Floor 1.

[0049] As shown in Figure 3, along extension line 7A, a vibration reduction range 8 is created behind stage 4 where vibrations are reduced compared to other areas around acoustic facility 10. Therefore, by setting the relative positions of stage 4, floor 1, and specific area 6 such that extension line 7A points in the direction of the specific area 6 where vibration reduction is desired, as viewed from floor 1, vibrations in the specific area 6 can be reduced compared to vibrations in other surrounding areas.

[0050] <Analysis example> Below 2.5 people / m2 This study examines the vibrations caused by the vertical movement of spectators in a floor 1 with a length of 40m in depth and 30m in width, which can accommodate 3000 spectators at a given spectator density. In all cases, the vibration propagation velocity V s Let's assume it's 100 [m / s].

[0051] For the sake of explanation, the case in which the minimum reduction frequency f1 is calculated without considering the difference in sound arrival time will be referred to as "conventional technology." On the other hand, the case in which the minimum reduction frequency f1 is calculated considering the difference in sound arrival time ^ The method used to calculate this is referred to as "the technology of this disclosure."

[0052] [Case 1] The minimum reduced vibration frequency f1 for the conventional technology when 3,000 spectators perform in-phase excitation on a floor 1 in which support members 9 are arranged at 10 [m] intervals, and the minimum reduced vibration frequency f1 for the technology of this disclosure when 3,000 spectators perform in-phase excitation on a floor 1 in which support members 9 are arranged at 5 [m] intervals. ^ Compare the two. Assume that both floor 1s are isolated from the surface ground 2A.

[0053] Figure 4 shows an example of the configuration of Floor 1 in Example 1. Figure 4(A) shows an example of the configuration of Floor 1 in the prior art, and Figure 4(B) shows an example of the configuration of Floor 1 in the technology of this disclosure.

[0054] Figure 5 shows an example of the vertical acceleration of the ground surface at specified distances from the front center end P of the floor along the vibration propagation direction X shown in Figure 4. The front center end P of the floor is the intersection of the side 1A in the width direction of floor 1 that is closer to stage 4 and the extension line 7A (see Figure 3). The vibration propagation direction X indicates the depth direction of floor 1. That is, the vibration propagation direction X in Figure 4(B) indicates the same direction as the extension line 7A in Figure 3.

[0055] Figure 5(A) shows the vertical acceleration of the ground surface at a point 50m away from the front center edge P of the floor. Figure 5(B) shows the vertical acceleration of the ground surface at a point 100m away from the front center edge P of the floor. Figure 5(C) shows the vertical acceleration of the ground surface at a point 150m away from the front center edge P of the floor. Figure 5(D) shows the vertical acceleration of the ground surface at a point 200m away from the front center edge P of the floor.

[0056] In Figures 5(A) to 5(D), the vertical axis represents the vertical acceleration of the ground surface, and the horizontal axis represents the frequency. In Figures 5(A) to 5(D), a higher position on the vertical axis indicates a greater vertical acceleration of the ground surface, and a higher position on the horizontal axis indicates a higher frequency. In Figures 5(A) to 5(D), the vertical acceleration of the ground surface is labeled "acceleration". In Figures 5(A) to 5(D), graph 12A (solid line graph) represents the analysis results of the conventional technology, and graph 12B (dotted line graph) represents the analysis results of the technology of this disclosure.

[0057] Focusing on the frequencies around 2 Hz in Figures 5(A) to 5(D), the minimum reduction frequency f1 in the technology of this disclosure ^ It can be seen that this is lower than the minimum reduction frequency f1 in the conventional technology.

[0058] When calculating the theoretical minimum reduction frequency f1 in the prior art and the theoretical minimum reduction frequency f1 in the art of this disclosure, the theoretical minimum reduction frequency f1 in the prior art is obtained from equations (2) and (3) as 100 / (5×10)=2[Hz]. On the other hand, the theoretical minimum reduction frequency f1 in the art of this disclosure is obtained from equations (2) and (3) as 100 / (9×5)≈2.22[Hz]. The reason why the theoretical minimum reduction frequency f1 in the art of this disclosure is higher than the theoretical minimum reduction frequency f1 in the prior art is that the spacing of the support members 9 shown in Figure 4(B) is shorter than the spacing of the support members 9 shown in Figure 4(A).

[0059] However, in the technology of this disclosure, as shown in equation (8), the time difference term of sound arrival is taken into consideration with respect to the minimum reduction frequency f1. Therefore, the minimum reduction frequency f1^ V s The frequency decreases by approximately 0.29 Hz (1 / 340 = 100 / 340). That is, the minimum reduced frequency f1 in the technology of this disclosure. ^ This corresponds to 1.93 [Hz]. The analysis results shown in Figures 5(A) to 5(D) represent the theoretical situation.

[0060] Based on the above, suppose, for example, that the spacing between the support members 9 would ideally be 10 [m], but due to design constraints, a situation arises where the spacing between the support members 9 must be shorter than 10 [m]. Even in such a case, the technology of this disclosure can reduce vibrations in the specific area 6 compared to the conventional technology by arranging the floor 1, stage 4, and specific area 6 in the order of floor 1, stage 4, and specific area 6 along extension line 7A.

[0061] [Case Study 2] The minimum reduced vibration frequency f1 for the conventional technology when 3,000 spectators perform in-phase excitation on a floor 1 isolated from the surface ground 2A, with support members 9 arranged at 5m intervals, and the minimum reduced vibration frequency f1 for the technology of this disclosure when 3,000 spectators perform in-phase excitation on a floor 1 not isolated from the surface ground 2A. ^ Compare them.

[0062] Figure 6 shows an example of the configuration of floor 1 in Example 2. Figure 6(A) shows an example of the configuration of floor 1 in the prior art, and Figure 6(B) shows an example of the configuration of floor 1 in the technology of this disclosure. In Example 2, to which the technology of this disclosure is applied, floor 1 is directly supported by the surface ground 2A, and there is no support member 9 in floor 1 shown in Figure 6(B). Thus, since floor 1 in the technology of this disclosure is not isolated from the surface ground 2A, it is in a linear excitation state along the vibration propagation direction X.

[0063] Figure 7 shows an example of the vertical acceleration of the ground surface at specified distances from the front center end P of the floor along the vibration propagation direction X shown in Figure 6. Note that the vibration propagation direction X in Figure 6(B) is the same direction as the extension line 7A in Figure 3.

[0064] Figure 7(A) shows the vertical acceleration of the ground surface at a point 50m away from the front center edge P of the floor. Figure 7(B) shows the vertical acceleration of the ground surface at a point 100m away from the front center edge P of the floor. Figure 7(C) shows the vertical acceleration of the ground surface at a point 150m away from the front center edge P of the floor. Figure 7(D) shows the vertical acceleration of the ground surface at a point 200m away from the front center edge P of the floor.

[0065] Similar to Figure 5, in Figures 7(A) to 7(D), the vertical axis represents the vertical acceleration of the ground surface, and the horizontal axis represents the frequency. In Figures 7(A) to 7(D), a higher position on the vertical axis indicates a larger vertical acceleration of the ground surface, and a higher position on the horizontal axis indicates a higher frequency. In Figures 7(A) to 7(D), the vertical acceleration of the ground surface is labeled "acceleration". Also in Figures 7(A) to 7(D), graph 12A (solid line graph) represents the analysis results of the conventional technology, and graph 12B (dotted line graph) represents the analysis results of the technology of this disclosure.

[0066] Focusing on the frequencies around 2.2 [Hz] in Figures 7(A) to 7(D), the minimum reduction frequency f1 in the technology of this disclosure ^ Is the minimum reduction frequency f1 in the conventional technology approximately the same frequency, or is the minimum reduction frequency f1 ^ It can be seen that this is lower than the minimum reduction frequency f1 in the conventional technology.

[0067] Calculating the theoretical minimum reduction frequency f1 in the prior art and the theoretical minimum reduction frequency f1 in the art of this disclosure, the theoretical minimum reduction frequency f1 in the prior art is 100 / 40 ≈ 2.22 [Hz] from equations (2) and (3). On the other hand, in the art of this disclosure, since the vibration is linearly excited in the vibration propagation direction X, the wavelength λ1 of the vibration in this case is 40 [m]. Therefore, the theoretical minimum reduction frequency f1 in the art of this disclosure is 100 / 40 = 2.5 [Hz] from equation (3). The reason why the theoretical minimum reduction frequency f1 in the art of this disclosure is higher than the theoretical minimum reduction frequency f1 in the prior art is that floor 1, shown in Figure 6(B), is not isolated from the surface ground 2A.

[0068] However, in the technology of this disclosure, as shown in equation (8), the time difference term of sound arrival is taken into consideration with respect to the minimum reduction frequency f1. Therefore, the minimum reduction frequency f1 ^ V s The frequency decreases by approximately 0.29 Hz (1 / 340 = 100 / 340). That is, the minimum reduced frequency f1 in the technology of this disclosure. ^ This corresponds to 2.21 Hz. The analysis results shown in Figures 7(A) to 7(D) represent the theoretical situation.

[0069] Based on the above, suppose a situation arises where, for example, although it would be desirable to isolate Floor 1 from the surface ground 2A, design constraints prevent this. Even in such a case, the technology of this disclosure can reduce vibrations in the specific area 6 compared to the conventional technology by arranging Floor 1 and Stage 4 in the order of Floor 1, Stage 4, and specific area 6 along extension line 7A.

[0070] Further analysis investigated the relationship between the shape of floor 1 and the frequency in specific region 6 in both Case 1 and Case 2. The results showed that when floor 1 is rectangular and its depth is greater than its width, the frequency in specific region 6 is reduced.

[0071] [Case Study 3] In Case 1 and Case 2, the minimum reduced vibration frequency f1 in the specific region 6 is determined when the specific region 6 is located behind the stage 4 and the stage 4 and floor 1 are positioned such that the specific region 6 lies on the extension line 7A connecting the stage 4 and floor 1. ^ However, it was explained that the vibration reduction is lower than the minimum reduction frequency f1 in conventional technology. Case study 3 explains the range in which the vibration reduction effect can be obtained.

[0072] For the sake of explanation, Figure 3 shows the shape of the vibration reduction range 8, where the vibration reduction effect is obtained, as a rectangle represented by extension lines 7B, which are extensions of both sides of floor 1 along extension line 7A, and the back side 4A of stage 4 along the width direction of floor 1. However, the vibration reduction range 8 is not limited to the range of the rectangle formed behind stage 4. The vibration reduction range 8 extends beyond the range of the rectangle formed behind stage 4.

[0073] Figure 8 shows an example of the vibration reduction range 8 in the technology of this disclosure. The depth of floor 1 is 40 [m] and the width of floor 1 is 30 [m]. As shown in Figure 8, the vibration reduction range 8 includes a rectangular region 8A represented by the side 1A that is closer to stage 4 among the widthwise sides of floor 1 opposite stage 4, and extension line 7B. The vibration reduction range 8 also includes a triangular region 8B represented by extension line 7B and extension line 7C that intersects extension line 7B at a 30-degree angle and starts from points P1 and P2, which are the endpoints of side 1A of floor 1, respectively. In other words, the technology of this disclosure can reduce vibrations in the triangular region 8B as well as in the rectangular region 8A representing the projected range of floor 1, compared to vibrations in other surrounding areas. The projected range of floor 1 is the range that floor 1 passes through when stage 4 is moved parallel to floor 1 along extension line 7A in a certain direction.

[0074] To support this fact, we will examine the vertical ground acceleration at each point within the vibration reduction range 8 shown in Figure 8, when 3,000 spectators are subjected to in-phase excitation on floor 1, which is not isolated from the surface ground 2A. Figure 9 shows an example of measurement points for vertical ground acceleration. As an example, we will measure the vertical ground acceleration at specified distances along extension line 7A and extension lines 7B, 7C, and 7D, which start from point P1. Extension line 7D is a line that intersects extension line 7B at an angle of 15 degrees.

[0075] The starting point for measuring the specified distance on extension lines 7B, 7C, and 7D is point P1. Point P1 is referred to as the "front apex end of the floor P1". The starting point for measuring the specified distance on extension line 7A is the front center end of the floor P. For the sake of explanation, the front center end of the floor P and the front apex end of the floor P1 are collectively referred to as the "front end of the floor".

[0076] Figures 10 and 11 show examples of vertical ground surface acceleration at each measurement point shown in Figure 9.

[0077] Figure 10(A) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 25m away from the front edge of the floor. Figure 10(B) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 50m away from the front edge of the floor. Figure 10(C) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 75m away from the front edge of the floor. Figure 10(D) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 100m away from the front edge of the floor.

[0078] Furthermore, Figure 11(A) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 125m away from the front edge of the floor. Figure 11(B) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 150m away from the front edge of the floor. Figure 11(C) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 175m away from the front edge of the floor. Figure 11(D) shows the vertical acceleration of the ground surface along extension lines 7A to 7D at a point 200m away from the front edge of the floor.

[0079] As previously explained, in Figures 10 and 11, the starting point for measuring the specified distance along extension line 7A is the front apex end P1 of the floor. Similarly, the starting point for measuring the specified distance along extension lines 7B to 7D is the front apex end P1 of the floor.

[0080] In Figures 10(A) to 10(D) and 11(A) to 11(D), the vertical axis represents the vertical acceleration of the ground surface, and the horizontal axis represents the frequency. In Figures 10(A) to 10(D) and 11(A) to 11(D), the higher the position on the vertical axis, the greater the vertical acceleration of the ground surface, and the further to the right the position on the horizontal axis, the higher the frequency.

[0081] Furthermore, in Figures 10(A) to 10(D) and Figures 11(A) to 11(D), graph 12C (the second shortest dotted line graph) represents the analysis results on extension line 7A, and graph 12D (the shortest dotted line graph) represents the analysis results on extension line 7B. Additionally, graph 12E (the dashed-dot line graph) represents the analysis results on extension line 7D, and graph 12F (the longest dotted line graph) represents the analysis results on extension line 7C.

[0082] For each of Figures 10(A) to 10(D) and Figures 11(A) to 11(D), if we focus on the frequency range from 1.5 [Hz] to 3 [Hz], the minimum reduction frequency f1 in Graph 12D ^ This is the minimum reduced frequency f1 in Graph 12C. ^ It can be seen that it is almost the same. Note that the minimum reduction frequency f1 in graphs 12E and 12F ^ This is the minimum reduced frequency f1 in Graph 12C. ^ Although it tends to be higher compared to, the minimum reduction frequency f1 ^ The discrepancy is small enough that it is not noticeable to the senses.

[0083] In other words, when the stage 4 and floor 1 are positioned such that a specific region 6 is behind the stage 4 and the specific region 6 lies on the extension line 7A connecting the stage 4 and floor 1, the vibration reduction range 8 extends beyond the rectangular area formed behind the stage 4. An example of the extended range is the triangular region 8B formed by the extension line 7C, which starts from points P1 and P2 indicating the ends of side 1A of floor 1 and intersects the extension line 7B at a 30-degree angle, and the extension line 7B.

[0084] The angle formed by the boundaries of the vibration reduction range 8 that intersect extension line 7B at points P1 and P2, respectively (angles of 15 degrees and 30 degrees in the above example), is called the "effective angle." The effective angle is affected by the length of floor 1 in the depth direction, and decreases as the length of floor 1 in the depth direction increases. In order to include the entire specific region 6 in the vibration reduction range 8, it is desirable to have a certain effective angle. Specifically, it is preferable that the effective angle is approximately 15 degrees or more. Analysis showed that when the depth of floor 1 is 1.5 times the width of floor 1, the effective angle decreases to approximately 15 degrees. Therefore, it is better to keep the depth of floor 1 to 1.5 times the width of floor 1 or less.

[0085] Furthermore, the technology disclosed herein is also applicable to floors 1 whose width is greater than their depth. In this case as well, in order to improve the vibration reduction effect in a specific region 6, it is preferable to keep the width of floor 1 to 1.5 times or less the depth of floor 1.

[0086] Although one form of the acoustic facility 10 has been described above using embodiments, the disclosed form of the acoustic facility 10 is merely an example, and the form of the acoustic facility 10 is not limited to the scope described in the embodiments. Various modifications or improvements can be made to the embodiments without departing from the gist of this disclosure, and such modified or improved forms are also included within the technical scope of the disclosure.

[0087] The following are additional notes relating to this disclosure.

[0088] (Note 1) The stage and the floor are positioned such that a specific area where vibration reduction is desired is located behind the stage, along the extension of the line connecting the stage where performers perform and the floor where the audience is seated. Sound facilities.

[0089] (Note 2) The floor is arranged such that the first length of the floor in the extension direction is longer than the second length of the floor in the intersecting direction that intersects the extension direction. The sound facilities described in Appendix 1.

[0090] (Note 3) The first length of the floor is 1.5 times or less the second length of the floor. The acoustic facilities described in Appendix 2.

[0091] (Note 4) The floor is arranged such that the first length of the floor in the extension direction is shorter than the second length of the floor in the intersecting direction that intersects the extension direction. The sound facilities described in Appendix 1.

[0092] (Note 5) The second length of the floor is 1.5 times or less the first length of the floor. The acoustic facilities described in Appendix 4.

[0093] (Note 6) The stage and the floor are positioned such that a specific area where vibration reduction is desired is located behind the stage, along the extension of the line connecting the stage where performers perform and the floor where the audience is seated. How to arrange acoustic facilities. [Explanation of symbols]

[0094] 1 floor 1A Floor edge 2 Ground 2A Surface ground 2B Supporting ground 3. Arrows indicating the position of the excitation point. 4 stages 4A Stage edge 5 (5A~5F) Arrows indicating floor locations 6 Specific areas 7A~7D extension line 8. Vibration reduction range 8A rectangular area 8B Triangular area 9 Support members 10. Sound Facilities Graph showing the analysis results of vibrations from 12A to 12F. λ1 wavelength P1, P2 End points of the edges of the floor V s Vibration propagation speed X vibration propagation direction d Excitation point interval f1, f1 ^ Minimum reduced frequency n number of excitation points

Claims

1. The stage and the floor are positioned such that a specific area where vibration reduction is desired is located behind the stage, along the extension of the line connecting the stage where performers perform and the floor where the audience is seated. Sound facilities.

2. The floor is arranged such that the first length of the floor in the extension direction is longer than the second length of the floor in the intersecting direction that intersects the extension direction. The acoustic facility according to claim 1.

3. The first length of the floor is 1.5 times or less the second length of the floor. The acoustic facility according to claim 2.

4. The stage and the floor are positioned such that a specific area where vibration reduction is desired is located behind the stage, along the extension of the line connecting the stage where performers perform and the floor where the audience is seated. How to arrange acoustic facilities.

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