JP2006208273A - Acoustic field simulation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic field simulation system which uses a virtual image method, performing high computation accuracy in combination with a sound line tracking method realizing low computational load, computes a sound environment in a house having a lot of walls so as to compensate for its diffraction phenomenon, while significantly reducing the computational load, and can obtain successful result that is more approximate to the actual measured value. <P>SOLUTION: The acoustic field simulation system is composed of an input means for inputting building information and sound source information; a path-computing means which computes a path of a sound line by reflection, by using the sound line tracking method and the virtual image method; and a sound pressure level computing means which computes sound pressure level along the path of the sound line. The path-computing means uses a sound receiving point in the virtual image method as a position of a virtual sound source and computes the path, by using the sound line tracking method. The sound pressure level computing means uses the sound pressure, computed by the virtual image method about the sound receiving point as the sound pressure of the virtual sound source, and computes the sound pressure level by using the sound line tracking method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sound field simulation system using both a ray tracing method and a virtual image method, and relates to a system for simply and rapidly calculating sound transmission in a building having a complicated shape such as a house.

  Conventionally, simulation of sound transmission using a computer has been performed. In the past, wave analysis using the finite element method or boundary element method was the mainstream, but because wave analysis requires a large amount of computation, it takes a long time to calculate and requires a lot of computer resources. There's a problem.

  Therefore, in recent years, a calculation method called a sound ray method is often used. This is to express sound transmission by quantizing the sound emitted from the sound source and expressing it as a sound ray, and calculating the sound pressure of the sound ray that is reflected and arrives. Furthermore, the sound ray method can be roughly divided into a sound ray tracking method and a virtual image method.

  In the sound ray tracing method, first, a large number of sound rays are set at a predetermined interval from a sound source in basically all directions, and intersections between the sound ray vectors and walls are determined. Then, the direction of the sound ray to be reflected is determined according to the angle of the vector and the wall, and the next intersection is determined. If the reflection has reached a predetermined number of times, no further reflection is made (the end of the sound ray is the intersection with the wall). When the intersections and paths are determined for all sound rays, the sound pressure level is calculated along each path while considering attenuation due to distance and attenuation due to reflection. The calculation of the sound pressure level may be performed before the calculation of all the paths is completed (for example, every time one sound ray path is determined).

  In the virtual image method, a sound receiving point is set, a virtual image of a sound source is created at a position symmetrical to the barrier, and a point where the sound ray connecting the virtual image and the sound receiving point intersects the barrier is obtained as an intersection (reflection point). When considering two-time reflection and three-time reflection, first, a virtual image is set at a position symmetrical to the barrier that can be reflected, and then a virtual image of the virtual image is created for the barrier that can be reflected. In response, a superimposed virtual image is created. The calculation of the sound pressure level is the same as described above. By calculating in this way, the sound ray density is stabilized, so that the calculation accuracy can be improved and the calculation amount can be greatly reduced.

  Both the ray-tracing method and the virtual image method are calculated using sound rays, and the calculation is relatively simple and the amount of calculation is small compared to the wave analysis method. It is known that this is an effective means for performing the above. In particular, the sound ray method is suitable for analysis of a closed space such as a hall. For example, as in JP-A-6-11386, it is possible to obtain a simple and good simulation result in combination with the virtual image method. .

Japanese Patent Laid-Open No. 06-011386 Japanese Patent Application Laid-Open No. 07-092018

  By the way, among the sound ray methods, the sound ray tracking method and the virtual image method have different characteristics. Since the ray tracing method has a small amount of calculation, the calculation load does not increase so much even if the reflection order is increased. However, the farther away from the sound source, the lower the density of the sound ray, and the variation in density increases depending on the location. Since the virtual image method calculates the sound ray for the sound receiving point, the density of the sound ray is less likely to occur, so the sound ray density is stable, the calculation accuracy is improved, and the result is obtained only for a specific sound receiving point (observation range). If you want to get it, you can greatly reduce the amount of calculation. However, when calculating the entire layout of a house, it is not as much as wave diffraction, but it is much more computationally intensive than the ray tracing method, and the calculation load increases exponentially if the reflection order is increased. There is.

  The sound ray method, in principle, seeks transmission of sound by reflection, and ignores the wave nature of sound. In reality, sound circulates and is transmitted by the diffraction phenomenon to the part behind the sound insulation wall such as the wall with respect to the sound source, but it is difficult to reproduce the diffraction phenomenon by the sound ray method. For this reason, the sound ray method is suitable for simulation of a space having a relatively simple shape such as a hall, but it is not suitable for considering sound transmission in a house having a complicated shape. If the reflection order of the sound ray is increased, the sound ray can reach the shadowed part, but increasing the reflection order by the virtual image method is not realistic because the calculation amount increases exponentially. .

  In the past, proposals have been made to supplement the analysis of diffraction phenomena using the acoustic ray method. For example, in Patent Document 2 (Japanese Patent Laid-Open No. 07-092018), a secondary sound ray is generated when a sound ray collides with a wall, but a secondary wave is generated only when the sound ray collides with an edge of the wall. Thus, a proposal has been made that the diffraction phenomenon can be reproduced while greatly reducing the amount of calculation.

  However, in the proposal according to Patent Document 2, the number of sound rays that collide with the edge of the wall using the sound ray tracking method is extremely small, or even the existence thereof is uncertain, and the reliability of the calculation result is ensured. It ’s difficult.

  Therefore, the present invention uses the virtual image method with high calculation accuracy and the ray tracing method with low calculation load to greatly reduce the amount of calculation, while reaching the sound ray in the sound environment in a house with many barriers. An object of the present invention is to provide a sound field simulation system that can significantly reduce the range that is not used and can obtain a good result closer to the actual measurement value.

  In order to solve the above problems, a typical configuration of a sound field simulation system according to the present invention is based on input means for inputting building information and sound source information, and reflection of sound rays using sound ray tracking methods and virtual image methods. Path calculating means for calculating a path, and sound pressure level calculating means for calculating a sound pressure level along the path of the sound ray, wherein the path calculating means determines the sound receiving point in the virtual image method as the position of the temporary sound source. The sound pressure level calculation means calculates the sound pressure calculated by the virtual image method for the sound receiving point as the sound pressure of the temporary sound source, and further calculates the sound by the sound ray tracking method. The pressure level is calculated. In this way, the calculation is first performed with a high-accuracy virtual image method, and the calculation result is further calculated by the ray tracing method, so that the calculation amount does not increase greatly even if the reflection order is increased, and the calculation load is increased. Good results can be obtained without increasing.

  Further, in the building information, when the sound-insulating wall where the sound collides is defined as the sound-insulating edge, the sound receiving point as the temporary sound source is the virtual image method among the many sound receiving points. The sound line connecting the sound receiving point and the sound source is closest to the sound insulation end. The end portion of the sound insulating wall that can be diffracted means a corner portion or a protruding portion of the wall when there is a space beyond the sound insulating wall as viewed from the sound source. By configuring in this way, high-accuracy virtual image method is used to calculate the part where the sound ray easily reaches from the sound source, and the sound ray tracking method is used to calculate the part where the sound ray from the sound source is difficult to reach. This can be done, and the range where the sound ray does not reach can be greatly reduced with a small amount of calculation.

  The sound receiving point as the temporary sound source is a sound receiving point at which a sound ray emitted from the sound source arrives without being reflected. This is for the purpose of simplifying the calculation or facilitating the setting of the temporary sound source.

  In addition, the path of the sound ray calculated from the temporary sound source using the sound ray tracking method by the route calculation means excludes a region where the sound ray emitted from the sound source reaches without reflection. . For the part where the sound ray reaches directly from the sound source, it is possible to perform the calculation by the highly accurate virtual image method. Therefore, the calculation amount is reduced by omitting the calculation of the sound ray tracking method for the part. Because it can.

  In addition, a predetermined observation range is set, and calculation results by either method are selected based on the density of sound rays passing through the observation range in each path calculation of the sound ray tracking method and the virtual image method, or both It is characterized by comprising an adjustment calculation means for calculating the final sound pressure by combining the calculation results of In any method, when the number of sound rays is small, the reliability of the calculation result is lowered. Therefore, a more appropriate result can be obtained by apportioning the calculation method.

  In addition, the adjustment calculation means holds a setting for selecting a calculation result by one of the methods for the sound ray density of the sound ray tracking method and the virtual image method, or combining both the calculation results. The method selection table is provided. It is an example of the structure for selecting the calculation result by any method.

  According to the present invention, by using the virtual image method with high calculation accuracy and the ray tracing method with low calculation load, the amount of calculation is greatly reduced, and the sound ray is reduced in the sound environment in a house with many barriers. Even the range that does not reach can be greatly reduced, and a good result closer to the actual measurement value can be obtained.

  An embodiment of a sound field simulation system according to the present invention will be described. FIG. 1 is a schematic configuration diagram of a sound field simulation system according to the present embodiment, FIG. 2 is a diagram for explaining a sound ray arrival limit by the virtual image method, and FIG. 3 is a diagram for explaining a sound ray arrival state by the sound ray tracking method. FIG. 4 is a diagram for explaining the selection of the calculation method, and FIG. 5 is a flowchart for explaining the characteristic operation of this embodiment.

  As shown in FIG. 1, this system includes a system main body 1, input means 2, and output means 3. The input unit 2 is a unit for inputting information necessary for calculation, and includes an input device such as a keyboard and a mouse, a storage medium, a network, and the like. The output means 3 outputs a calculation result, and includes a monitor for displaying a screen, a printer for printing, a recording medium for saving as data, and the like.

  The storage area 11 of the system body 1 stores building information and sound source information input from the input means 2. The building information includes the layout of the building, spatial coordinate information such as the dimensions and wall thickness of each room, and barrier information such as the material and type of the wall, as well as the arrangement, sound absorption rate, and reflectance of the furniture. . The sound source information includes the spatial coordinates (position) of the sound source and the characteristics of the sound source (frequency characteristics, directivity, intensity). The system body 1 also includes a reflectance database 12, and stores the reflectance for the wall material and type. It should be noted that the reflectance database 12 does not necessarily have to be incorporated in the main body, and can be supplied by a recording medium such as a network type or a CDROM as necessary.

  Further, the system main body 1 includes a path calculation means 13, a temporary sound source setting means 14, a sound pressure level calculation means 15, an adjustment calculation means 16, and a method selection table 16a for calculating a sound ray path. The route calculation means 13 calculates the path of the sound ray and calculates the intersection of the barrier and the sound ray. In this embodiment, the route can be calculated by both the sound ray tracking method and the virtual image method. Yes. The sound pressure level calculation means 15 calculates the sound pressure level at the intersection (reflection point) with the wall, the end point of the sound ray in the sound ray tracking method, and the sound receiving point in the virtual image method along the calculated sound ray path. The calculation is performed using the intensity of the sound source and the reflectance of the wall. The temporary sound source setting means 14 sets a temporary sound source as a sound source in the sound ray tracking method, and the adjustment calculation means 16 apportions the calculation results by the virtual image method and the sound ray tracking method, and detailed operations will be described later. To do. Each element of the system main body 1 is connected to the CPU 10 to perform predetermined processing.

  In practice, the storage area 11 is a storage means such as a RAM or a hard disk, and the reflectance database 12 and the method selection table 16a are tables (structure data) stored in the storage means. The path calculation means 13, the temporary sound source setting means 14, the sound pressure level calculation means 15, and the adjustment calculation means 16 are modules realized by programs, and are read by the CPU 10 and perform predetermined operations as hardware.

  Since the calculation methods of the ray tracing method and the virtual image method are already well known, a detailed description is omitted here. The simple explanation is as described in the section of the prior art.

  Next, characteristic processing of the present invention will be described with reference to FIGS. A floor plan 20 shown in FIG. 2 shows a floor plan of a house in the present embodiment, which is generally U-shaped as a whole, and is an image in which two rooms are connected by a corridor. A sound source 21 is arranged at the corner of one room.

  FIG. 2 is a diagram for explaining the reach limit of sound rays by the virtual image method. Here, by using the virtual image method, the sound receiving points 22 are set at regular intervals (in this embodiment, 1 m intervals), and the end of the sound ray 23 is always the sound receiving point 22, The intersecting point (reflection point) is not limited to the sound receiving point 22, but is an arbitrary position. In the figure, the region where the sound ray 23 reaches is represented by the positive part A, and the non-reachable range is represented by the shaded part B. The sound ray 23 shows only the boundary between the positive part A and the shadow part B, and the other sound rays in the positive part A are not shown.

  FIG. 2A shows a range in which the sound ray 23 can reach directly without reflection. As can be seen from the drawing, the end of the wall 20a among the sound insulating walls that the sound collides with is actually the end where the sound can be diffracted, and this is referred to as the sound insulating end 20b. However, since the diffraction phenomenon cannot be reproduced by the sound ray method, a shadow B as shown in the figure occurs.

  FIG. 2 (b) shows the reach range of the sound ray when the reflection order in the virtual image method is 1 (reflecting once). Similarly, FIG. 2 (c) and FIG. 2 (d) show the reflection order respectively. The reachable range in the case of 2 and 3 is shown. From these figures, it can be seen that by increasing the reflection order, the reachable range (positive portion A) is widened even with a floor plan 20 having a complicated shape. However, since the setting of the virtual image is complicated in the virtual image method, there is a problem that the calculation amount (calculation time) increases exponentially by increasing the reflection order.

  Therefore, in this embodiment, a specific sound receiving point in the virtual image method is used as a temporary sound source, and further calculation is performed by the ray tracing method, and these results are apportioned and considered, without further increasing the calculation load. Get accurate results.

  FIG. 3 is a diagram for explaining a state where a sound ray reaches by the sound ray tracking method. Since the sound ray method is calculated by generating sound rays at regular intervals (angles) from the sound source, there is no sound receiving point, and how much sound (sound ray x each sound within a given observation range) Pressure) is transmitted. The observation range can be set, for example, as a 30 cm square area in the horizontal plane.

  FIG. 3A is a diagram for explaining setting of the temporary sound source. In the present embodiment, as shown in FIG. 2A, the temporary sound source 22a has a sound ray 23 connecting the sound receiving point 22 and the sound source 21 in the virtual image method among the many sound receiving points 22, and the sound insulation end 20b. Is the closest one. And it is preferable that the sound ray 24 set in the temporary sound source 22a is only directed to the shadow B.

  FIG. 3B shows a range in which the sound ray 24 can reach directly without reflection. Considering that the temporary sound source 22a is the first intersection in the virtual image method, it should be compared with the double reflection in FIG. 2C, but it can be seen that the reachable range (the positive part A) is much wider. Similarly, FIGS. 3C and 3D show the reach ranges when the reflection orders are 1 and 2, respectively. In the floor plan 20 of this embodiment, as shown in FIG. 3D, it can be seen that the shadow B disappears due to the reflection twice by the ray tracing method.

  Here, since the accuracy of the virtual image method is higher, it is clear that it is preferable to calculate a wide range by the virtual image method as much as possible. Therefore, in this embodiment, the temporary sound source is a sound receiving point that can be reached directly without being reflected in the virtual image method. However, a sound receiving point that can be reached by one reflection and two reflections may be used as the temporary sound source. . As a result, the sound ray tracing method can be started from a deeper part of the shadow that can be diffracted. However, since the number of temporary sound sources increases as the reflection order increases, the calculation load increases even with the sound ray tracing method, and there is a possibility that setting of the temporary sound sources may be omitted.

  Further, it is conceivable that the temporary sound source setting means 14 using any sound receiving point 22 as a temporary sound source is automatically specified by calculation. However, the logic for automatically determining the sound receiving point to be a temporary sound source from the shape becomes complicated. On the other hand, the number of temporary sound sources is not so large. Therefore, the temporary sound source setting means 14 is used as an input means so that the temporary sound source is directly designated by hand, or the sound insulation end 20b is manually specified and the sound receiving point for the sound ray closest to this is calculated. It may be configured.

  The position of the temporary sound source 22a is determined by selecting the sound receiving point 22, but the sound pressure can be determined only after the sound pressure level is calculated by the virtual image method. Therefore, it is necessary to calculate the sound pressure level by the virtual image method at least before calculating the sound pressure level by the sound ray tracking method.

  2 and 3, only the range where the sound ray reaches is shown, but the denseness is also generated in the positive part A. In this embodiment, therefore, a plurality of reflection orders are set even in the virtual image method, and calculation is performed by overlapping the sound ray tracking method. Then, the calculation result by either method is selected according to the number of sound rays that have reached the predetermined observation range, or both calculation results are combined.

  FIG. 4A is a graph in which a sound experiment is performed in a predetermined reverberation room, a simulation calculation is performed by a virtual image method and a sound ray tracking method, and the sound ray density and the calculation result are compared with actual measurement values. The difference in the number of sound rays is caused by the density of sound rays depending on the part. As can be seen from the figure, the actual measured value is constant 60.5 dB, whereas the virtual image method requires about five sound rays, and after that, the measured value is almost consistent with the actual measured value. The sound ray tracing method requires about seven sound rays until it approaches the actual measurement value, and if it increases beyond that, an error occurs with the actual measurement value. For these reasons, the virtual image method is more reliable even when the number of sound rays is small (not enough), and if there are a sufficient number of sound rays, only the result of the virtual image method is sufficient. Recognize.

  Therefore, in this embodiment, which calculation result is adopted is determined as shown in FIG. 4B according to the number of virtual image methods and ray tracing methods existing in the same observation range. That is, when there are five or more sound rays by the virtual image method, only the result of the virtual image method is employed. When there is no sound ray by the virtual image method, the result of the sound ray tracking method is adopted. When the number of sound rays by the virtual image method is 4 or less, both calculation results are prorated. For example, ((Sound pressure by virtual image method x Number of sound rays by virtual image method) + (Sound pressure by sound ray tracking method x Number of sound rays by sound ray tracking method)) / Total number of sound rays A result in consideration of reliability can be obtained.

  Such a determination criterion is preferably set in advance as the method selection table 16a, and the adjustment calculation means 16 (program) reads this to output the final sound pressure level.

  The operation of the system described above will be described with reference to the flowchart shown in FIG. First, using the input means 2, the building information of the house (sound absorption coefficient such as floor plan and wall, reflectance, furniture type and arrangement information, etc.) is input (S1), and sound source information and reflection order are input (S2). . The reflection order is set for each of the virtual image method and the sound ray tracing method. At this time, the sound receiving point 22 is also set, and the sound receiving point (or the sound insulation end portion 20b) to be the temporary sound source 22a is specified.

  Then, the route calculation means 13 performs route calculation by the virtual image method (S3). The calculation is repeated until the set reflection order is reached (S4). As described above, the temporary sound source 22a is set to the sound receiving point 22 that can reach without reflection, but the calculation by the virtual image method is set to a higher-order reflection order. Next, the route calculation means 13 again performs route calculation by the ray tracing method (S5). The calculation is repeated until the set reflection order is reached (S6).

  Then, the sound pressure level calculation means 15 calculates the sound pressure at the sound receiving point in the virtual image method (S7). At this time, since the sound pressure level of the temporary sound source 22a is also calculated, the sound pressure level of the ray tracing method is also calculated using this (S8).

  The adjustment calculation means 16 selects a calculation result with reference to the method selection table 16a for each observation range, or calculates the final sound pressure level (S9). The calculation result is output from the CPU 10 by the output means 3 (S10).

  By configuring as described above, it is possible to eliminate the shadow area where the sound ray does not reach at all without increasing the calculation load.

  In other words, the calculation load increases exponentially when the reflection order is increased in order to eliminate the shadow using only the virtual image method. Even if it is suppressed, the genital area can be extinguished. In addition, the calculation accuracy can be improved by calculating together with the virtual image method as compared with the case of calculating using only the ray tracing method.

  Furthermore, compared to the case where the calculation is simply performed by the two methods, the sound ray tracing method is performed using a sound receiving point in the middle of the virtual image method as a temporary sound source, so that the portion where the sound ray is difficult to reach by the virtual image method is concentrated on the sound ray. It can be calculated by the tracking method. In particular, by using the temporary sound source as the sound receiving point where the sound ray is close to the sound insulating end where sound can be diffracted in the sound insulating wall, the shadow can be extinguished with an extremely small number of reflections, and the calculation load is dramatically reduced. can do.

  The present invention can be used for a sound field simulation system in a building with many barriers such as a house.

It is a schematic block diagram of the sound field simulation system which concerns on an Example. It is a figure explaining the reach limit of the sound ray by a virtual image method. It is a figure explaining the state which the sound ray reaches | attains by a sound ray tracking method. It is a figure explaining selection of a calculation method. It is a flowchart explaining the characteristic operation | movement of a present Example.

Explanation of symbols

A ... Yangon B ... Shadow 1 ... System body 2 ... Input means 3 ... Output means
10 ... CPU
11 ... Storage area
12… Reflectance database
13: Route calculation means
14 Temporary sound source setting means
15… Sound pressure level calculation means
16… Adjustment calculation means
16a ... Method selection table
20… floor plan
20a ... wall
20b ... Sound insulation end
21… Sound source
22… Sound receiving point
22a ... Temporary sound source
23… Sound ray
24… Sound ray

Claims (6)

Input means for inputting building information and sound source information;
A route calculation means for calculating a route by reflection of the sound ray using the ray tracing method and the virtual image method;
A sound pressure level calculating means for calculating a sound pressure level along the path of the sound ray,
The route calculation means further calculates a route using the ray tracing method with the sound receiving point in the virtual image method as the position of the temporary sound source,
The sound pressure level calculating means calculates the sound pressure level in the sound ray tracing method using the sound pressure calculated in the virtual image method for the sound receiving point as the sound pressure of the temporary sound source, and further in the sound ray tracing method. system. In the building information, if the end where sound can diffract out of the sound insulating wall where the sound collides is a sound insulating end,
The sound receiving point as the temporary sound source is characterized in that, among a large number of sound receiving points, a sound ray connecting the sound receiving point and the sound source in the virtual image method is closest to the sound insulation end. Item 1. A sound field simulation system according to item 1. The sound field simulation system according to claim 1, wherein the sound receiving point as the temporary sound source is a sound receiving point at which a sound ray emitted from the sound source arrives without being reflected. The path of the sound ray calculated from the temporary sound source using the sound ray tracking method by the route calculating means excludes an area where the sound ray emitted from the sound source reaches without reflection. 1. The sound field simulation system according to 1. Set a predetermined observation range,
Based on the density of sound rays passing through the observation range in each path calculation of the ray tracing method and the virtual image method,
2. The sound field simulation system according to claim 1, further comprising adjustment calculation means for calculating a final sound pressure by selecting a calculation result by any method or combining both calculation results. The adjustment calculation means is a method that holds a setting for selecting a calculation result by either method for the sound ray density of the sound ray tracking method and the virtual image method, or by combining both calculation results. The sound field simulation system according to claim 5, further comprising a selection table.

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