JP3258148B2 - Sound simulation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic simulation apparatus used for checking a sound environment.

[0002]

2. Description of the Related Art When an object is placed in a room, the sound environment in the room changes and a sound problem may occur. For example, in a central control room such as a power plant, a large display panel greatly affects the sound environment of the central control room. Depending on the arrangement of the display panel, the sound is concentrated only at one location of the central control room, which may have an adverse effect on the operator, which is a problem.

[0003] Acoustic simulation using a computer is widely known as an effective means for checking such a sound environment problem at the stage of interior design. This acoustic simulation is used when designing a room acoustic space where a high-quality acoustic effect is desired, such as a concert hall or a listening room. Therefore, when performing an acoustic simulation, highly accurate analysis is required. As an acoustic simulation method, a method of solving a wave equation under complicated boundary conditions to obtain an exact solution has been adopted. I have.

[0004]

However, such an acoustic simulation has a drawback that the calculation time is extremely long. When performing the above-described acoustic simulation of the central control room, a long calculation time is required for each change in the arrangement of the display panel, so that it is not possible to evaluate the acoustics in an interactive design.

[0005] Therefore, a geometric acoustic simulation method that ignores the wave nature of sound and focuses only on the reflection and absorption processes of sound has been considered. However, in this method, if there is no restriction on the reflection surface in the environment space, even a reflection surface having little influence is to be calculated, and efficient simulation cannot be performed. Also, if there is no restriction on the sound transmission path, the calculation must be performed for all paths, which is inefficient. Further, since no consideration is given to the wave nature of the sound, it is not possible to simulate a low-frequency sound with a weak directivity, such as a low motor sound.

Further, conventionally, a straight line has been used as a method for visually displaying a sound transmission path, but has a drawback that it is difficult to visually recognize the sound intensity and the like. As described above, the conventional acoustic simulation method using a computer has a drawback that even if strict calculations can be performed, it takes too much calculation time. The method of ignoring wave characteristics is also inefficient because there is no standard for selecting reflection surfaces and sound transmission paths, it is not possible to simulate low-frequency sound, and furthermore, the sound transmission path is easy to understand visually. And there was no way to display the sound intensity.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to increase the calculation speed as much as possible, have sufficient accuracy for objective evaluation, and visually understand the way of sound transmission. Acoustic simulation for easy display
It is to provide a device .

[0008]

[0009]

An acoustic simulator according to the present invention is provided.
In the environment space where the 3D model is located, the position and the sound intensity of one or more sound sources, the position of one or more sound receiving points, and the reflecting surface that affects the sound environment are specified. An input unit to calculate the path and the distance from the sound source directly or from the reflection surface to the sound receiving point after being reflected by the reflection surface, and calculate the sound reception by the distance and the reflectance of the reflection surface where the reflection occurred. Calculating means for calculating the intensity of the sound at the point and adding the intensity of the sound reaching the sound receiving point via each of the calculated paths; And a display unit whose graphic display is changed in accordance therewith.

[0010]

[0011]

According to the acoustic simulation apparatus of the present invention ,
The sound reflection surface only affects the sound environment.
Calculation of the transmission path of the
Rations can be done. In addition, since the sound transmission path and the sound intensity can be visually displayed in an easily understandable manner, the sound effect can be evaluated intuitively.

[0012]

The first embodiment of the present invention will be described below. 1 is a flowchart showing an acoustic simulation method, FIG. 2 is a block diagram showing a configuration of an acoustic simulation apparatus, FIGS. 3 and 4 are diagrams showing an example of an acoustic environment space of a three-dimensional model, and FIG. FIG. 4 is a diagram illustrating a two-dimensional acoustic environment in two cases.

First, in FIG. 2, reference numeral 1 denotes a CPU (Central Processing Unit) that controls the entire apparatus. The CPU 1 has a ROM (Read Only Memory) 2 in which a program for executing the acoustic simulation method shown in the flowchart of FIG. 1 is built, and an R for storing various acoustic data.
AM (random access memory) 3, sound source position,
An input unit 4 for designating a sound intensity, a position of a sound receiving point, and a reflection surface, and a CRT display unit 5 for displaying a sound transmission path and a sound intensity by computer graphics are connected.

First, an acoustic simulation method will be described with reference to the flowchart of FIG. First,
A three-dimensional position of one or a plurality of sound sources is designated from the input unit 4 (step S1). Next, one or more sound receiving points 3
The dimensional position is designated from the input unit 4 (step S2).

Next, in the environment space where the three-dimensional model is arranged, a sound reflection surface is designated from the input unit 4 (step S3). Here, the method of designating the reflection surface of the sound is such that the reflection surface is directly specified by designating, for example, the coordinates of the vertices of a rectangle in the environment space that is particularly desired to be examined or that is likely to be affected, as data. Like that.

For example, a large display panel 1 as shown in FIG.
When the user wants to check the acoustic effect by the number 1, the rectangular reflecting surfaces A, B, and C in the hatched portion are designated. When the three-dimensional model is composed of surfaces, only a surface having a certain size (area) or more may be designated as a reflection surface. That is,
As shown in FIG. 4, when assuming a three-dimensional model composed of several surfaces of a desk, surfaces A, B, C, and D are designated as reflection surfaces, and surface E and the like have other areas. Since it is smaller, it is out of symmetry as a reflection surface.

After specifying the position of the sound source, the intensity of the sound, the position of the sound receiving point, and the reflecting surface as described above,
The sound transmission path and its distance are calculated (step S
4). Here, the transmission path and its distance are calculated by applying the specular reflection law on the reflection surface.

FIG. 5 shows that the sound source S and the sound receiving point R are each 1
FIG. 2 is a two-dimensional diagram illustrating a case where there are two reflective surfaces (A, B) to simplify the description. In FIG.
SA is a symmetrical point of S with respect to the reflecting surface A, SB is a symmetrical point of S with respect to the reflecting surface B, SAB is a symmetrical point with respect to the reflecting surface B of SA, and SBA is a symmetrical point with respect to the reflecting surface A of SB. In this case, routes from the sound source S to the sound receiving point R are routes a, b,
c and d. The path a is a path that reaches directly from S, and the paths b and c are paths that are primarily reflected by the reflecting surfaces A and B, respectively. The path d is a path of the secondary reflection in which the sound emitted from the sound source S is reflected by the reflection surface A, subsequently reflected by the reflection surface B, and reaches the sound receiving point R. For example, the route d is calculated by obtaining the points P2 and P1. This route is configuration route 1,
It is composed of 2 and 3, and the calculation process is 1 → 2 →
The order is 3. However, the route is blocked by another plane,
In some cases, it is not possible to establish a path, so it is necessary to check whether each of the constituent paths (1, 2 and 3) intersects with another plane.

Next, the sound intensity at the sound receiving point R is calculated for each path (step S5). It is assumed that the sound intensity I attenuates in inverse proportion to the square of the distance L of the path, and that when the sound is reflected by the reflecting surfaces, it is weakened by the reflectance R of each reflecting surface. For example, when the sound reaches the sound receiving point R at a distance L after the primary reflection, assuming that the original sound intensity is Io and the attenuation parameter is D, the sound intensity is I = R · Io · D / ( LL).

Then, the sound intensity at the sound receiving point R is calculated by superimposing the sound intensities on the routes calculated as described above (the routes a, b, c and d in FIG. 5). (Step S6). The path and the sound intensity calculated in this way are sent to the CRT display unit 5 and displayed in computer graphics. The manner of display will be described later.
Next, an acoustic simulation method according to a second embodiment of the present invention will be described with reference to the flowchart in FIG. The second embodiment shows a flowchart of an acoustic simulation method when a condition of a transmission path (for example, only primary reflection) is specified. The specification of the route condition is specified from the input unit 4.

The flowchart of FIG. 6 is obtained by inserting a step S10 for designating a path condition between steps S3 and S4 of the flowchart of FIG. The processing of steps S1 to S3 in FIG.
Since they are exactly the same as 1 to S3, detailed description is omitted.

Then, the reflection order (number of times) is specified from the input unit 4 as the specification of the path condition in step S10. For example, in the case of FIG. 5, if the condition is specified as a path to the primary reflection, the path d is not calculated. The setting of this reflection order is optional. In particular, when there are many reflection surfaces in the environment space and the number of paths to be calculated is large, it is necessary to increase the calculation efficiency by using conditions up to the secondary reflection. Comes.

Also, instead of specifying the path condition by the reflection order, a certain standard is set for the intensity of the sound reaching the sound receiving point, and a path having a sound intensity equal to or larger than the loudness is targeted. A method is also conceivable. In other words, a reference may be given to the distance of the route, and if the distance of the route exceeds a certain reference distance during the calculation of step 4 (see FIG. 5 for calculating the configuration route), the calculation of this route may be terminated. . For example, FIG.
In the case of, if the sum of the distances of the constituent paths 1 and 2 exceeds the reference distance in the calculation process of the path d, the calculation of the path d may be terminated without calculating the constituent path 3. .

As described above, according to the second embodiment, since the route condition can be designated, the calculation efficiency can be improved. Next, a third embodiment of the present invention will be described with reference to the flowchart of FIG. In the third embodiment, the acoustic simulation method is changed according to the type of the sound source S (high frequency, low frequency). The flowchart of FIG. 7 includes a determination block (step S21) for determining the frequency of the sound source S before step S1 of the flowchart of FIG. 1. If the sound source S has a high frequency, the processes of steps S1 to S6 are performed. When the sound source S has a low frequency, ambient sound processing (step S31) is performed.

That is, it is determined whether the frequency of the sound source S is high or low (step S21). If it is determined that the frequency of the sound source S is high, steps S1 to S6 in the flowchart shown in FIG. By the same processing, a sound path calculation is performed.

On the other hand, if it is determined in step S21 that the sound source S has a low frequency, it is processed as an ambient sound (step S31). Here, the frequency of the sound source is determined by determining a threshold value of the frequency. If the frequency is higher than this frequency, the frequency is determined to be high; For example, the threshold value of this frequency is set to 256 cycles / sec (piano central key C) or before or after that (200 to 300 cycles / sec).
And

If the frequency of the sound output from the sound source S is not a fixed frequency but has a plurality of frequency components, the frequency component having the highest peak is represented as the frequency of the sound source, or the average is taken. What is necessary is just to make it represent by the average value. For example, if the sound source is a conversation sound,
Normally, when the frequency is higher than the above-described frequency threshold, a sound path calculation is performed as a simulation.

On the other hand, when it is determined in step S21 that the sound source S has a low frequency, the sound intensity at the sound receiving point is related to the reflection surface in consideration of the low frequency diffraction phenomenon. Ambient sound processing is performed to calculate that the sound is weakened in inverse proportion to the square of the distance from the sound source (step S31).

The determination in step 21 may be made automatically by collecting the sound of the sound source S with a microphone (not shown), or the operator may know the frequency characteristics of the sound source S. If so, it may be designated from the input unit 4 as appropriate.

As described above, according to the third embodiment, the acoustic simulation method is made different depending on the frequency of the sound source S. Therefore, regardless of the magnitude of the frequency of the sound source S,
Accurate acoustic simulation can be performed.

In the first to third embodiments described above, the sound transmission path and its strength are calculated, but the sound transmission path and its strength are calculated as shown in FIG. 8 and FIG.
The T display unit 5 may be displayed in color by computer graphics.

FIG. 8 illustrates a case where the transmission path of the sound reflected by the reflection surface A is indicated by a straight line. A straight line is color-coded according to the reflection order (the number of times) of the path, so that the way of sound transmission is visually easy to understand. Further, the intensity of the color is changed according to the intensity of the sound of each path. For example,
In the case of supporting full color, the sound intensity I is I = 1.0
(= MAX) and red (R, G, B) = (256,0,
0), I = 0.5 and pink (R, G, B) = (256, 1)
28, 128) (that is, G, B = 256 × (1.0-I)), the sound intensity can be visually understood.

FIG. 9 illustrates a case where the transmission path of the sound reflected by the reflection surface A is indicated by a truncated cone. In this case, the radius of the bottom surface of the truncated cone indicates the sound intensity. For example, if the radius r is r = ro when I = 1.0, then r = ro
× (1.0-I).

As described above, the sound transmission path and intensity are graphically displayed on the CRT display unit 4.
The operator can visually determine the path from the sound source S to the sound receiving point R.

In the first to third embodiments, the sound source S
And the number of sound receiving points R is one,
The same applies to a case where there is one sound source S and there are a plurality of sound receiving points R, a case where there are a plurality of sound sources S and one sound receiving point R, and a case where there are a plurality of sound sources S and there are a plurality of sound receiving points R. it can.

[0036]

As described above in detail, according to the present invention, the sound transmission path is calculated only on the surface which affects the sound environment as the sound reflection surface, so that efficient sound simulation can be performed. Since the conditions for the path are specified, efficient sound simulation can be performed, and low-frequency sound is processed as ambient sound, so that a realistic sound simulation can be performed and the sound transmission path and sound intensity can be visually determined. Since it can be displayed clearly, the sound effect can be evaluated intuitively.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an acoustic simulation method according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an acoustic simulation apparatus that employs the acoustic simulation method of the present invention.

FIG. 3 is a diagram illustrating an example of an acoustic environment space of a three-dimensional model.

FIG. 4 is a diagram illustrating an example of an acoustic environment space of a three-dimensional model.

FIG. 5 is a diagram showing a two-dimensional acoustic environment when there are two reflecting surfaces.

FIG. 6 is a flowchart showing an acoustic simulation method according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an acoustic simulation method according to a third embodiment of the present invention.

FIG. 8 is a diagram for explaining visualization of a sound transmission path.

FIG. 9 is a diagram for explaining visualization of a sound transmission path and sound intensity.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... ROM, 3 ... RAM, 4 ... Input part, 5
... CRT.

Claims (1)

(57) [Claims] In an environment space in which a three-dimensional model is arranged, a reflection surface which affects the position and sound intensity of one or a plurality of sound sources, the position of one or a plurality of sound receiving points, and a sound environment is defined. An input unit to be specified; a path directly from the sound source or reflected from the reflection surface to the sound receiving point and a distance thereof, and the reception unit calculates the distance and the reflectance of the reflection surface where the reflection occurred. Calculating means for calculating the sound intensity at the sound point and adding the sound intensity arriving at the sound receiving point via each of the calculated paths; and A display unit for changing a graphic display according to the strength.