JP4157856B2 - Acoustic reflection path discrimination method, computer program, acoustic reflection path discrimination apparatus, and acoustic simulation apparatus - Google Patents

Description

  The present invention relates to an acoustic reflection path discriminating method, a computer program, an acoustic reflection path discriminating apparatus, and an acoustic simulation apparatus. More specifically, the present invention relates to a sound reflection path obtained by a virtual image method, and when the acoustic characteristics are obtained, The present invention relates to a method for determining sex.

  When a sound source is placed in a space such as a hall or studio and the output sound is heard at a certain sound receiving point in the space, sound waves are emitted from the sound source in various directions. Only the sound wave propagated through the propagation path to reach is heard as sound at the sound receiving point. The space through which sound propagates is called a sound field, and the propagation path is called a sound ray. The propagation path from the sound source to the sound receiving point includes a direct path connecting the sound source and the sound receiving point with a straight line and a reflection path reflected on the wall surface. Further, the reflection path includes a higher-order reflection path that is reflected twice or more in addition to the primary reflection path that is reflected once on the wall surface and reaches the sound receiving point.

  The sound reaching the sound receiving point is attenuated and delayed according to the propagation path length. Further, in the case of the sound that has reached through the reflection path, the volume, tone color, and phase are changed according to the material of the wall surface at the time of reflection on the wall surface. For this reason, even if the sound is emitted from the same sound source, the amplitude, frequency, and phase differ for each propagation path when the sound receiving point is reached.

  Therefore, given the position and material of the wall surface defining the space, the position of the sound source and the sound receiving point, and if each propagation path from the sound source to the sound receiving point can be obtained accurately, the sound source The acoustic characteristics of the space showing the relationship between the output sound and the listening sound at the sound receiving point can be obtained. In general, it is relatively easy to obtain a direct path. Therefore, if a reflection path can be obtained, sound propagation characteristics can be obtained for each sound ray including the direct path. Can be sought. If the acoustic characteristics are obtained in this way, an acoustic simulation for reproducing the listening sound at the sound receiving point can be performed based on the output sound of the sound source without using the real space.

  FIG. 12 is an explanatory diagram showing an example of a conventional method for obtaining a reflection path, in which (a) shows the sound ray tracing method and (b) shows the virtual image method. In the figure, S is a sound source, R is a sound receiving point, P is a reflection point on the wall surface, and S 'is an imaginary sound source. Conventionally known methods of geometrically determining the reflection path are the ray tracing method and the virtual image method. The sound ray tracing method radiates a number of sound rays with different directions from the sound source S, tracks the subsequent trajectory of each sound ray, and adopts only the sound ray passing near the sound receiving point R as a reflection path. It is a method to do. On the other hand, the virtual image method is a method in which a virtual image (virtual sound source S ′) of a sound source related to a reflection surface is obtained and a path connecting the virtual sound source S ′ and the sound receiving point R with a straight line is used as a reflection path.

The virtual image method has the advantage that the reflection path can be obtained accurately. However, if the number of wall surfaces increases and the reflection order increases, the number of virtual sound sources increases exponentially, and the amount of calculation accordingly increases. It has the disadvantage of increasing dramatically. On the other hand, in the case of the ray tracing method, the reflection path can be obtained with a relatively small amount of calculation, but the reflection path cannot be obtained accurately. Further, for example, Patent Document 1 discloses a method for obtaining a reflection path by combining a sound ray tracking method and a virtual image method.
JP-A-6-11386

FIG. 13 is a diagram illustrating an example of a reflection path obtained by the virtual image method. First, an imaginary sound source S ′ is obtained from the sound source S. The imaginary sound source S ′ is obtained as a point that is plane-symmetric with the sound source S with respect to the wall surface. That is, a point on the normal line of the wall surface including the sound source S and on the side opposite to the sound source S and having the same distance from the wall surface is defined as the imaginary sound source S ′. Next, a reflection point P ₁ is obtained as a point where a path connecting the imaginary sound source S ′ and the sound receiving point R ₁ intersects the wall surface. Accordingly, SP ₁ R ₁ is obtained as a reflection path from the sound source S to the sound receiving point R ₁ .

In the same manner, SP ₂ R ₂ is obtained as a reflection path from the sound source S to the sound receiving point R ₂ . However, the reflection point P ₂ because is located outside the finite wall W, the reflected path of the SP ₂ R _2, is not actually present. That is, the wall surface is ineffective as a reflecting surface, and accurate acoustic characteristics cannot be obtained by obtaining acoustic characteristics including the reflecting path. Therefore, when the virtual image method is used, it is necessary to determine whether or not the wall surface W is effective as a reflection surface for each reflection on the wall surface W and to determine whether or not the reflection path actually exists.

  As described above, in the virtual image method, when the reflection order increases, the reflection path also increases exponentially, so that the number of operations for determining whether the wall surface is valid or invalid increases exponentially. For this reason, a method for determining whether or not a wall surface is effective as a reflecting surface is important in calculating a reflection path by a virtual image method. However, Patent Document 1 described above does not specifically describe such a determination method.

  The present invention has been made in view of the above circumstances, an acoustic reflection path determination method capable of efficiently determining an acoustic reflection path obtained by a virtual image method, and a computer program for determining an acoustic reflection path An object of the present invention is to provide an acoustic reflection path discrimination device and an acoustic simulation device. In particular, it is an object to determine the effectiveness of an acoustic reflection path with a small amount of calculation based on the three-dimensional coordinates of each vertex, sound source, and sound receiving point that define a wall surface.

The acoustic reflection path discriminating method according to the present invention is a method for operating an acoustic reflection path discriminating apparatus that discriminates the effectiveness of a reflection path obtained by a virtual image method based on the coordinates of each vertex defining a polygonal reflecting surface piece. And based on the order of the vertices that appear when the outer periphery of the reflecting surface piece is traced in one direction, the reflecting surface piece of the reflecting surface piece is reflected at a reflecting point where the reflecting path intersects the plane including the reflecting surface piece. Based on an angle calculation step for obtaining a signed angle formed by two adjacent vertices, an angle integration step for obtaining a sum of the signed angles obtained between all adjacent vertices, and a sum of the signed angles, A first determination step of determining whether or not the reflection point exists on the reflection surface piece.

  In addition to the above configuration, in the acoustic reflection path determination method according to the present invention, the angle calculation step includes a first inner product calculation step for obtaining an inner product of vectors connecting two adjacent vertices and the reflection point, and a first inner product. Based on the inner product obtained in the operation step, the step for obtaining the absolute value of the angle, the outer product operation step for obtaining the outer product vector of the vector connecting the adjacent vertex and the reflection point, and the outer product obtained in the outer product operation step. A second inner product calculating step for obtaining an inner product of the vector and a reference vector intersecting the reflecting surface piece and obtaining a sign of the angle.

  In addition to the above-described configuration, the acoustic reflection path determination method according to the present invention includes the normal vector of the reflecting surface piece.

  In addition to the above configuration, the acoustic reflection path determination method according to the present invention further includes a second determination step of determining whether or not there is a reflecting surface piece that does not include the reflection point on the reflection path. Is done.

Further, the acoustic simulation apparatus according to the present invention is based on the coordinates of each vertex defining the polygonal reflecting surface piece, and the reflection path obtained by the virtual image method intersects the plane including the reflecting surface piece related to the derivation. Based on the order of the vertices appearing when the outer periphery of the reflecting surface piece is traced in one direction, the reflection point calculating means for obtaining the coordinates of the reflecting points to be used is a vector connecting two adjacent vertices and the reflecting point. A first inner product computing means for obtaining an inner product; an absolute value calculating means for obtaining an absolute value of an angle formed by the adjacent vertexes at the reflection point based on the inner product obtained by the first inner product computing means; and the adjacent vertexes and obtains the product computation means for obtaining the outer product vector of a vector connecting the reflection point, the inner product of the reference vector which intersects the outer product vector and the reflecting surface pieces obtained by the product computation means, the A second inner product calculating means for obtaining a sign of the degree; a judging means for judging whether or not the reflecting point is present on the reflecting surface piece based on the sum of the signed angles; and a judgment result in the judging means. Then, using the reflection surface piece, the propagation characteristic calculation means for obtaining the propagation characteristic of the reflection path from the sound source to the sound receiving point and the propagation characteristic of the reflection path are used to generate the listening sound at the sound receiving point from the output sound of the sound source. And a listening sound generating means.

  According to the present invention, it is possible to efficiently discriminate the acoustic reflection path obtained by the virtual image method. In particular, the effectiveness of the acoustic reflection path can be determined with a small amount of calculation based on the three-dimensional coordinates of each vertex, sound source, and sound receiving point that define the wall surface. For this reason, the acoustic characteristic from the sound source to the sound receiving point can be obtained at high speed. In addition, acoustic simulation can be executed at high speed.

Embodiment 1 FIG.
FIG. 1 is a functional block diagram showing a configuration example of an acoustic simulation apparatus according to Embodiment 1 of the present invention. This acoustic simulation device is an arithmetic processing device that can obtain the listening sound at the sound receiving point R from the output sound of the sound source S without using a real space, and is realized as software executable on a computer, for example. can do.

  The acoustic simulation apparatus includes an acoustic characteristic calculation unit 10, a wall surface data storage unit 11, and a listening sound generation unit 12. The acoustic characteristic calculation unit 10 obtains an acoustic characteristic from the sound source S to the sound receiving point R by arithmetic processing based on the coordinate positions of the sound source S and the sound receiving point R and the position and characteristics (reflection characteristics) of the wall surface W. ing. The wall surface data storage unit 11 holds data of the wall surface W used for this acoustic characteristic calculation. The listening sound generation unit 12 generates the listening sound data at the sound receiving point R based on the output sound data of the sound source S by the calculation process using the acoustic characteristics obtained by the acoustic characteristic calculation unit 10.

  The acoustic characteristic calculation unit 10 includes a direct path calculation unit 20, a reflection path calculation unit 21, a reflection path determination unit 22, propagation characteristic calculation units 23 and 24, and a synthesis unit 25. The direct path calculation unit 20 and the reflection path calculation unit 21 are input with the three-dimensional coordinates of the sound source S and the sound receiving point R, and the direct path and the reflection path are obtained, respectively.

  The direct path calculation unit 20 obtains a path connecting the sound source S and the sound receiving point R with a straight line as the direct path. At that time, it is determined whether or not there is an obstacle on the direct route based on the wall surface data in the wall surface data storage unit 11, and if there is an obstacle, the direct route is invalidated. When the direct path is valid, the propagation characteristic calculation unit 23 obtains the sound propagation characteristic of the direct path. Note that the propagation characteristic of the direct path consists of amplitude attenuation and phase delay according to the path length, and the frequency component does not vary.

  In the reflection path calculation unit 21, a reflection path related to each wall surface W held in the wall surface data storage unit 11 is obtained. The reflection path obtained by the reflection path calculation unit 21 includes not only the primary reflection path but also secondary or higher reflection paths. The reflection path determination unit 22 determines whether or not the reflection point P in these reflection paths exists in the wall surface W, and determines whether or not the reflection path is valid.

  The propagation characteristic calculation unit 24 obtains the sound propagation characteristic for the reflection path determined to be valid by the reflection path determination unit 22. The propagation characteristic by the reflection path includes amplitude attenuation and phase fluctuation at the reflection point P in addition to amplitude attenuation and phase delay according to the path length. Note that these fluctuations at the reflection point are determined by the material of the wall surface W, and characteristic data based on the material of the wall surface W is held in the wall surface data storage unit 11.

  The synthesizing unit 25 synthesizes the propagation characteristics of the direct path and the reflection path obtained by the propagation characteristic calculating units 23 and 24, and obtains the propagation characteristics of the sound from the sound source S to the sound receiving point R through various paths. Can do. That is, the acoustic characteristic calculation unit 10 can obtain an acoustic characteristic from the sound source S to the sound receiving point R.

  The listening sound generation unit 12 generates listening sound data at the sound receiving point R from the output sound data of the sound source S using the acoustic characteristics obtained by the acoustic characteristic calculation unit 10. For example, when the acoustic characteristic calculation unit 10 determines the acoustic characteristic as an impulse response, the listening sound generation unit 12 performs a calculation process of convolving the output sound data of the sound source S with the impulse response, and the listening sound at the sound receiving point R is performed. Is generated.

For this reason, if the acoustic simulation apparatus is used, the sound source S is arranged at an arbitrary position in the sound field defined by the wall surface data storage unit 11 and an arbitrary sound is output from the sound source S. The listening sound at the point R can be reproduced. For example, if the positions of the right and left ears of a person are the receiving points R ₁ and R ₂ and the respective listening sounds are generated, how to hear the sound at an arbitrary position in the space without using the real space Can be experienced. It is also possible to experience the difference in the way of hearing by changing the position and type of the speaker as the sound source. It can also be used for acoustic design of buildings such as halls and studios.

  FIG. 2 is a diagram illustrating an example of a direct path and a reflection path. The direct route Q1 is a route SR that connects the sound source S and the sound receiving point R with a straight line. When there is no obstacle, the direct route SR is obtained by the direct route calculation unit 20, and the propagation characteristic thereof is obtained by the propagation characteristic calculation unit 23.

  The reflection path Q2 is a primary reflection path related to the wall surface W. The imaginary sound source S ′ is obtained for the wall surface W, and is obtained by the reflection path calculation unit 21 as a path connecting the imaginary sound source S ′ and the sound receiving point R with a straight line. It is done. If the point where the straight line S′R intersects the wall surface W is the reflection point P, the original reflection path SPR is equivalent to the straight path S′R.

  In the reflection path calculation unit 21, the imaginary sound source S ′ is obtained for all the wall surfaces W held in the wall surface data storage unit 11, and a primary reflection path that connects each imaginary sound source S ′ and the sound receiving point R with a straight line. Desired. At this time, the imaginary sound source S ′ is obtained as three-dimensional coordinates that are plane-symmetric with the sound source S with respect to the wall surface W.

  The reflection path determination unit 22 obtains a reflection point P where each reflection path obtained in the reflection path calculation unit 21 intersects a plane including a wall surface W related to derivation of the reflection path (a plane having an infinite extent), It is determined whether or not the reflection point P exists in the wall surface W, and it is determined whether or not the reflection path is valid. The wall surface W is a reflection surface (reflection surface piece) having a finite area, and is a polygonal plane defined by at least three or more vertex data a1 to a4. The reflection path determination unit 22 performs the above determination based on these vertex data. A specific method for determining the effectiveness of the reflection path will be described later.

FIG. 3 is a diagram showing an example of the secondary reflection path. When obtaining the secondary reflection path reflected in the order of the wall surfaces W ₁ and W ₂ , the reflection path calculation unit 21 first obtains the three-dimensional coordinates of the imaginary sound source S ′. Imaginary sound source S 'is a virtual image of the sound source S regarding the wall surface W _1, it is determined as a point where the wall surface W ₁ becomes a sound source S and the plane of symmetry. Next, the three-dimensional coordinates of the imaginary sound source S ″ are obtained. Imaginary sound source S '' is the imaginary sound source S about the wall W ₂ 'is a virtual image, is determined as a point where the wall surface W ₂ becomes imaginary sound source S' and plane symmetry. A path connecting the imaginary sound source S ″ and the sound receiving point R with a straight line is obtained as a secondary reflection path. If the point where the straight line S ″ R intersects the plane including the wall surface W ₂ is the reflection point P ₂ and the point where the straight line P ₂ S ′ intersects the plane including the wall surface W ₁ is the reflection point P ₁ , The reflection path SP ₁ P ₂ R is equivalent to the path S ″ R.

The reflection path determination unit 22 determines whether or not these reflection points P ₁ and P ₂ exist in the wall surfaces W ₁ and W ₂ , respectively. As a result, when the reflection point P ₁ does not exist in the wall surface W ₁ or the reflection point P ₂ does not exist in the wall surface W ₂ , the reflection path does not actually exist, so it is determined to be invalid. . Therefore, the propagation characteristic calculation unit 24 does not require the propagation characteristic for a reflection path that does not exist.

  The third and higher order reflection paths are also obtained by the reflection path calculation unit 21 in exactly the same manner as in the case of the secondary reflection path, and when any reflection point P does not exist in the wall surface W, the reflection path determination unit 22 Is determined as an invalid reflection path.

  FIG. 4 is an explanatory diagram showing the basic principle for determining the effectiveness of the reflection path. (A) in the figure shows an example when the reflection point P exists in the wall surface W, and (b) in the figure shows an example when the reflection point P exists outside the wall surface W.

The wall surface W consists of a polygonal plane, and is defined by the three-dimensional coordinates and order of the vertices a _{1 to} a ₅ that define the polygon. The order of the vertex a ₁ ~a _5, a sequence in which each vertex a ₁ ~a ₅ appears when tracing the polygonal outer peripheral top in one direction. These data defining the wall surface W are stored in the wall surface data storage unit 11. The three-dimensional coordinates of the reflection point P are obtained by the reflection path determination unit 22 based on the reflection path obtained by the reflection path calculation unit 21 and the data in the wall surface data storage unit 11.

Here, a vector from the reflection point P toward each vertex a _j (j = 1 to 5) is V _j, and a signed angle of the vector V _{j + 1} with respect to V _j is θ _j . That is, the absolute value of θ _j is the angle formed by the adjacent vertices a _j and a _{j + 1} at the reflection point P, and the sign thereof is obtained as the rotation direction from the vertex a _j centering on the reflection point P to a _{j + 1} . It is done. For example, a counterclockwise rotation is positive and a clockwise rotation is negative.

When a certain reference point is traced in one direction on the outer periphery of the wall surface W and the wall surface W is rotated once, if the reflection point P exists in the wall surface W, the reference point is 1 around the reflection point P. If the reflection point P is outside the wall surface W, the reference point does not go around the reflection point P once. Therefore, as shown in (a), when the reflection point P exists in the wall surface W, the sum of the signed angles θ _j is 2π or −2π. On the other hand, as shown in (b), when the reflection point P exists outside the wall surface W, the sum of the signed angles θ _j is zero. That is, the sum of the angles θ _j is expressed by the following equation (1).

The reflection path determination unit 22 determines whether or not the reflection point P exists in the wall surface W using the above equation (1), and determines whether or not the reflection path exists. In theory, the sum of the angles θ _j does not take an intermediate value between ± 2π and 0. However, considering the calculation error, a positive value (for example, π) smaller than 2π is set as the threshold θth, and the absolute value of Σθ _j The determination can be made by comparing the value with the threshold value θth.

Next, a method for obtaining the signed angle θ _j will be described. The absolute value of the signed angle θ _j can be obtained based on the inner product (scalar product) of the vectors V _j and V _{j + 1} . Further, the sign of the signed angle θ _j can be obtained based on the outer product (vector product) of the vectors V _j and V _{j + 1} .

FIG. 5 is an explanatory diagram of a method for obtaining the signed angle θ _j . Inner product _{V j} · _V j _{+ 1} of the vector _{V j} and _{V j + 1} is represented by formula (2) using the angle theta _j of both vectors. If this equation (2) is modified, the angle θ _j is expressed by equation (3) using the inverse function of cos. Each component of the vector V _{j in} the x-axis direction, the y-axis direction, and the z-axis direction can be obtained from the three-dimensional coordinates of the vertex a _j and the reflection point P. These components are expressed as x _j , y _j , z _j and Then, the angle θ _j can be obtained from the equation (4).

However, in general, the cos function is a function in which the relationship cos θ _j = cos (−θ _j ) is established, and therefore only the absolute value of the angle θ _j can be obtained from the equation (4) using the inverse function. . For this reason, the sign of the angle θ _j is separately obtained based on the outer product of the vectors V _j and V _{j + 1} .

Cross product vector _{U j = V j × V j} + 1 of the vector _{V j} and _{V j + 1} are the two vectors _{V j,} a vector orthogonal to both of _{V j + 1,} the orientation of the screw from the vector _{V j} to the vector _{V j + 1} It is defined as the direction in which the screw advances when it is rotated (so-called right screw direction). That is, the outer product vector U _j is a vector perpendicular to the wall surface W, and its direction corresponds to the sign of the angle θ _j .

Therefore, if the direction of the outer product vector U _j is determined, the sign of the angle θ _j can be obtained. The direction of the outer product vector U _j can be determined by obtaining the inner product with an arbitrary reference vector N perpendicular to the wall surface W. That is, if the outer product vector U _j and the reference vector N have the same direction, the inner product U _j · N becomes positive, and if the direction is opposite, it becomes negative. For this reason, the sign of the inner product U _j · N can be used as the sign of the angle θj. The reference vector N is preferably a normal vector of the wall surface W, but may not necessarily be a normal vector as long as the vector intersects the wall surface W.

The x, y, and z axis components of the outer product vector U _j are x _uj , y _uj , and z _uj, and the x, y, and z axis components of the vector V _j are x _j , y _j , and z _j . In this case, the outer product vector U _j is expressed by the following equation (5) using each component of the vectors V _j and V _{j + 1} .

Therefore, if each component of the reference vector N in the x, y, and z-axis directions is x _n , y _n , z _n , the inner product of the outer product vector Uj and the reference vector N can be obtained by the following equation (6).

The magnitude of the outer product vector V _j × V _{j + 1} is expressed by the following equation (7). If this equation (7) is modified, the angle θ _j is expressed by the equation (8) using the inverse function of sin. Can be represented. For this reason, it is conceivable to obtain the absolute value of the angle θ _j from the outer product. However, in general, since the sin function is a function in which the relationship of sin θ _j = sin (π−θ _j ) is established, the absolute value of θ _j is uniquely determined by the equation (8) using the inverse function. I can't.

FIGS. 6A and 6B are flowcharts showing an example of the operation of the reflection path determination unit 22. First, a description will be given with reference to FIG. With respect to the reflection path obtained by the reflection path calculation unit 21, the three-dimensional coordinates of the reflection point P where the reflection path intersects the plane including the wall surface W are calculated (step S101). Next, a signed angle θ _j is calculated for each of adjacent vertices a _j and a _{j + 1} of the wall surface W (step S102). Then, the absolute value of the sum of all the angles θ _j is compared with a predetermined threshold θth. When the absolute value is smaller than the threshold θth, it is determined that the reflection path is invalid. Then, it is determined that the reflection path is valid (step S103). In the case of a secondary or higher-order reflection path, the same determination is repeated for each reflection point, and the reflection path is valid only when it is valid for all reflection points.

(B) in the figure is a diagram showing an example of processing for calculating the signed angle θ _j . First, the inner product of the vectors V _j and V _{j + 1} from the reflection point P to two adjacent vertices a _i and a _{i + 1} is obtained (step S201). Based on this inner product, the absolute value of the angle θ _j is obtained (step S202). That is, the absolute value of the angle θ _j is obtained according to the above-described equation (4).

Next, the outer product vector U _{j of} the vectors V _j and V _{j + 1} is obtained (step S203). Based on the inner product of the outer product vector U _j and the reference vector N, the sign of the angle θ _j is obtained (step S204). That is, the sign of the angle θ _j is obtained according to the above-described equation (6).

According to the present embodiment, when determining the effectiveness of the reflection path obtained by the virtual image method, the vector calculation using the three-dimensional coordinates of each vertex a _j , sound source S, and sound receiving point R that define the wall surface is performed. Is going. Therefore, the effectiveness of the reflection path can be determined by a relatively simple calculation process using the three-dimensional coordinates as they are. Therefore, for example, the amount of calculation can be reduced and the calculation of acoustic characteristics and the acoustic simulation can be executed at a higher speed than in the case where the determination is performed by performing coordinate transformation or the like.

  In the acoustic simulation apparatus according to the present embodiment, it is assumed that the wall surface W is a polygon. However, in some cases, a part or all of the boundary of an actual wall surface is a curved line. When such a wall surface exists, acoustic simulation can be performed for all wall surfaces by replacing the curved portion with one or more line segments and approximating the boundary to a polygon. For example, the approximation calculation is performed in advance, and the obtained polygonal wall surface data W may be stored in the wall surface data storage unit 11 in advance. As another method, when the data of the wall surface W having the curved portion is stored in the wall surface data storage unit 11 and the effectiveness of the reflection point P on the wall surface W is determined, the reflection path determination unit 22 is used. May perform approximate calculation.

In this embodiment, when determining the effectiveness of the reflection path, it is necessary to perform an arithmetic process including a trigonometric function (cos ⁻¹ , sin ⁻¹ ), but an approximate process is adopted for the arithmetic process. By doing so, it is possible to shorten the calculation time while suppressing the cost for the calculation process. For example, it is possible to determine the effectiveness of the reflection path by employing an approximate expression for the calculation of the trigonometric function or by referring to the data table of the trigonometric function.

Embodiment 2. FIG.
FIG. 7 is an explanatory diagram showing a case where the reflection point P exists at a specific position on the wall surface W. FIG. (A) in the figure is when the reflection point P is on the side of the wall surface W, (b) is on the extension line of the side of the wall surface W, and (c) is on the vertex of the wall surface W. The case where it exists is shown.

In any of the cases (a) to (c), since the two adjacent vertices a _j and a _{j + 1} and the reflection point P are arranged on one straight line, the outer product V _j × V _{j + 1} becomes 0. In some cases, the outer product never becomes zero. On the other hand, the inner product V _j · V _{j + 1} is a negative value in the case of (a), a positive value in the case of (b), and 0 in the case of (c). Therefore, when the outer product and inner product are obtained, it is determined that the reflection point P exists on the target side, on the extension of the target side, or on one target vertex. be able to.

  Even if it is found that the reflection point P exists on the extension of the side of interest, it cannot be immediately determined whether the reflection point P is inside the wall surface W or not. On the other hand, if it is found that the reflection point P exists on the side or the vertex, it can be immediately determined whether or not the reflection point P exists in the wall surface W. That is, when the reflection point P exists on the side or the vertex, there are a method for determining that the reflection path is valid and a method for determining that the reflection path is invalid. At the time of determination, the effectiveness of the reflection path can be determined. Therefore, it is possible to omit a calculation process to be performed thereafter for determining the effectiveness of the reflecting surface.

FIG. 8 is a diagram illustrating an example of a calculation process of the signed angle θ _j according to the second embodiment of the present invention. First, the inner product and outer product of vectors V _j and V _{j + 1} are obtained (steps S301 and S302). As a result, if the outer product is not 0, the process proceeds to step S305, and the absolute value and sign of the angle θj are obtained (steps S305 and S306). That is, if the reflection point P does not exist at a unique position, the processing is exactly the same as in the case of FIG.

  Even if the outer product is 0, if the inner product is positive, the process proceeds to step S305 (step S304). That is, if the reflection point P exists on the extension of the side of interest, the processing is exactly the same as in the case of FIG.

On the other hand, if the outer product is 0 and the inner product is 0 or negative, the discrimination process is terminated (step S304). Since it can be determined that the reflection point P is on the target side or one of the target vertices, the determination process is terminated without calculating the signed angle θ _j . In consideration of calculation errors, even if the outer product is not 0, if the absolute value is less than an arbitrary small value ε, the value can be regarded as 0 and the above determination can be made. That is, an outer product that satisfies the following equation using ε may be regarded as 0.

  According to the present embodiment, when the reflection point P exists on the side or apex of the wall surface W, the effectiveness of the reflection path can be determined based on the calculation results of the inner product and outer product. Accordingly, it is possible to further reduce the amount of calculation for determining the effectiveness of the reflecting surface.

Embodiment 3 FIG.
In the first and second embodiments, the case has been described in which it is determined whether or not the reflection point P obtained by the virtual image method exists in the wall surface W, and whether or not the reflection path is valid. In the present embodiment, it is further determined whether or not there is another wall surface W blocking the path on the reflection path obtained by the virtual image method, and it is determined whether or not the reflection path is valid. The case will be described.

  FIG. 9 is a functional block diagram showing a configuration example of an acoustic simulation apparatus according to Embodiment 3 of the present invention. Compared to the acoustic simulation apparatus of FIG. 1 (Embodiment 1), it differs in that it includes a reflection path determination unit 22 ′ including a first determination unit 22 a and a second determination unit 22 b.

  The first determination unit 22a corresponds to the reflection path determination unit 22 in FIG. That is, as described in detail in the first and second embodiments, the first determination unit 22a determines whether or not the reflection point P exists in the wall surface W, and determines whether or not the reflection point P is valid. Deciding. On the other hand, the second determination unit 22b determines whether or not there is another wall surface W (a wall surface not including the reflection point P) on the reflection path obtained by the reflection path calculation unit 21, It is determined whether or not the reflection path is valid.

  In the virtual image method, the reflection path Q is derived by obtaining the virtual images S ′ and S ″ of the sound source S for an arbitrary wall surface, so that a sound ray is placed on the reflection path Q obtained by the reflection path calculation unit 21. It is not considered whether there are obstacles that obstruct. For this reason, even if the first determination unit 22a determines that the reflection path Q is effective, the reflection path Q is not always an effective path. That is, when the first determination unit 22a determines that any of the reflection points P constituting the reflection path Q is invalid, it can be determined that the reflection path Q is an invalid path. If it is determined that the reflection point P is valid, the path becomes an effective path if no other wall surface W exists on the reflection path Q, and the path becomes invalid if another wall surface W exists.

FIG. 10 is a diagram showing an example in the case where an obstacle exists on the reflection path obtained by the virtual image method. The sound source S, the sound receiving point R and the wall surface W ₁ to _W-4, if it is arranged as shown in FIG. 4, the reflection path obtained by the image source method becomes Q2 to Q4. Reflection path Q2, Q3 are the primary reflection path about the wall W1, W4 respectively, reflected path Q4 is a secondary reflection path about the wall surface _{W 1} and _{W 4.} In the first determination portion 22a, all of the reflection point for any reflection path Q2~Q4 is determined to be valid, in practice, the reflected path Q4 is blocked by the protruding portion made of walls W ₂ and W ₃ Therefore, not the effective route but only the reflection routes Q2 and Q3 are effective routes.

  With respect to such a sound field, a case where an acoustic simulation is performed using the acoustic simulation apparatus of FIG. 9 will be described. Since all the reflection paths Q2 to Q4 in FIG. 10 have reflection points on the wall surface, the first determination unit 22a determines that all reflection points are valid. The second determination unit 22b determines whether there is a wall surface other than the wall surface related to the derivation of the reflection path on the reflection paths Q2 to Q4 determined to be effective by the first determination unit 22a. It is determined whether the route is a simple route.

That is, it is determined whether or not the reflection path Q2 intersects the wall surfaces W _{2 to} W ₄ . Similarly, it is determined whether the reflection path Q3 intersects with the wall surfaces W _{1 to} W _3, and the reflection path Q4 is determined whether it intersects with the wall surfaces W ₂ , W ₃ . As a result, the reflected path Q4, while being determined to be invalid because it intersects with the wall surface W ₂ and W _3, the reflected path Q2 and Q3 to not intersect, is determined to be valid.

  In order to determine whether or not the reflection path Q intersects a wall surface W that does not have the reflection point, first, the second determination unit 22b first includes a plane including the wall surface W other than the wall surface related to the derivation of the reflection path Q (infinite The intersection point T that intersects the plane of This intersection T will be referred to as a cutoff point. When such a blocking point T exists and is located in the wall surface W, the reflection path Q can be determined to be invalid, and otherwise, it can be determined to be valid. .

The determination process for determining whether or not the blocking point T exists in the wall surface W uses the same method as the determination process for determining whether or not the reflection point P exists in the wall surface W in the first and second embodiments. can do. That is, at a cutoff point T where the reflection path Q intersects a plane including the wall surface W, a signed angle θ _j formed by two adjacent vertices a _j and a _{j + 1 of the} wall surface W is obtained, and the cutoff point is determined based on the sum of the angles. Whether or not T exists on the wall surface W can be determined.

At that time, the absolute value of the signed angle θ _j is obtained from the inner product of the vectors V _j and V _{j + 1} connecting the two adjacent vertices a _j and a _{j + 1} and the cutoff point T, and the sign of the angle θ _j is It is obtained from the inner product of the outer product vector of the vectors V _j and V _{j + 1} and the reference vector (for example, the normal vector of the wall surface W) intersecting the wall surface W. Further, in the case of the first and second embodiments, these arithmetic processes can be performed using a trigonometric function based on the three-dimensional coordinates of each vertex a _j and the blocking point T that define the wall surface W. Is exactly the same.

FIG. 11 is a diagram illustrating a state of the determination process in the second determination unit 22b of FIG. (A) in the drawing shows the case of the reflection path Q2 in FIG. Reflection path Q2 consists path SP ₁ and path _{P 1} R, these routes _{P 1} R intersects the plane as blocking points _{T 1} including the wall W3. However, since this blocking point T1 does not exist in the wall surface W3, it can be determined that the reflection path Q2 is an effective path.

(B) in the figure shows the case of the reflection path Q4 in FIG. Reflection path Q4 includes a path SP _2, a path _P 2 _{P 3,} made from the path _{P 3} R, these are the path _P 2 _{P 3,} intersect at the wall surface W2, intercept point and a plane containing the W3 _T 2, _{T 3} is doing. Since these blocking points T ₂ and T ₃ exist in the wall surfaces W 2 and W 3, it is possible to determine that the reflection path Q 4 is an invalid path.

  According to the present embodiment, it is determined whether there is an obstacle that blocks the sound ray on the reflection path obtained by the virtual image method, thereby determining the reflection path that is invalidated by the presence of the obstacle. be able to. In addition, in the determination process, the same vector calculation as in the first and second embodiments is performed. Therefore, the effectiveness of the reflection path can be determined by a relatively simple calculation process using the three-dimensional coordinates as they are.

  In the present embodiment, an example in which it is determined whether or not there is a wall surface W that becomes an obstacle on the reflection path is described. It is possible to determine the presence of a wall surface as an object. For example, such a determination process can be employed in the direct route calculation unit 20.

It is the functional block diagram which showed the example of 1 structure of the acoustic simulation apparatus by Embodiment 1 of this invention. It is the figure which showed an example of the direct path | route and the reflection path | route. It is the figure which showed an example of the secondary reflection path | route. It is explanatory drawing which showed the basic principle for discriminating the effectiveness of a reflective path. It is explanatory drawing about the method of calculating _| requiring signed angle (theta) _j . 5 is a flowchart illustrating an example of an operation performed by a reflection path determination unit 22. 5 is an explanatory diagram showing a case where a reflection point P exists at a specific position on a wall surface W. FIG. It is the figure which showed an example of the calculation process of signed angle (theta) _j by Embodiment 2 of this invention. It is the functional block diagram which showed the example of 1 structure of the acoustic simulation apparatus by Embodiment 3 of this invention. It is the figure which showed an example in case an obstruction exists on the reflective path | route calculated | required by the virtual image method. It is the figure which showed the mode of the discrimination | determination process in the 2nd discrimination | determination part 22b of FIG. It is explanatory drawing which showed an example of the conventional method which calculates | requires a reflective path | route. It is the figure which showed an example of the reflective path | route calculated | required by the virtual image method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Acoustic characteristic calculation part 11 Wall surface data storage part 12 Listening sound production | generation part 20 Direct path | route calculation part 21 Reflection path | route calculation part 22 Reflection path | route discrimination | determination part 22a 1st discrimination | determination part 22b 2nd discrimination | determination part 23, 24 Propagation characteristic calculation part 25 Synthesis | combination part a1~a4 wall vertices of N reference vectors _{P, P} 1 ~P ₃ reflection point Q1 direct path Q2~Q4 reflection path S source _R, R 1, _{R 2} sound receiving point _{T, T} 1 ~T ₃ cutoff point _{U j} outer product Vector V _j , V _j vector W, W _{1 to} W ₃ Wall surface θ _j Signed angle θth threshold value formed by adjacent vertex at reflection point

Claims (12)

An operation method of an acoustic reflection path discriminating apparatus, wherein the effectiveness of a reflection path obtained by a virtual image method is discriminated based on the coordinates of each vertex that defines a polygonal reflecting surface piece. ,
Based on the order of the vertices that appear when the outer periphery of the reflecting surface piece is traced in one direction, a sign is formed by two adjacent vertices at a reflecting point where the reflecting path intersects the plane including the reflecting surface piece. An angle calculating step for obtaining an angle;
An angle integration step for obtaining the sum of the signed angles obtained for all adjacent vertices;
An acoustic reflection path discrimination method comprising: a first discrimination step for discriminating whether or not the reflection point exists on the reflection surface piece based on the sum of the signed angles. The angle calculating step
A first inner product calculating step for obtaining an inner product of vectors connecting two adjacent vertices and the reflection point;
Obtaining an absolute value of the angle based on the inner product obtained in the first inner product calculating step;
An outer product calculation step for obtaining an outer product vector of vectors connecting the adjacent vertex and the reflection point;
The acoustic product according to claim 1, further comprising: a second inner product calculation step of calculating an inner product of the outer product vector obtained in the outer product calculation step and a reference vector intersecting the reflecting surface piece and obtaining a sign of the angle. Reflection path discrimination method.   The acoustic reflection path determination method according to claim 2, wherein the reference vector is a normal vector of the reflecting surface piece.   The first determination step determines whether the reflection point exists on the reflection surface piece by comparing the absolute value of the sum of the signed angles with a positive threshold value smaller than 2π. The acoustic reflection path discriminating method according to claim 1, wherein the acoustic reflection path is discriminating.   5. The acoustic reflection path according to claim 1, further comprising a second determination step of determining whether or not a reflection surface piece that does not include the reflection point exists on the reflection path. How to determine. A program for discriminating an acoustic reflection path for determining the effectiveness of a reflection path obtained by a virtual image method based on the coordinates of each vertex defining a polygonal reflecting surface piece,
Based on the order of the vertices that appear when the outer periphery of the reflecting surface piece is traced in one direction, the two adjacent reflecting surface pieces at the reflecting point where the reflecting path intersects the plane including the reflecting surface piece. An angle calculating step for obtaining a signed angle formed by the vertices;
An angle integration step for obtaining the sum of the signed angles obtained for all adjacent vertices;
A program comprising a procedure for causing a computer to execute a first determination step of determining whether or not the reflection point exists on the reflection surface piece based on the sum of the signed angles. The angle calculating step
A first inner product calculating step for obtaining an inner product of vectors connecting two adjacent vertices and the reflection point;
Obtaining an absolute value of an angle formed by the adjacent vertex at the reflection point based on the inner product obtained in the first inner product calculation step;
An outer product calculation step for obtaining an outer product vector of vectors connecting the adjacent vertex and the reflection point;
7. The program according to claim 6, further comprising: a second inner product calculating step for obtaining an inner product of the outer product vector obtained in the outer product calculating step and a reference vector intersecting the reflecting surface piece, and obtaining a sign of the angle. . 8. The method according to claim 6, further comprising: causing a computer to execute a second determination step of determining whether or not there is a reflecting surface piece that does not include the reflection point on the reflection path. Program . In the acoustic reflection path discriminating apparatus for discriminating the effectiveness of the reflection path obtained by the virtual image method, based on the coordinates of each vertex defining the polygonal reflecting surface piece,
Based on the order of the vertices that appear when the outer periphery of the reflecting surface piece is traced in one direction, the two adjacent reflecting surface pieces at the reflecting point where the reflecting path intersects the plane including the reflecting surface piece. An angle calculating means for obtaining a signed angle formed by the vertex;
Angle integration means for calculating the sum of the signed angles determined for all adjacent vertices;
An acoustic reflection path discriminating apparatus comprising: a first discriminating unit that discriminates whether or not the reflection point is present on the reflection surface piece based on the sum of the signed angles.   The acoustic reflection path determination device according to claim 9, further comprising second determination means for determining whether or not a reflection surface piece that does not include the reflection point exists on the reflection path. Based on the coordinates of each vertex that defines the polygonal reflecting surface piece, the reflection point calculation that obtains the coordinates of the reflecting point where the reflection path obtained by the virtual image method intersects the plane including the reflecting surface piece related to the derivation Means,
First inner product calculation means for obtaining an inner product of vectors connecting two adjacent vertices of the reflecting surface piece and the reflecting point;
Absolute value calculating means for obtaining an absolute value of an angle formed by the adjacent vertexes at the reflection point based on the inner product obtained by the first inner product calculating means ;
Based on the order of the vertices that appear when the outer periphery of the reflective surface piece is traced in one direction, an outer product calculation means for obtaining an outer product vector of vectors connecting the adjacent vertices and the reflection points;
A second inner product computing means for obtaining an inner product of the outer product vector obtained by the outer product computing means and a reference vector intersecting the reflecting surface piece, and obtaining a sign of the angle;
First discriminating means for discriminating whether or not the reflection point is present on the reflecting surface piece based on the sum of the signed angles;
Propagation characteristic calculation means for obtaining a propagation characteristic of a reflection path from the sound source to the sound receiving point by the reflection surface piece based on the determination result in the first determination means;
An acoustic simulation apparatus comprising: listening sound generation means for generating a listening sound at a sound receiving point from an output sound of a sound source using propagation characteristics of a reflection path. A second discriminating means for judging whether or not the reflection path intersects with a reflection surface piece not including the reflection point;
12. The propagation characteristic calculating means obtains a propagation characteristic of a reflection path from a sound source to a sound receiving point by the reflecting surface piece based on the discrimination results in the first and second discrimination means. Acoustic simulation device.

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