JP2003105893A - Indoor acoustic designing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an indoor acoustic designing method which efficiently carries out indoor acoustic design. SOLUTION: According to the method, a relational expression is prepared by setting an articulation index, a value of (room volume/room surface area), and a mean sound absorbing coefficient α as parameters, beforehand. Then, the value of the (room volume V/room surface area S) of a target room, and the mean sound absorbing coefficient α corresponding to a desired value of the articulation index STI, is determined based on the relational expression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for designing room acoustics of a building. Further, the present invention relates to an acoustic design method for a room which is effective for planning measures for repairing a room with poor clarity.

[0002]

2. Description of the Related Art In the prior art, a method of predicting the average intelligibility of a room at the stage where all other conditions are determined, rather than determining the average sound absorption coefficient of the room from the target intelligibility Met.

[0003]

In the above-mentioned prior art, the method of approaching the predicted intelligibility to the design target value (target intelligibility) while giving the average sound absorption coefficient and reverberation time by trial and error is inevitable. It takes a lot of work because you don't get it. In addition, since the prediction calculation must be performed with the sound source and the sound receiving point fixed, the calculation is performed at a considerable number of points when obtaining the average intelligibility in the room. Therefore, there is a problem that it takes a lot of time to determine the average sound absorption coefficient and the reverberation time.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a room acoustic design method capable of efficiently performing room acoustic design.

[0005]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention uses intelligibility, (chamber volume / chamber surface area), and average sound absorption coefficient as parameters in advance. Providing a relational expression, and based on the relational expression, provide an acoustic design method for the room, characterized by obtaining the average sound absorption coefficient corresponding to the (room volume / room surface area) and the target intelligibility of the target room To do.

Next, the invention according to claim 2 prepares a relational expression in which the intelligibility, (room volume / room surface area), and average sound absorption coefficient are parameters in advance, and the intelligibility, ( Map data representing the relationship between the room volume / room surface area) and the average sound absorption coefficient is made into a database, and based on the database, the average corresponding to the (room volume / room surface area) and the target intelligibility of the target room. An acoustic design method for a room, which is characterized by obtaining a sound absorption coefficient.

Next, the invention described in claim 3 is characterized in that, in addition to the structure described in claim 1 or 2, an interior material satisfying the above-obtained average sound absorption coefficient is selected. is there. Next, the invention according to claim 4 prepares a relational expression in which clarity, (room volume / chamber surface area), and average sound absorption coefficient are parameters in advance, and based on the relational expression, clarity and average sound absorption coefficient And a clearness-average sound absorption coefficient curve are obtained by changing the (room volume / room surface area) of the room to obtain a chart, and acoustic design is performed based on the chart. An acoustic design method is provided.

Next, the invention described in claim 5 prepares a relational expression with parameters of clarity, (room volume / chamber surface area), and reverberation time in advance, and based on the relational expression, the target room (Room volume / Room surface area) and Reverberation time corresponding to target intelligibility are provided. Next, in the invention described in claim 6, a relational expression having parameters of clarity, (room volume / chamber surface area), and reverberation time is prepared in advance. The map data representing the relationship between the surface area) and the reverberation time is stored in a database, and the reverberation time corresponding to the (room volume / room surface area) and the target intelligibility of the target room is calculated based on the database. The present invention provides a characteristic room acoustic design method.

Next, the invention described in claim 7 is characterized in that, in addition to the structure described in claim 5 or 6, an interior material satisfying the above-mentioned reverberation time is selected. . Next, the invention according to claim 8 prepares a relational expression in which the intelligibility, (room volume / room surface area), and reverberation time are parameters in advance, and based on the relational expression, the intelligibility and the reverberation time are defined. Clarity-reverberation time curve
The present invention is characterized in that a plurality of charts drawn by changing the room surface area) are obtained, and acoustic design is performed based on the charts.

In the present invention, the relation between the intelligibility and the average sound absorption coefficient or the reverberation time is theoretically related by a simple relational expression, and based on the relation, the average sound absorption rate or the reverberation time for setting the target intelligibility. By simply requesting
The acoustic design of the room can be efficiently performed. That is, from the intelligibility set as a design target when designing room acoustics (an index related to the transmission performance of voice that indicates that the higher the number, the more clearly the voice can be heard), the room acoustics considered to be the most suitable for clearing the target at the time of completion. The average sound absorption coefficient or reverberation time, which is one of the design indexes, can be determined easily and accurately from the chamber volume and the chamber surface area.

At this time, according to the invention described in claim 3 or claim 7, the interior material is selected so as to obtain the obtained average sound absorption coefficient or reverberation time. The clarity can be set to. If the target average sound absorption rate or reverberation time cannot be achieved by selecting the interior materials, change the characteristics and position of the sound source (speaker) (change β described below), the volume / surface area of the room, and then By repeating the above process, the design is performed so as to obtain the desired intelligibility. In some cases, the target intelligibility is changed and the above process is repeated. It can be easily repeated in this way.

Further, according to the inventions according to claims 4 and 8, it is possible to easily obtain each of the charts described above, and the tendency of mutual influence of design variables can be seen at a glance by the charts. It enables efficient acoustic design. Here, each relational expression used in the above-mentioned invention will be described. As one of the existing intelligibility evaluation indexes using impulse response, there is SNR (Signal-to-Ratio) proposed by Lochner and Burger for evaluating initial reflection sound, residual reverberation sound, and background noise.

It is known that the calculation formula for this SNR is represented by the following formula (1).

[0014]

[Equation 1]

Here, p (t): instantaneous sound pressure p _N : steady background noise α (p, t): coefficient that changes depending on sound pressure and arrival time T: duration Δt: effective initial reflected sound It represents the maximum delay time from the direct arrival time.

If this equation (1) is converted into an evaluation amount that can be calculated by a method based on the statistical room acoustic theory, it can be defined by the following equation (2).

[0017]

[Equation 2]

In this equation (2), E _d is the energy density of the direct sound, E _e is the energy density of the initial reflected sound, and the sum of these corresponds to the integral of the numerator of equation (1). E _r E _BGN is the energy density of the residual reverberation and the background noise, respectively, and corresponds to the denominator of equation (1). Each energy density is calculated by the following formula.

[0019]

[Equation 3]

Here, W is the sound power of the sound source, and if the power level is PWL,

[0021]

[Equation 4]

Is given by Further, c is the speed of sound, Q is the directivity coefficient of the sound source, r is the average distance from the sound source to the listening position, R is the room constant (= Sα / (1-α)), and α is the average sound absorption coefficient. The directivity coefficient Q is given by the following equation by the directivity characteristic D (θ, φ) of the sound source itself and the radiation solid angle Ω determined by the place where the sound source is installed.

[0023]

[Equation 5]

Further, n is the reflection order of the reflected sound that contributes to clarity, and the mean free path p = 4 (V / S) (V: volume,
By S: surface area, it is expressed as n = (r + cΔt) / p. If the background noise can be ignored, the SNR _stat is expressed by the following equation.

[0025]

[Equation 6]

Further, when the direct sound component in the above equation is replaced by the product of the spatial average energy density using the mean free path and the direct sound enhancement coefficient β, and considering the influence of air absorption, it is expressed by the following equation. It

[0027]

[Equation 7]

Here, the direct sound enhancement coefficient β indicates how much the average direct sound energy density is enhanced by the directivity of the sound source, the distance to the sound receiving point, the use of a plurality of speakers, and the like. Β = (D · r / p) (D: directional characteristic, r: average distance from sound source to listener, p:
Average free path). Further, m is the attenuation rate per meter.

This equation is a basic feature of a building (V /
If S) and β, which is the feature of the sound source, are determined, SNR _stat indicating the intelligibility can be expressed as being related to the average sound absorption coefficient α. Further, the inventors confirmed from the results of the hearing experiment under the same conditions that the SNR _stat and the STI have a certain correlation, as shown in FIG. 7.

The straight line in the figure is a regression line, and SNR _stat =
34.0 x STI-14.8. The correlation coefficient is 0.88, and it can be seen that SNR _stat and STI have a certain correlation. Transforming the above equation, STI =
(SNR _stat +14.8) /34.0, and when the above equation (10) is substituted into this equation, the following equation (11) is obtained.

[0031]

[Equation 8]

This relational expression is an existing index S that expresses intelligibility.
TI (Speech Transmission In)
dex), average sound absorption rate α, (V / S) (value obtained by dividing volume by surface area), sound velocity c, effective reflected sound arrival time Δt, attenuation rate m due to air absorption, and direct sound enhancement coefficient β. ,
If the sound velocity c, the effective reflection sound arrival time Δt, the attenuation rate m due to air absorption, and the direct sound enhancement coefficient β are determined, the intelligibility index ST
It is a relational expression with I, the average sound absorption coefficient α, and (V / S) as parameters.

That is, by preparing the above relational expression in advance and setting (V / S) obtained from the design target STI and the basic shape of the room, the average sound absorption coefficient is easily determined. Regarding the reverberation time T, by applying the following Eyring-Knudsen equation (12) to the equation (11), the intelligibility index STI (SpeakechTra) can be obtained.
nsmission Index) Reverberation time T, (V /
The relational expression has S) as a parameter.

[0034]

[Equation 9]

Here, K is a value obtained by dividing 55.26 by the speed of sound. Note that the clarity index STI, reverberation time T, (V
The relational expression using / S) as a parameter is not a single equation but is composed of the above two relational expressions, that is, it is obtained by once obtaining the average sound absorption coefficient and converting the average sound absorption coefficient into the reverberation time T. You may do it.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a first embodiment of the present invention will be described with reference to the drawings. In this embodiment, first,
The relational expression of the above formula (11) is prepared. Then, the processing is performed according to the processing flow shown in FIG. 1 to obtain the average sound absorption coefficient α, and the interior material of the target room is selected so as to have the obtained average sound absorption coefficient α.

First, in step S10, the effective reflected sound arrival time Δt is set and input. Arrival time of effective reflected sound Δt
According to the research conducted so far, the value of is usually 0.05 to 0.10 (seconds), which is the most stringent value. adopt. Also in this embodiment, 0.05 second is set. Next, in step S20, the attenuation rate m due to air absorption is set. This value depends on the ISO
It may be selected based on 9313-1.

For example, when the temperature is 20 ° C. and the humidity is 50%,
If 500 Hz, m = 0.000, but 2000
If the sound in the Hz band is important, the air absorption cannot be ignored, so that about m = 0.003 is given.
In this embodiment, m = 0.00. Next, step S
At 30, the direct sound enhancement coefficient β is set. Normally β = 1
However, if the directivity of the sound source and the average distance from the sound source to the listener are taken into consideration, the value of β should be 1
Set larger.

Next, in step S40, a chart consisting of the average sound absorption coefficient α-STI curve group is extracted while changing (V / S) stepwise. FIG. 2 is the extracted chart diagram. In FIG. 2, “IEC SCALE” shown below the numerical value on the horizontal axis is an evaluation word defined by the International Electrotechnical Commission. FIG. 3 is an example of a chart diagram when setting variables are different.

Next, in step S50, the STI which is the design target is set, and in step S60, (V / S) is selected and input from the basic shape of the target chamber.
Next, in step S70, the average sound absorption coefficient α is calculated directly from the chart diagram or the relational expression. Next, in step S80, an interior material that can have the calculated average sound absorption coefficient α is selected.

Further, in step 90, it is judged whether or not the interior can satisfy the determined average sound absorption coefficient α, and if it is impossible, at least β, STI which is a design target, and (V / S) are determined. One change is urged, and if any of the values is changed, the average sound absorption coefficient α is obtained again based on the relational expression, and it is determined whether the interior that satisfies the average sound absorption coefficient α is possible.
The above processing is repeated until the interior that satisfies the average sound absorption coefficient α becomes possible.

Here, since "Σ (sound absorption rate of each part x surface area of that part) / total surface area" of the room is the average sound absorption rate α, the interior used for each part (ceiling, wall, etc.) The target average sound absorbing material α is obtained by appropriately selecting the material. Also,
When using the above chart, draw (V /
The value of S) or the interval thereof may be set in advance, and the system may be configured so that the computer automatically draws the chart diagram based on the input value. That is, it is preferable to include an automatic drawing means for automatically drawing the chart diagram based on the relational expression and the input or set (V / S).

Then, the processing may be repeated until the average sound absorption coefficient α that provides a possible interior is obtained based on the drawn chart diagram. Further, when STI and (V / S) are directly substituted into the functional expression to obtain the average sound absorption coefficient α, for example, each setting value is substituted on the menu screen for substituting the setting value, The system may be configured to calculate the average sound absorption coefficient α at.

Regarding the selection of the interior material and whether or not the interior is applicable, a system may be constructed in which applicable interior materials are registered in advance in the database and the computer automatically selects and determines the availability. . In the present embodiment, the average sound absorption coefficient α in the room, which is necessary for satisfying the design target intelligibility in a short time, is calculated based on one relational expression without performing complicated numerical calculation such as simulation. Can be calculated.

Furthermore, by selecting an interior having an average sound absorption coefficient α in the room that satisfies the design target intelligibility, it is possible to ensure that the target room has the intelligibility as the design target. Further, even when there is no interior that enables the calculated average sound absorption coefficient α, it is possible to easily obtain a new average sound absorption coefficient α by changing the setting conditions.

Further, when a chart is used, the tendency of mutual influence of design variables can be seen at a glance, so that efficient acoustic design is possible. Here, in the above-described embodiment, the case where the average sound absorption coefficient α is directly output or the above chart diagram is output by using a functional expression at the time of acoustic design is described. Not limited to. A system may be constructed in which a data map corresponding to the above chart is stored in a database in advance, and design variables are input to obtain the average sound absorption coefficient α from the data map in the database. At this time, for a set value that does not exist in the database, an approximate value thereof may be calculated and the average sound absorption coefficient α may be output.

Next, a second embodiment will be described with reference to the drawings. The basic configuration of this embodiment is the same as that of the first embodiment, except that the reverberation time T is calculated instead of the average sound absorption coefficient α. That is, as shown in the processing flow in FIG. 4, the basic configuration of the processing procedure is the same as that in the first embodiment (see FIG. 1).

However, as the relational expression, the relational expression (equation (11)) used in the first embodiment is converted into the reverberation time T based on the expression (12). Of course, the system may be constructed so that the average sound absorption coefficient α is once calculated by the above relational expression (Expression (11)) and the average sound absorption coefficient α is converted into the reverberation time T based on the expression (12). FIG. 5 shows a chart according to the present embodiment. In addition, FIG.
Shows the chart when the setting variables are changed.

Even in this embodiment, the numerical calculation such as the complicated and time-consuming simulation is not required.
Based on one or two relational expressions, it is possible to calculate the reverberation time T in the room that is necessary to satisfy the design target intelligibility in a short time. Furthermore, by selecting the interior that has the reverberation time T in the room that satisfies the intelligibility as the design target, it is possible to ensure that the target room has the intelligibility as the design target.

Even if there is no interior that enables the calculated reverberation time T, a new reverberation time T can be easily obtained by changing the setting conditions. Further, when the chart is used, the tendency of mutual influence of design variables can be seen at a glance, which enables efficient acoustic design.

[0051]

As described above, according to the present invention, general-purpose spreadsheet software for a personal computer can be used without giving detailed data to a large-scale computer and performing analysis by trial and error. As a result of being able to determine the average sound absorption coefficient and reverberation time corresponding to the intelligibility of the design target in a short time and in a short time, there is an effect that an efficient acoustic design can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a processing flow according to a first embodiment of the present invention.

FIG. 2 is an α-STI according to the first embodiment of the present invention.
It is a figure which shows the chart figure of a curve.

FIG. 3 is an α-STI according to the first embodiment of the present invention.
It is a figure which shows another chart figure of a curve.

FIG. 4 is a diagram showing a processing flow according to a second embodiment of the present invention.

FIG. 5 is a T-STI according to the first embodiment of the present invention.
It is a figure which shows the chart figure of a curve.

FIG. 6 is a T-STI according to the first embodiment of the present invention.
It is a figure which shows another chart figure of a curve.

FIG. 7 is a diagram showing a relationship between STI and SNR _stat .

[Explanation of symbols]

α Average sound absorption T reverberation time

Claims (8)

[Claims] 1. A relational expression using intelligibility, (chamber volume / chamber surface area), and average sound absorption coefficient as parameters is prepared in advance, and based on the relational expression, (chamber volume / chamber surface area) of the target chamber is prepared.
And a method of acoustic design in a room, characterized by obtaining an average sound absorption coefficient corresponding to a target intelligibility. 2. A relational expression having parameters of clarity, (room volume / chamber surface area), and average sound absorption coefficient is prepared in advance, and the clarity, (chamber volume / chamber surface area), and average sound absorption can be obtained by the relational expression. A room characterized in that map data representing the relationship of the rates is stored in a database, and the average sound absorption coefficient corresponding to the (room volume / room surface area) of the target room and the target intelligibility is obtained based on the database. Acoustic design method. 3. The room acoustic design method according to claim 1, wherein an interior material that satisfies the obtained average sound absorption coefficient is selected. 4. A relational expression using intelligibility, (room volume / chamber surface area), and average sound absorption coefficient as parameters is prepared in advance, and based on the relational expression, intelligibility and average sound absorption coefficient of clarity-average sound absorption An acoustic design method for a room, characterized in that a plurality of rate curves are drawn by changing (room volume / room surface area) of the room to obtain a chart, and acoustic design is performed based on the chart. 5. A relational expression having parameters of clarity, (chamber volume / chamber surface area), and reverberation time is prepared in advance, and based on the relational expression (chamber volume / chamber surface area) and target An acoustic design method for a room, characterized in that a reverberation time corresponding to the intelligibility is obtained. 6. A relational expression using intelligibility, (room volume / chamber surface area), and reverberation time as parameters is prepared in advance, and the relational expression of the intelligibility, (chamber volume / chamber surface area), and reverberation time is prepared by the relational expression. An acoustic design of a room characterized in that map data representing the relationship is made into a database, and the reverberation time corresponding to the (room volume / room surface area) and the target intelligibility of the target room is obtained based on the database. Method. 7. The room acoustic design method according to claim 5, wherein an interior material satisfying the calculated reverberation time is selected. 8. A relational expression having intelligibility, (room volume / chamber surface area), and reverberation time as parameters is prepared in advance, and an intelligibility-reverberation time curve between the intelligibility and reverberation time is calculated based on the relational expression. A method for acoustic design in a room, characterized in that a plurality of charts are drawn by changing (chamber volume / chamber surface area) of a room, and acoustic design is performed based on the chart.