Indoor space acoustic characteristics evaluation device, indoor space acoustic characteristics evaluation method, and program

Abstract

To enable simple prediction of speech articulation in an indoor spaces with higher accuracy without requiring specialized skills and knowledge of acoustics.SOLUTION: An indoor space acoustic characteristic evaluation device 1 includes a processing unit 11 for calculating speech articulation about an indoor space, wherein the processing unit 11 obtains predetermined attribute information about a target indoor space that is a target of STI calculation, calculates a delay time τ of reverberation sound at a sound receiving point in the target indoor space based on the predetermined attribute information, and calculates and outputs the STI of the target indoor space based on a virtual impulse response in the target indoor space as a transmission system of sound waves in which the delay time τ of the reverberation sound is incorporated.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to an indoor space acoustic characteristics evaluation apparatus, an indoor space acoustic characteristics evaluation method, and a program. [Background technology]

[0002] Speech Transmission Index (STI) is widely used as an objective measure to evaluate speech intelligibility, which indicates the transmission quality of sound when sound is emitted in an architectural space. The method for calculating STI is described, for example, in Non-Patent Document 1. According to this document, STI is calculated from the result of measuring the modulation transfer function (MTF (Modulation Transfer Function), hereinafter also denoted as M(F)) that represents the modulation degree of the output signal at the receiving point, by inputting the speech input signal emitted at the sound source location (modulation frequency F [Hz] with 100% amplitude modulation) into a transmission system composed of the space in which speech intelligibility is to be measured. The sound source input signal x(t) of the transmission system and the output signal y(t) at the receiving point are expressed as follows.

[0003]

number

[0004]

number

[0005] In the design phase of a building, predicting STI (Speech Integrity) in order to confirm speech intelligibility in the interior space requires first predicting MTF (Mean Time Shift), which in turn requires predicting the impulse response h(t). Simulation techniques for predicting impulse responses are already in practical use as commercially available, well-known indoor acoustic simulation software. However, predicting STI using such existing indoor acoustic simulation software requires extremely advanced skills and knowledge of acoustics, making it difficult for architectural designers to perform alone and necessitating the cooperation of acoustics specialists.

[0006] In this regard, Non-Patent Document 1 proposes a simplified prediction method for directly predicting MTF and STI by using an energy model of a transmission system that assumes the sound pressure level of sound waves propagating from the sound source through the space is exponentially attenuated, without determining the impulse response of the target space. The parameters used in this simplified STI prediction method are those that can be set by the design engineer, such as the volume of the space, the surface area, and the average sound absorption coefficient of the sound-absorbing material, making it possible to design while evaluating speech intelligibility without having to entrust the work to an acoustics expert. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Architectural Institute of Japan (ed.), "Architectural Institute of Japan Environmental Standards: Evaluation Criteria for Voice Transmission Performance in Urban and Architectural Spaces and Commentary," November 2011, Architectural Institute of Japan. [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the simplified prediction method described in Non-Patent Document 1 does not take into account the "reverberation delay time" that is considered in the original STI prediction process based on impulse response. As a result, the STI prediction results using this conventional simplified prediction method tend to be higher than the original STI prediction results, and there is a problem in that it is difficult to ensure sufficient prediction accuracy when using STI as an indicator to predict speech intelligibility at the design stage.

[0010] One of the objectives of the present invention is to provide an indoor acoustic characteristics evaluation device, an indoor acoustic characteristics evaluation method, and a program that enable the prediction of speech intelligibility in an indoor space with higher accuracy and in a simple manner, without requiring specialized skills or knowledge related to acoustics. [Means for solving the problem]

[0011] An indoor space acoustic characteristics evaluation device according to one aspect of the present invention includes a processing unit for calculating speech intelligibility for an indoor space, the processing unit acquires predetermined attribute information relating to a target indoor space that is the subject of speech intelligibility calculation, calculates the delay time of reverberation at the receiving point in the target indoor space based on the predetermined attribute information, and calculates and outputs the speech intelligibility of the target indoor space based on a transmission system model that simulates the impulse response in the target indoor space as a sound wave transmission system incorporating the delay time of reverberation.

[0012] The delay time of the reverberation can be calculated based on the difference between the critical distance, which is the distance from the sound source to the point where the sound pressure levels of the direct and indirect sound propagating from the sound source are the same in the target room space, and the distance from the sound source to the receiving point.

[0013] The aforementioned transmission system model can be described as an energy model that assumes the sound pressure energy of sound waves propagating from a sound source is exponentially attenuated.

[0014] The attribute information of the target indoor space, which is the input information of the transmission system model, may include at least the volume, internal surface area, and average sound absorption rate of the target indoor space.

[0015] The processing unit may also perform level division on the calculated speech intelligibility into a plurality of levels classified based on the difficulty of listening at the sound reception point, and output and display the result.

[0016] According to another embodiment of the present invention, a computer acquires predetermined attribute information regarding a target indoor space that is the target of speech intelligibility calculation, calculates the reverberation delay time at a sound reception point in the target indoor space based on the predetermined attribute information, and calculates and outputs the speech intelligibility of the target indoor space based on a transmission system model that simulates the impulse response in the indoor space as a sound wave transmission system incorporating the reverberation delay time, thereby providing an indoor space acoustic characteristic evaluation method.

[0017] A program for causing a computer to execute the indoor space acoustic characteristic evaluation method is also included in the present invention.

Effects of the Invention

[0018] [[ID=IS]] According to the present invention, it is possible to simply predict the speech intelligibility in an indoor space with higher accuracy without requiring specialized techniques and knowledge related to acoustics.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram illustrating a voice transmission system model in a simple prediction method of speech intelligibility. [Figure 2] It is a block diagram showing a hardware configuration example of an indoor space acoustic characteristic evaluation device according to an embodiment of the present invention. [Figure 3] It is a block diagram illustrating the functions of an indoor space acoustic characteristic evaluation device according to an embodiment of the present invention. [Figure 4] ​ [Figure 5] This is a schematic diagram illustrating an example of an indoor space to be evaluated for its acoustic properties. [Figure 6] This is a schematic diagram showing an example of an input / output screen provided by the device of this embodiment. [Figure 7A] Figure 5 illustrates the STI prediction results for the space shown in the example, using existing indoor acoustic simulation software and conventional simplified prediction methods. [Figure 7B] Figure 5 illustrates the STI prediction results obtained using existing indoor acoustic simulation software and the simplified prediction method of this embodiment for the space shown in the example. [Modes for carrying out the invention]

[0020] The present invention will be described below with reference to the accompanying drawings, in accordance with its embodiments.

[0021] <Simplified Speech Intelligibility Prediction Method According to This Embodiment> First, a simplified voice intelligibility prediction method according to one embodiment of the present invention will be explained in comparison with the simplified prediction method described in Non-Patent Document 1. Figure 1 schematically shows a comparison between the energy model of a spatial voice transmission system using the simplified prediction method described in Non-Patent Document 1 and the energy model of a spatial voice transmission system using the simplified prediction method of this embodiment.

[0022] As shown in Figure 1, the conventional simplified prediction method described in Non-Patent Literature 1 expresses the direct sound reaching the receiving point from the sound source and the reverberation sound reaching the receiving point while reflecting off the inner surfaces of the room space using the following mathematical formulas. The direct sound is modeled as a delta function of time t. The reverberation sound is modeled to decrease exponentially from t=0, which is the time of sound production.

[0023] ·Direct sound:

number

[0024] • Reverberation:

number

[0025] Here, Q1 is a coefficient indicating the directivity of the sound source, r is the distance from the sound source to the receiving point, r c θ is defined as the critical distance at which the direct and indirect sounds have the same sound pressure level, and t is the reverberation time. The energy model of the speech transmission system assumed when predicting STI is expressed as the sum of the direct and reverberation sounds, as the virtual impulse response h(t) in equation (5).

[0026]

number

[0027] critical distance r c This is expressed by equation (6).

number

[0028] Here, R is the room constant, an index that indicates the sound absorption of the indoor space. R is expressed by equation (7), where S is the total area of ​​the interior walls of the indoor space and α is its average sound absorption coefficient. R = αS / (1-α)···(7)

[0029] As is evident from Figure 1, which schematically illustrates the virtual impulse response h(t) described above, conventional simplified STI prediction methods do not take into account the reverberation delay time τ. Therefore, the STI value tends to be higher compared to the STI calculated by prediction methods using the actual impulse response, and this tendency becomes more pronounced the closer the distance from the sound source.

[0030] In contrast, in this embodiment, the energy model representing the audio transmission system incorporates a reverberation delay time τ. The delay time τ is defined as the distance r from the sound source to the receiving point, and the critical distance rc Assuming the speed of sound in air is c0, it is expressed as follows. τ≒(r c -r) / c0 ··· (8)

[0031] At this time, the virtual impulse response h(t) in this embodiment is expressed as in equation (9).

[0032]

Equation

[0033] In the simple prediction method of STI in this embodiment, next, using the above virtual impulse response h(t), the MTF necessary for calculating STI is calculated. That is, by substituting the virtual impulse response h(t) of equation (9) into equation (4) in the original STI prediction method described in the background art, the MTF can be calculated as follows. The modulation frequency F is 0.63 to 12.5 Hz.

[0034]

Equation

[0035] Note that the delay time τ of the reverberant sound is such that when r c <r, that is, when the distance r from the sound source to the sound receiving point is greater than the critical distance r c is larger, τ = 0 is set.

[0036] Based on the MTF (M(F)) obtained above, STI is calculated. The process of calculating STI from MTF is described, for example, on pages 32 to 33 of Non-Patent Document 1. Just in case, the outline is as follows. First, from the virtual impulse response h(t), the MTF is calculated for a 98 - matrix consisting of 7 audio frequency bands from 125 Hz to 8 kHz and 14 modulation frequencies from 0.63 Hz to 12.5 Hz.

[0037] To account for the effect of auditory masking from adjacent octave bands on the low-frequency side, correction is performed for each level by considering the AMF (Auditory Masking Factor). Next, the calculated MTF is converted to an equivalent signal-to-noise ratio (SNR), and the TI, which indicates the contribution of the equivalent SNR to clarity, is converted to a value between 0 and 1 within the range of -15dB to +15dB. Then, the MTI, which is the average TI for each audio frequency band, is determined, and the STI is calculated using weighting coefficients and redundancy correction coefficients for each audio frequency band. The STI calculated in this way is shown in equation (11).

[0038]

number

[0039] As explained above, according to the simplified STI prediction method in this embodiment, the reverberation delay time τ is introduced into the calculation of MTF and STI based on the virtual impulse response h(t).

[0040] <Example of a configuration for an indoor space acoustic characteristics evaluation system> Next, the configuration of the indoor space acoustic characteristics evaluation device 1 for calculating the STI for the indoor space using the simplified prediction method in this embodiment described above will be explained. Figure 2 is a block diagram illustrating the hardware configuration of the indoor space acoustic characteristics evaluation device 1 in one embodiment of the present invention. For the sake of simplicity, the indoor space acoustic characteristics evaluation device 1 will be hereinafter referred to as "evaluation device 1". As shown in Figure 2, the evaluation device 1 in this embodiment comprises a processing unit 11, a main memory unit 12, an auxiliary memory unit 13, an input unit 14, an output unit 15, and a communication unit 16.

[0041] The evaluation device 1 can be implemented as a general-purpose computer in various forms, including desktop and portable types. Alternatively, a program to implement the functions of the evaluation device 1 may be implemented on a server computer connected to a network, and configured to be accessible from client computers via the network. The main function of the evaluation device 1 is to calculate and output the STI (Speech Intelligibility Index) for the room space being evaluated based on predetermined input data, in order to perform an evaluation of speech intelligibility.

[0042] The hardware elements of the evaluation device 1 illustrated in Figure 2 will now be described. The processing unit 11 is composed of a processor that performs various calculations and control processes necessary for the operation of the evaluation device 1. The processing unit 11 can also be referred to as a processor. The processors that make up the processing unit 11 include, for example, a CPU (Central Processing Unit), MPU (Micro Processing Unit), SoC (System on a Chip), DSP (Digital Signal Processor), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field-Programmable Gate Array), or combinations thereof. Furthermore, the processing unit 11 may also be a combination of these processors with hardware accelerators, etc.

[0043] The main memory unit 12 stores a program for the processing unit 11 to execute the simplified STI prediction method in this embodiment, and also functions as a work area that is temporarily used for various processing tasks. The main memory unit 12 is composed of, for example, non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory).

[0044] The auxiliary storage unit 13 provides a storage area for storing parameter data and other information necessary for program execution. It may also store the calculated STI data. The program for calculating STI may be stored in the auxiliary storage unit 13 and stored in the main memory unit 12 when the program is executed. The auxiliary storage unit 13 is composed of semiconductor memory or the like.

[0045] The input unit 14 consists of various input devices such as a keyboard, mouse, and touch panel, and accepts input data through user operation. The output unit 15 consists of output devices such as a display for displaying images and a printer for printing output, and outputs images, text, etc. The input unit 14 and output unit 15 can also be configured with microphones, speakers, etc. to enable input and output of audio data.

[0046] The communication unit 16 controls the communication that the evaluation device 1 performs with other external information processing devices via various communication networks such as a LAN (Local Area Network). The communication unit 16 is composed of, for example, network connection devices such as a SIM (Subscriber Identity Module) card or a network adapter, and wireless communication devices based on communication standards such as Wi-Fi (Wireless Fidelity). The evaluation device 1 may also be configured as a standalone device without using the communication unit 16.

[0047] <Functions of Evaluation Device 1> Next, the functions realized by the processing unit 11 of the evaluation device 1 will be described. Figure 3 is a block diagram illustrating the functions realized by the processing unit 11 of the evaluation device 1 in one embodiment of the present invention. The processing unit 11 in this embodiment includes an input data receiving unit 111, a virtual impulse response generation unit 112, an MTF calculation unit 113, an STI calculation unit 114, a calculation result output unit 115, an input control unit 116, and an output control unit 117. These functional units are realized, for example, as a program executed by the processing unit 11. The method of realizing as a program can take any form, but as an example, it can be easily realized by embedding the required mathematical formulas in spreadsheet software that runs on a suitable operating system (OS).

[0048] The input data receiving unit 111 has the function of receiving input data used by the program operating in the evaluation device 1 through the input unit 14. The data received by the input data receiving unit 111 is passed on to the virtual impulse response generation unit 112, the MTF calculation unit 113, and the STI calculation unit 114 for use.

[0049] The virtual impulse response generation unit 112 takes the directivity Q1 of the sound source, the directivity Q2 of the reverberation, the room constant R, the distance r from the sound source to the receiving point, the reverberation time T, the delay time τ of the reverberation, and the speed of sound in air c0 as input and calculates a virtual impulse response h(t) for a given time t. The time interval for calculating h(t) can be determined as appropriate.

[0050] The MTF calculation unit 113 has the function of calculating MTF(M(F)) based on the virtual impulse response h(t) generated by the virtual impulse response generation unit 112. Specifically, the MTF calculation unit 113 uses equation (10) to calculate the MTF for 14 modulation frequencies in the range of 0.63 to 12.5 Hz (0.63, 0.80, 1.0, 1.25, 1.6, 2.0, 2.5, 3.15, 4.0, 5.0, 6.3, 8.0, 10.0, 12.5 Hz).

[0051] The STI calculation unit 114 has the function of calculating the STI using the MTF calculated by the MTF calculation unit 113 for each modulation frequency F, in accordance with the process described in Non-Patent Document 1.

[0052] The calculation result output unit 115 has the function of outputting the STI calculated by the STI calculation unit 114 in correspondence with the distance from the sound source. The calculated STI value for the distance from the sound source to the receiving point can be displayed graphically as well as numerically. Furthermore, the calculation result output unit 115 enhances user convenience by outputting and displaying the data entered as calculation conditions along with the calculated STI value. An example of the input / output screen of the evaluation device 1 will be described later.

[0053] The input control unit 116 executes a process to accept operations on the input unit 14 by the user.

[0054] The output control unit 117 performs processing to display an image on the screen of the output unit 15, or processing to print the output result to the printer acting as the output unit 15. For example, the output control unit 117 performs processing to generate display data, etc., based on the output data generated by the calculation result output unit 115 and display it on the screen of the output unit 15.

[0055] <Data processing by evaluation device 1> Next, the STI calculation process by the evaluation device 1 of this embodiment will be described. Figure 4 shows a flowchart illustrating the data processing flow performed by the processing unit 11 of the evaluation device 1 of this embodiment. The STI calculation process in this embodiment is started by turning on the power to the computer that functions as the evaluation device 1 and starting the program that realizes the functions of the processing unit 11.

[0056] When the program is started, in step S11, the input data receiving unit 111 first receives the data entered by the user through the input unit 14 and transfers the received data to the virtual impulse response generation unit 112. Specifically, the input data receiving unit 111 receives the room volume (m³) of the indoor space to be evaluated for acoustic characteristics. 3) The room surface area (m), which is the sum of the areas of the interior walls 2 ) It receives the coefficient Q1 indicating the directivity of the sound source, the coefficient Q2 indicating the directivity of the reverberant sound, the average absorption coefficient for each octave band frequency regarding the inner surface of the indoor space, and the input signal intensity (dB) for each octave band frequency, and transfers them to the virtual impulse response generation unit 112. Here, the room volume and the room surface area are assumed in advance as a rectangular parallelepiped having a width W, a height H, and a depth D as exemplified in FIG. 5 for the indoor space to be evaluated. Alternatively, it may be configured to cause the virtual impulse response generation unit 112 to calculate by inputting the dimensions of the rectangular parallelepiped assuming the indoor space. Also, the average absorption coefficient of the indoor space is input for each octave band frequency, but the average absorption coefficient is stored in advance for typical materials and interior finishes constituting the inner surface of the indoor space, and the average absorption coefficient may be configured to be set by selecting the type of material and interior finish of the inner surface from the input unit 14. The input signal at the sound source inputs the sound pressure level of the voice signal intensity-modulated by 100% for each octave band frequency.

[0057] In step S12, the virtual impulse response generation unit 112 generates a virtual impulse response h(t) based on the data input in step S11. The coefficient Q1 indicating the directivity of the sound source and the coefficient Q2 indicating the directivity of the reverberant sound can be appropriately adjusted according to the assumption of the indoor space. For example, it has been found that by setting Q1 = 2 and Q2 = 3 as recommended values, the STI can be predicted well. The room constant R used for calculating the delay time τ and the critical distance r of the reverberant sound is calculated from the input data. c

[0058] Next, in step S13, the MTF is calculated based on the virtual impulse response obtained in step S12. The calculation of the MTF is executed by the above-mentioned equation (10) described for the simplified STI prediction method of the present embodiment.

[0059] Based on the MTF calculated in step S13, the STI calculation unit 114 calculates the STI in step S14. The calculation of the STI is performed by equation (11) above, which was described in the simplified STI prediction method of this embodiment.

[0060] In step S15, the calculation result output unit 115 outputs the STI calculated in step S14 through the output unit 15. Figure 6 shows an example of the input / output screen 60 of the STI calculation result obtained by the evaluation device 1 according to this embodiment. This output screen example also serves as the input screen, as described in relation to the input data reception step S11. A calculation condition input area 61 is provided in the upper left of the screen for inputting calculation conditions. Input data related to the room space to be evaluated includes room volume, room surface area, sound source, coefficient indicating the directivity of reverberation, average sound absorption coefficient of the room surface, and input signal at the sound source. The input screen for inputting calculation conditions may be displayed on the input unit 14 as a separate screen from the output screen.

[0061] The operation area 62 is provided with a calculation execution button for instructing the evaluation device 1 to perform the STI calculation process, and a clear button for clearing the obtained calculation results.

[0062] In the calculation result output area 63, the calculated STI value calculated using the input calculation condition data is output for the distance from the sound source to the receiving point, and a graph plotting the calculated STI value against the distance from the sound source to the receiving point is displayed. This allows the user of the evaluation device 1 to not only understand the STI of the room under evaluation based on the calculated numerical value, but also to intuitively grasp the change in STI according to the distance from the sound source through the graphical display.

[0063] In the example input / output screen shown in Figure 6, the STI calculation value is displayed along with the rank to which it belongs in terms of speech intelligibility defined using STI. The International Electrotechnical Commission (IEC) standard, IEC60268-16 "Sound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index," defines the above ranks as follows:

[0064] STI Rating Rank Display Pattern 0.75~1.0: Excellent 1 Shading 0.6~0.75: Good 2 Vertical stripes 0.45~0.6: Fair 3 (Upward sloping line) 0.3~0.45: Poor 4 (downward sloping line) 0~0.3: Bad - No pattern

[0065] If we associate the above STI ranks with speech intelligibility (the degree to which one perceives difficulty in hearing), it would look something like this:

[0066] STI Rank: Difficulty in hearing 0.75~1.0: 1 Do not feel 0.6~0.75: 2 Almost no sensation 0.45~0.6: 3 I sometimes feel it. 0.3~0.45: 4 I sometimes feel it. 0-0.3: - Feel

[0067] In the evaluation device 1 of this embodiment, the table of STI calculation values ​​indicates which of the above evaluation ranks each calculation value corresponds to by the display pattern of the cell. In this way, by referring to the results of the STI calculation values, the relationship between the distance from the sound source and the perceived difficulty of hearing can be grasped intuitively at a glance. This display of STI ranks is also reflected in the graph of the STI calculation values, and in the example in Figure 7, the lower limit of each rank is displayed on the graph. This facilitates an intuitive understanding of the STI ranks. Furthermore, for the convenience of the user of the evaluation device 1, if, for example, audio files containing sample sounds corresponding to each STI rank can be played from the input / output screen, the user can intuitively experience how each STI rank sounds, which is extremely convenient.

[0068] Returning to the STI calculation process flow in Figure 6, after the output of the calculation result in step S15, the series of steps for the acoustic characteristic evaluation process is completed. Note that the input data or output data on the input / output screen can be deleted by operating the clear button provided in the operation area 62 of the input / output screen 60 as exemplified in Figure 6.

[0069] <Acoustic characteristics evaluation results using evaluation device 1> Next, the calculation results of STI performed using the evaluation device 1 according to this embodiment will be described. Figure 7A shows a comparison between the STI calculated by a conventional simplified prediction method that does not consider the reverberation delay time τ and the STI calculated by a conventional method using impulse response. Figure 7B also shows a comparison between the STI calculated by the simplified prediction method of this embodiment that considers the reverberation delay time τ and the STI calculated by a conventional method using impulse response. As the conventional method using impulse response, "CATT-Acoustic® (trademark)" (hereinafter abbreviated as "CATT"), one of the indoor acoustic simulation software, was used. The indoor space targeted for STI calculation is the indoor space model exemplified in Figure 5, with W = approximately 19m, D = approximately 32m, H = approximately 9m, and room volume V = approximately 3910m 3, room surface area S=approx. 1860m 2 For example, a building such as a gymnasium was assumed. In Figures 7A and 7B, the curve connecting the black plots shows the STI calculated using the simplified prediction method, and the white circle plots show the STI calculated based on the impulse response without using the simplified prediction method. Referring to Figure 7A, the calculation results using the simplified prediction method are higher than the calculation results using CATT in the range up to 10m from the sound source, and this trend becomes more pronounced the closer to the sound source. This difference is clearly shown, for example, as the discrepancy in the calculated STI value when the distance from the sound source to the receiving point is 1m. On the other hand, referring to Figure 7B, the calculation results using the simplified prediction method considering the delay time τ in this embodiment are closer to the calculation results using CATT than in the case of Figure 7A, indicating that a good result has been obtained.

[0070] As described above, the indoor space acoustic characteristics evaluation device 1 according to this embodiment includes a processing unit 11 for calculating the STI for the indoor space to be evaluated. The processing unit 11 acquires predetermined attribute information for the target indoor space to be used for STI calculation, calculates the reverberation delay time τ at the receiving point in the target indoor space based on this information, and calculates and outputs the modulation transfer function MTF and the STI, which is a measure of speech intelligibility, for the target indoor space based on a virtual impulse response in which the reverberation delay time τ is incorporated in the target indoor space as a sound wave transmission system.

[0071] In this way, even in a simple STI prediction method using a virtual impulse response that does not require specialized acoustic skills or knowledge, it is possible to appropriately incorporate the reverberation delay time and calculate the STI, thereby calculating a more accurate STI that is closer to the value calculated using the actual impulse response.

[0072] The reverberation delay time τ is the critical distance r from the sound source to the point in the target room space where the sound pressure levels of the direct and indirect sound propagating from the sound source are the same. c It may also be said that this is calculated based on the difference between the sound source and the distance r from the sound source to the receiving point.

[0073] In this way, the reverberation delay time τ can be easily and appropriately set based on predetermined attribute information of the target room space, without requiring specialized knowledge of acoustics.

[0074] The transmission system model for the target indoor space may also be an energy model that assumes the sound pressure energy of sound waves propagating from the sound source is exponentially attenuated.

[0075] In this way, an appropriate transmission system model can be set for the target indoor space without requiring specialized technical skills or knowledge regarding acoustics.

[0076] The attribute information of the target indoor space, which is input information for the transmission system model, may include at least the volume of the target indoor space, the internal surface area, and the average sound absorption coefficient.

[0077] In this way, the architectural designer of a building can easily calculate the STI without the need for the cooperation of an acoustics expert.

[0078] The processing unit 11 may also output and display the calculated STI by dividing it into multiple levels based on the difficulty of hearing at the receiving point.

[0079] In this way, the level of difficulty in hearing corresponding to the calculated STI can be intuitively grasped.

[0080] The series of processes described above can be executed by hardware or by software. In other words, the functional configuration in Figure 3 is merely illustrative and not particularly limited. That is, it is sufficient that the evaluation device 1 is equipped with a function that can execute the series of processes described above as a whole, and the type of functional block used to realize this function is not particularly limited to the example in Figure 3. Furthermore, a single functional block may be composed of hardware alone, software alone, or a combination of both. The functional configuration in this embodiment is realized by a processor that performs arithmetic processing, and processors that can be used in this embodiment include not only those composed of various processing units such as single processors, multiprocessors, and multicore processors, but also those that are combinations of these various processing units with processing circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field-Programmable Gate Arrays).

[0081] When a series of processes are executed by software, the programs that make up that software are installed on a computer or other device from a network or storage medium. The computer may be a computer built into dedicated hardware. Alternatively, the computer may be a computer capable of performing various functions by installing various programs, such as a general-purpose personal computer.

[0082] Such recording media containing programs consist not only of removable media such as USB memory distributed separately from the main unit to the user to provide the program, but also of recording media provided to the user in a state where they are pre-installed in the main unit. Removable media consist of, for example, magnetic disks (including floppy disks), optical disks, or magneto-optical disks. Optical disks consist of, for example, CD-ROMs (Compact Disk-Read Only Memory), DVDs (Digital Versatile Disks), Blu-ray® Discs, etc. Magneto-optical disks consist of, for example, MDs (Mini-Disks). Furthermore, recording media provided to the user in a state where they are pre-installed in the main unit consist of, for example, ROMs on which programs are recorded, hard disks included in the auxiliary storage unit 13, semiconductor memory, etc.

[0083] In this specification, the step of describing a program to be recorded on a recording medium includes not only processes that are performed chronologically in that order, but also processes that are not necessarily performed chronologically, but are executed in parallel or individually.

[0084] Although several embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take on a variety of other embodiments, and it is also possible to combine the above embodiments with their modified configurations. Furthermore, various modifications such as omissions and substitutions can be made without departing from the spirit of the present invention. These embodiments and their variations are included in the scope and spirit of the invention as described herein, and are also included in the scope of the invention and its equivalents as described in the claims. [Explanation of Symbols]

[0085] 1. Indoor space acoustic characteristics evaluation device 11 Processing Section 112 Virtual Impulse Response Generation Unit 113 MTF Calculation Unit 114 STI calculation section 115 Calculation Result Output Section

Claims

1. It is equipped with a processing unit for calculating speech intelligibility in an indoor space, The aforementioned processing unit, Obtain predetermined attribute information regarding the target indoor space that is the subject of speech intelligibility calculation, Based on the predetermined attribute information, the delay time of reverberation at the sound receiving point in the target indoor space is calculated. Based on a transmission system model that simulates the impulse response in the target indoor space as a sound wave transmission system incorporating the delay time of the reverberation sound, the speech intelligibility of the target indoor space is calculated and output. The delay time of the reverberation is calculated based on the difference between the critical distance, which is the distance from the sound source to the point where the sound pressure levels of the direct and indirect sound propagating from the sound source are the same in the target room space, and the distance from the sound source to the receiving point. Indoor space acoustic characteristics evaluation device.

2. The indoor space acoustic characteristics evaluation apparatus according to claim 1, wherein the transmission system model is an energy model that assumes the sound pressure energy of sound waves propagating from a sound source is exponentially attenuated.

3. The indoor space acoustic characteristics evaluation apparatus according to claim 1, wherein the attribute information of the target indoor space, which is input information of the transmission system model, includes at least the volume of the target indoor space, the internal surface area, and the average sound absorption coefficient.

4. The indoor space acoustic characteristics evaluation apparatus according to claim 1, wherein the processing unit divides the calculated speech intelligibility into multiple levels based on the difficulty of hearing at the sound receiving point and outputs and displays them.

5. Computers Obtain predetermined attribute information regarding the target indoor space that is the subject of speech intelligibility calculation, Based on the predetermined attribute information, the delay time of reverberation at the sound receiving point in the target indoor space is calculated. Based on a transmission system model that simulates the impulse response in the target indoor space as a sound wave transmission system incorporating the delay time of the reverberation sound, the speech intelligibility of the target indoor space is calculated and output. The delay time of the reverberation is calculated based on the difference between the critical distance, which is the distance from the sound source to the point where the sound pressure levels of the direct and indirect sound propagating from the sound source are the same in the target room space, and the distance from the sound source to the receiving point. Method for evaluating the acoustic characteristics of an indoor space.

6. On the computer, Obtain predetermined attribute information regarding the target indoor space that is the subject of speech intelligibility calculation, Based on the predetermined attribute information, the delay time of reverberation at the sound receiving point in the target indoor space is calculated. Based on a transmission system model that simulates the impulse response in the target indoor space as a sound wave transmission system incorporating the delay time of the reverberation sound, the system performs a process to calculate and output the speech intelligibility of the target indoor space. The delay time of the reverberation is calculated based on the difference between the critical distance, which is the distance from the sound source to the point where the sound pressure levels of the direct and indirect sound propagating from the sound source are the same in the target room space, and the distance from the sound source to the receiving point. program.

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