Sound field evaluation method, sound field evaluation program, and computer-readable recording medium containing the same.

Abstract

The present invention realizes objective evaluation of a sound field and makes the evaluation of the sound field efficient. A sound-field evaluation method according to the present invention includes: a step S1 for acquiring a sample data group A of impulse responses in a room 1; a step S2 for calculating a base line B corresponding to reverberation attenuation of the impulse responses in a period to be evaluated from a predetermined starting time u1 after a peak C time of an impulse direct sound to a predetermined termination time u2; a step S3 for calculating, on the basis of at least a part of the sample data group A and the base line B, a plurality of evaluation sample values di to be used for evaluating deflection of a sound pressure A of a sample data group with respect to the base line B in the period to be evaluated; a step S4 for calculating an evaluation index g on the basis of the plurality of evaluation sample values di as the representative values or the sums of a plurality of evaluation sample values; and a step S5 for calculating a sound field of the room 1 on the basis of the evaluation index g. The present invention further relates to a sound-field evaluation program for executing the sound-field evaluation method, and a computer-readable recording medium recording the same.

Description

[Technical Field]

[0001] The present invention relates to a sound field evaluation method that enables the evaluation of a room's sound field using objective indicators. The present invention also relates to a sound field evaluation program used to evaluate a room's sound field using objective indicators. The present invention also relates to a computer-readable recording medium on which the sound field evaluation program is recorded. [Background technology]

[0002] In acoustic design, properly evaluating the sound field is crucial for achieving high sound quality. In particular, it is important to evaluate quiet sounds, pleasant sounds, and sounds that facilitate conversation.

[0003] Among these, sound pressure level (dB) is used as an indicator for evaluating quiet sounds. Furthermore, reverberation time is used as an indicator for evaluating good sounds. For example, good sound may be evaluated by the echo time pattern. Additionally, good sound may be evaluated by checking for the presence or absence of unique reflected sounds using model experiments, simulations, etc.

[0004] However, evaluating the ease of speaking among the above is difficult, and various sound field evaluation techniques have been proposed for this purpose. One example of a sound field evaluation technique for evaluating ease of speaking is a technique that evaluates ease of speaking based on the subjective perception of the subject in psychoacoustics (see, for example, Non-Patent Literature 1).

[0005] Instead of evaluating sounds that are easy to talk to, evaluations are being conducted on sounds that are easy to listen to and are similar to sounds that are easy to talk to. A second example of a sound field evaluation technique for evaluating sounds that are easy to listen to is a sound field evaluation technique that uses a sound field simulator to reproduce sound fields of various spaces with different scales and / or acoustic performance, conducts subjective auditory experiments to determine the ease of listening in the reproduced sound fields, and uses acoustic physical indicators that can obtain the most easy-to-listen space found from the results of these auditory experiments to control the acoustic design and the room volume and total surface area of ​​the target space in order to obtain the optimal acoustic space (see, for example, Patent Document 1).

[0006] A third example of sound field evaluation technology for evaluating easily audible sounds is a sound field evaluation technology that evaluates acoustics based on a predetermined database storing at least one of the following: timbre data relating timbre and ACF factor, pitch data relating pitch and ACF factor, and psychological evaluation data relating psychological evaluation values ​​of acoustics and ACF factor, and the calculated ACF factor (see, for example, Patent Document 2).

[0007] A fourth example of sound field evaluation technology for evaluating easily audible sounds is a sound field evaluation technology that performs auditory correction and analysis processing necessary for calculating acoustic figures on the digital signal of the sound to be evaluated and outputs the result, calculates multiple acoustic figures based on this output, and calculates an overall sound quality index from the calculated multiple acoustic figures. In this sound field evaluation technology, the overall sound quality index is calculated based on at least a loudness index related to the volume of sound, a broadband noise index related to broadband noise, a high-frequency pure tone index related to the high-frequency weight of pure tone components, and factor score coefficients related to these indices. The loudness index is calculated based on at least the loudness level, the broadband noise index is calculated based on at least the slope of the approximate straight line of the frequency characteristics, and the high-frequency pure tone index is calculated based on at least the average frequency weighted on multiple peaks on the frequency characteristics. (See, for example, Patent Document 3.) [Prior art documents]

Patent Document

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Document

[0013] To solve the above problems, a sound field evaluation method according to one embodiment is a sound field evaluation method for evaluating the sound field of a room, comprising the steps of: acquiring a sample data group consisting of a plurality of sample data relating to the impulse response of the room, which represents sound pressure on the time axis; calculating a reference line corresponding to the reverberation decay of the impulse response based on the sample data group within an evaluation target period from a predetermined start time to a predetermined end time after the time of peak generation of direct sound due to the impulse; and calculating a plurality of evaluation sample values ​​used to evaluate the fluctuation of sound pressure of the sample data group with respect to the reference line within the evaluation target period, wherein the plurality of evaluation sample values ​​are the plurality of peak-side sound pressure differences between a plurality of peak-side data in the sample data group that have a sound pressure of or greater than the reference line and the reference line absolute value It consists of, or multiple bottom-side sound pressure differences between multiple bottom-side data points in the sample data group that have a sound pressure lower than the reference line and the reference line. absolute value Consists of, or the multiple peak-side sound pressure differences absolute value and the multiple bottom-side sound pressure differences absolute value A process comprising both of the above, and based on the above-mentioned multiple evaluation sample values ​​within the evaluation period Mean, median, mode Alternatively, the process may include the steps of calculating an evaluation index which is a sum, and evaluating the sound field of the room based on the evaluation index.

[0014] To solve the above problems, a sound field evaluation program according to one embodiment is a sound field evaluation program used to evaluate the sound field of a room, comprising: a step of acquiring a group of sample data consisting of a plurality of sample data relating to the impulse response of the room, which represents sound pressure on the time axis; a step of calculating a reference line corresponding to the reverberation decay of the impulse response based on the group of sample data within an evaluation target period from a predetermined start time to a predetermined end time after the time of peak generation of direct sound due to the impulse; and a step of calculating a plurality of evaluation sample values ​​used to evaluate the fluctuation of sound pressure of the group of sample data relative to the reference line within the evaluation target period, wherein the plurality of evaluation sample values ​​are a plurality of peak-side sound pressure differences between a plurality of peak-side data in the group of sample data that have a sound pressure of or greater than the reference line and the reference line. absolute value It consists of, or multiple bottom-side sound pressure differences between multiple bottom-side data points in the sample data group that have a sound pressure lower than the reference line and the reference line. absolute value Consists of, or the multiple peak-side sound pressure differences absolute value and the multiple bottom-side sound pressure differences absolute value A procedure comprising both of the above, and based on the above multiple evaluation sample values ​​within the evaluation period Mean, median, mode Alternatively, the computer may be made to perform a procedure for calculating an evaluation index that is a sum, and a procedure for evaluating the sound field of the room based on the evaluation index.

[0015] One embodiment of the recording medium is a computer-readable recording medium on which the above-mentioned sound field evaluation program is recorded. [Effects of the Invention]

[0016] In one embodiment of the sound field evaluation method, sound field evaluation program, and recording medium, objective evaluation of the sound field can be achieved, and the evaluation of the sound field can be made more efficient. [Brief explanation of the drawing]

[0017] [Figure 1]Figure 1 is a flowchart illustrating a sound field evaluation method according to one embodiment. [Figure 2] Figure 2 is a graph showing a sample data set of room impulse response evaluated by a sound field evaluation method according to one embodiment, and an example of a reference line based thereon. [Figure 3] Figure 3 is a schematic cross-sectional view showing a room evaluated by a sound field evaluation method according to one embodiment. [Figure 4] Figure 4 is a block diagram of a computer that executes a sound field evaluation program according to one embodiment. [Figure 5] Figure 5 is a hardware configuration diagram of an acoustic evaluation system, including a computer that executes a sound field evaluation program according to one embodiment. [Figure 6] Figure 6 is a graph showing the evaluation indicators for Examples 1 to 4. [Figure 7] Figure 7 is a graph showing the total evaluation scores for the auditory performance of Examples 1 to 4. [Figure 8] Figure 8 is a graph showing the evaluation indicators for Examples 5 to 8. [Figure 9] Figure 9 is a graph showing the total evaluation scores for the auditory performance of Examples 5 to 8. [Modes for carrying out the invention]

[0018] A sound field evaluation method, a sound field evaluation program, and a computer-readable recording medium on which the sound field evaluation program is recorded, according to one embodiment, will be described below.

[0019] "Outline of Sound Field Evaluation Methods" Referring to Figures 1-3, the sound field evaluation method according to this embodiment is outlined as follows. The sound field evaluation method evaluates the sound field of Room 1.

[0020] This sound field evaluation method includes a step (data acquisition step) S1 of acquiring a sample data group A consisting of multiple sample data a0 related to the impulse response of room 1. As shown in Figure 2, the impulse response consisting of the sample data group A represents sound pressure on the time axis T (msec).

[0021] In this embodiment, the sound pressure level (dB) is used as the parameter to represent the sound pressure of the impulse response. However, parameters other than the sound pressure level can also be used to represent the sound pressure of the impulse response. For example, parameters other than the sound pressure level include sound pressure (Pa), such as instantaneous sound pressure and peak sound pressure.

[0022] In Figure 2, the vertical axis L represents sound pressure level (dB), and the horizontal axis T represents time (msec). That is, the vertical axis L is the sound pressure level axis, and the horizontal axis T is the time axis. Also, in Figure 2, the solid line B represents the reference line B which will be described next. The impulse response in Figure 2 is also the impulse response of Example 1 which will be described later.

[0023] Referring to Figures 1-3, the sound field evaluation method includes a step (reference line calculation step) S2 to calculate a reference line B corresponding to the reverberation decay of the impulse response based on the sample data group A, within the evaluation period from a predetermined start time u1 to a predetermined end time u2, after the occurrence of the direct sound peak C due to the impulse. Details of the reference line B will be described later.

[0024] The sound field evaluation method involves using multiple evaluation sample values ​​d within the evaluation period described above. i This includes a step (sample value calculation step) S3 to calculate (i=1,...,m, where m is an integer greater than or equal to 2). Multiple evaluation sample values ​​d i This is used to evaluate the fluctuation in sound pressure of sample data group A relative to the reference line B.

[0025] Specifically, multiple evaluation sample values ​​d iIt consists of both a plurality of peak - side sound pressure differences between a plurality of peak - side data a1 with sound pressure above the reference line B and the reference line B in the sample data group A, and a plurality of bottom - side sound pressure differences between a plurality of bottom - side data a2 with sound pressure smaller than the reference line B and the reference line B in the sample data group A. In particular, a plurality of evaluation sample values d i is the absolute value e of a plurality of peak - side sound pressure differences j (j = 1, ···, n, where n is an integer of 2 or more), and the absolute value f of a plurality of bottom - side sound pressure differences between a plurality of bottom - side data a2 and the reference line B k (k = 1, ···, p, where p is an integer of 2 or more), and it is preferably composed of both.

[0026] However, a plurality of evaluation sample values d i can also consist of a plurality of peak - side sound pressure differences, particularly the absolute value e j of them. A plurality of evaluation sample values d i can also consist of a plurality of bottom - side sound pressure differences, particularly the absolute value f k of them.

[0027] The sound field evaluation method includes a step (index calculation step) S4 of calculating an evaluation index g based on a plurality of evaluation sample values d i . The sound field evaluation method also includes a step (sound field evaluation step) S5 of evaluating the sound field of Room 1 based on the evaluation index g. Details of the evaluation index g and details of the sound field evaluation will be described later.

[0028] Furthermore, the sound field evaluation method according to this embodiment can be schematically as follows. Referring to FIG. 2, the evaluation index g can be a representative value of a plurality of evaluation sample values d i during the evaluation target period. Details of the representative value will be described later. However, the evaluation index g can also be the sum of a plurality of evaluation sample values d i during the evaluation target period.

[0029] Furthermore, in the sound field evaluation process S4, in particular, when the evaluation index g is expressed as a positive value, the smaller the evaluation index g, the higher the perceived auditory evaluation performance of the sound field of room 1 is evaluated. For example, the evaluation sample value d i If the expression consists of absolute values, the evaluation index g is represented by a positive value. However, if the evaluation index g is represented by a negative value, a larger evaluation index g indicates that the auditory evaluation performance of the sound field in Room 1 can be evaluated as higher.

[0030] Here, auditory evaluation performance indicates the degree of sound quality determined based on a person's judgment when listening to sounds such as music, female voice announcements, and male voice announcements emitted from speaker 2 in room 1. In the embodiment described later, when the evaluation index g is represented by a positive value, it has been confirmed that the auditory evaluation performance of the sound field in room 1 increases as the evaluation index g decreases. Therefore, it is clear that the relationship between the evaluation index g and auditory evaluation performance can be determined proportionally.

[0031] "Details of the sound field evaluation method" Referring to Figures 1 and 2, the sound field evaluation method can be described in detail as follows. As shown in Figure 2, the reference line B can be an approximate straight line, approximate curve, regression line, regression curve, etc., determined based on the reverberation decay of the impulse response according to the sample data group A within the evaluation period. If the reference line B is a straight line such as an approximate straight line or regression line, linear approximation based on the least squares method, etc., can be used. If the reference line B is a curve such as an approximate curve or regression curve, exponential approximation, logarithmic approximation, polynomial approximation, power approximation, etc., can be used.

[0032] In particular, the reference line B can be a reverberation decay line, reverberation decay curve, etc., determined based on the reverberation decay of the impulse response according to the sample data group A within the evaluation period. In many cases, the reference line B can be a reverberation decay line. The evaluation period includes the early reflection period and the late reverberation period. For example, the early reflection period can be the range from approximately 50 msec to approximately 300 msec after the first reflected sound arrives at the measurement position of the impulse sound with the microphone installed. For example, the late reverberation period can be the range from the end of the early reflection period onward. However, the evaluation period can also be limited to the early reflection period only, or to the late reverberation period only.

[0033] Multiple evaluation sample values ​​d i However, when the data consists of both multiple peak-side sound pressure differences and multiple bottom-side sound pressure differences, the sum of the number of samples n of the peak-side data a1 and the number of samples p of the bottom-side data a2 becomes the number of samples m (=n+p) used to calculate the evaluation index g (hereinafter referred to as the "evaluation sample count" as needed). The evaluation sample count m corresponds to the number of samples in the sample data group A within the evaluation period.

[0034] However, multiple evaluation sample values ​​d i However, in the case of multiple peak-side sound pressure differences, the number of samples n of the peak-side data a1 becomes the number of evaluation samples m (=n). Multiple evaluation sample values ​​d i However, in the case of multiple bottom-side sound pressure differences, the number of samples p of the bottom-side data a2 becomes the number of evaluation samples m (=p).

[0035] Referring to Figures 1 and 2, the representative value used as the evaluation index g is a set of multiple evaluation sample values ​​d. i The mean can be the mean, median, or mode of the above multiple evaluation sample values ​​d. i This is the sum of the values ​​divided by the number of evaluation samples, m.

[0036] "Conditions for acquiring sample data sets of impulse response" Referring to Figure 3, the conditions for acquiring sample data group A of the impulse response can be as follows in detail. Sample data group A of the impulse response can be acquired by either actual measurement or sound field simulation.

[0037] When acquiring sample data set A of the impulse response by actual measurement, the impulse sound emitted from speaker 2 in room 1 is measured using microphones 3a and 3b. The analog signals output from microphones 3a and 3b are acquired through this measurement, and the acquired analog signals are subjected to digital signal processing to acquire sample data set A of digital signals. The acquired sample data set A of digital signals is then converted to represent sound pressure level (dB) on the time axis T (msec). This sample data set A is then acquired as the impulse response.

[0038] When acquiring sample data set A of impulse responses by sound field simulation, numerical calculations are performed based on conditions set to measure the impulse sound emitted from speaker 2 in room 1 using microphones 3a and 3b, and sample data set A of impulse responses is obtained as a result of these numerical calculations.

[0039] In actual measurements, sample data set A of impulse response based on room 1, which is empty, can be obtained. In addition, in actual measurements, sample data set A of impulse response based on room 1, which is equipped with acoustic modifiers such as sound diffusers, sound reflectors, and sound absorbers, can be obtained.

[0040] In the case of sound field simulation, it is possible to obtain a sample data set A of impulse responses based on the quantified data of Room 1, which is an empty room. Furthermore, it is possible to obtain a sample data set A of impulse responses based on the quantified data of Room 1, which has an acoustic adjustment device installed.

[0041] To explain acoustic diffusers, acoustic reflectors, and acoustic absorbers, an acoustic diffuser typically has multiple columnar sections that can reflect incoming sound in order to provide acoustic diffusion properties that diffuse the incoming sound. Acoustic diffusers may also be configured to provide acoustic reflection properties in addition to acoustic diffusion properties. For example, an example of an acoustic diffuser is the columnar diffuser of the Acoustic Grove® System (AGS).

[0042] Next, an acoustic reflector has acoustic reflection properties that reflect incoming sound. Examples of acoustic reflectors include acoustic reflectors. A sound absorber has sound absorption properties that allow it to absorb incoming sound. Examples of such sound absorbers include sound-absorbing cushions made of porous materials such as glass wool and rock wool.

[0043] In both such direct measurements and sound field simulations, a room 1 equipped with at least one of the following can be used as the evaluation target: an acoustic diffuser, an acoustic reflector, and an acoustic absorber. For example, an acoustic modifier can be placed in at least one of the first placement area Y1 and the second placement area Y2, which are shown in Figure 3 as two hatched areas Y1 and Y2, respectively, consisting of multiple diagonal lines. However, the placement area of ​​the acoustic modifier is not limited to this.

[0044] "The relationship between evaluation metrics and auditory performance evaluation." Referring to Figures 2 and 3, the relationship between the evaluation index g and the auditory evaluation performance is as follows: The auditory evaluation performance and evaluation index g of Room 1 change under certain conditions depending on changes in the type and placement range of the acoustic modifiers installed in Room 1. Furthermore, the auditory evaluation performance and evaluation index g of Room 1 also change under certain conditions depending on the presence or absence of acoustic modifiers in Room 1.

[0045] As will become clear from the examples described later, this consistent relationship means that as the evaluation index g decreases, the auditory evaluation performance increases. Therefore, it is possible to derive an evaluation of subjective auditory evaluation performance from an evaluation of the objective evaluation index g.

[0046] "Sound field evaluation program and recording medium" Referring to Figures 2-5, the sound field evaluation program and recording medium according to this embodiment can be as follows. The sound field evaluation program is used to evaluate the sound field of room 1.

[0047] The sound field evaluation program causes the computer 10 to execute a procedure (data acquisition procedure) to acquire a sample data group A consisting of multiple sample data a0 relating to the impulse response of room 1, which represents sound pressure on the time axis T (msec). The sound field evaluation program causes the computer 10 to execute a procedure (reference line calculation procedure) to calculate a reference line B corresponding to the reverberation decay of the impulse response of room 1 based on the sample data group A within the evaluation period from a predetermined start time u1 to a predetermined end time u2, which is after the occurrence of the direct sound peak C due to the impulse.

[0048] The sound field evaluation program uses multiple evaluation sample values ​​d within the evaluation period described above. i The computer 10 is instructed to execute the procedure for calculating multiple evaluation sample values ​​d. i This is used to evaluate the fluctuation in sound pressure of sample data group A relative to the reference line B.

[0049] Specifically, multiple evaluation sample values ​​d i This consists of both multiple peak-side sound pressure differences between multiple peak-side data a1, which have sound pressure levels above the reference line B within sample data group A, and the reference line B, and multiple bottom-side sound pressure differences between multiple bottom-side data a2, which have sound pressure levels below the reference line B within sample data group A, and the reference line B. In particular, multiple evaluation sample values ​​d i e is the absolute value of the multiple peak sound pressure differences. j(j=1,...,n, where n is an integer greater than or equal to 2) and the absolute value f of the multiple bottom-side sound pressure differences between multiple bottom-side data a2 and the reference line B k It is desirable that it consists of both (k=1, ..., p, where p is an integer greater than or equal to 2) and (k=1, ..., p).

[0050] However, multiple evaluation sample values ​​d i This refers to multiple peak-side sound pressure differences, particularly their absolute value e j It can also consist of multiple evaluation sample values ​​d. i This refers to multiple bottom-side sound pressure differences, particularly their absolute value f k It can also consist of

[0051] The sound field evaluation program uses multiple evaluation sample values ​​d i The computer 10 is instructed to perform a procedure (index calculation procedure) to calculate the evaluation index g based on the above. The sound field evaluation program is also instructed to perform a procedure (sound field evaluation procedure) to evaluate the sound field of room 1 based on the evaluation index g.

[0052] Furthermore, the recording medium according to this embodiment is a computer-readable recording medium on which such a sound field evaluation program is recorded. Examples of recording media include semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory, optical discs such as CD-ROM, DVD-ROM, and Blu-ray, and magnetic discs.

[0053] Furthermore, the sound field evaluation program according to this embodiment can be made as follows. Referring to Figure 2, the evaluation index g is a plurality of evaluation sample values ​​d within the evaluation period. i This is a representative value. However, the evaluation index g is based on multiple evaluation sample values ​​d within the evaluation period. i It can also be expressed as the sum of [the numbers].

[0054] Furthermore, in the sound field evaluation procedure, when the evaluation index g is expressed as a positive value, a smaller evaluation index g indicates a higher perceived auditory performance of the sound field in Room 1. Conversely, when the evaluation index g is expressed as a negative value, a larger evaluation index g indicates a higher perceived auditory performance of the sound field in Room 1.

[0055] In such a sound field evaluation program, the data acquisition procedure involves having the computer 10 execute the data acquisition process S1 of the sound field evaluation method. The reference line calculation procedure involves having the computer 10 execute the reference line calculation process S2 of the sound field evaluation method. The sample value calculation procedure involves having the computer 10 execute the sample value calculation process S3 of the sound field evaluation method. The index calculation procedure involves having the computer 10 execute the index calculation process S4 of the sound field evaluation method. The sound field evaluation procedure involves having the computer 10 execute the sound field evaluation process S5 of the sound field evaluation method.

[0056] "Sound field evaluation system" Referring to Figures 4 and 5, an acoustic evaluation system configured as hardware including a sound field evaluation program and a recording medium according to this embodiment will be described. The acoustic evaluation system includes a computer 10 capable of executing the sound field evaluation program as described above.

[0057] The computer 10 can also be called the acoustic evaluation device 10. As shown in Figure 4, the computer 10, referred to as the acoustic evaluation device 10, includes a data acquisition unit 10a that performs a data acquisition procedure, a reference line calculation unit 10b that performs a reference line calculation procedure, a sample value calculation unit 10c that performs a sample value calculation procedure, an index calculation unit 10d that performs an index calculation procedure, and a sound field evaluation unit 10e that performs a sound field evaluation procedure.

[0058] As shown in Figure 5, computer 10 is also configured as a server. Such an acoustic evaluation system has at least one terminal device 20 that is directly or indirectly connected to computer 10 in a communicative manner. The terminal device 20 can be a personal computer, smartphone, tablet computer, etc.

[0059] Computer 10 includes a bus 11, a CPU (Central Processing Unit) 12, an HDD (Hard Disk Drive) 13, RAM (Random Access Memory) 14, ROM (Read Only Memory) 15, a communication interface 16, and an input / output interface 17. Furthermore, computer 10 may also include an optical disc drive 18 capable of reading optical discs and a flash memory 19 that is removable from computer 10. The CPU 12, HDD 13, RAM 14, ROM 15, communication interface 16, input / output interface 17, optical disc drive 18, and flash memory 19 are connected directly or indirectly via the bus 11.

[0060] The terminal device 20 also has a bus 21, a CPU 22, an HDD 23, a RAM 24, a ROM 25, a communication interface 26, and an input / output interface 27. The CPU 22, HDD 23, RAM 24, ROM 25, communication interface 26, and input / output interface 27 are connected directly or indirectly via the bus 21. The communication interface 26 of each terminal device 20 is connected to the communication interface 16 of the computer 10 via the communication network 30.

[0061] An input device 28 and an output device 29 are connected to the input / output interface 27 of the terminal device 20. The input device 28 can be a keyboard, mouse, etc. The output device 29 can be a display, printer, etc. However, instead of separate input and output devices, an input / output device configured to integrate the input and output devices, such as a touch panel display, can also be used.

[0062] In this acoustic evaluation system, input information from the input device 28 is sent from the terminal device 20 to the computer 10 via the communication network 30. In the computer 10, the acoustic evaluation program recorded on its recording medium, the HDD 13, is executed by calculations performed by the CPU 12 and other components based on the input information sent in this way, and as a result, sound field evaluation information for room 1 is obtained. The sound field evaluation information is sent from the computer 10 to each terminal device 20 via the communication network 30 as described above. The sound field evaluation information sent in this way is output to the output device 29.

[0063] Furthermore, the sample data set A of the impulse response can also be recorded on the HDD 13, which is the recording medium of the computer 10. As described above, this sample data set A can be obtained by inputting measured data into the computer 10, or by sound field simulation on the computer 10 or terminal device 20.

[0064] However, the input information can also be obtained from an input device connected to the computer's input / output interface. The room's acoustic field evaluation information obtained by running the acoustic evaluation program can also be output to an output device connected to the computer's input / output interface. Furthermore, at least one of the acoustic evaluation program and the sample data set can be recorded on an optical disc readable by the computer's optical disc drive, or on a flash memory that can be attached to the computer.

[0065] As described above, the sound field evaluation method according to this embodiment is a sound field evaluation method for evaluating the sound field of room 1, comprising: step S1 acquiring a sample data group A consisting of a plurality of sample data a0 relating to the impulse response of room 1, which represents sound pressure on a time axis T; step S2 calculating a reference line B corresponding to the reverberation decay of the impulse response of room 1 based on the sample data group A within an evaluation target period from a predetermined start time u1 to a predetermined end time u2 after the occurrence of the direct sound peak C due to the impulse; and a plurality of evaluation sample values ​​d used to evaluate the fluctuation of the sound pressure of the sample data group A relative to the reference line B within the evaluation target period. i Step S3 is to calculate the plurality of evaluation sample values ​​d i However, step S3 consists of a plurality of peak-side sound pressure differences between a plurality of peak-side data a1, which have a sound pressure of sound pressure equal to or greater than the reference line B, and the reference line B, or a plurality of bottom-side sound pressure differences between a plurality of bottom-side data a2, which have a sound pressure of sound pressure less than the reference line B, and the reference line B, or a plurality of peak-side sound pressure differences and a plurality of bottom-side sound pressure differences, and the plurality of evaluation sample values ​​d i The process includes a step S4 to calculate an evaluation index g based on the evaluation index g, and a step S5 to evaluate the sound field of the room 1 based on the evaluation index g.

[0066] The sound field evaluation program according to this embodiment is a sound field evaluation program for evaluating the sound field of room 1, and includes the steps of: acquiring a sample data group A consisting of a plurality of sample data a0 relating to the impulse response of room 1, which represents sound pressure on a time axis T; calculating a reference line B corresponding to the reverberation decay of the impulse response of room 1 based on the sample data group A within an evaluation target period from a predetermined start time u1 to a predetermined end time u2 after the occurrence of the direct sound peak C due to the impulse; and a plurality of evaluation sample values ​​d used to evaluate the fluctuation of the sound pressure of the sample data group A relative to the reference line B within the evaluation target period. i A procedure for calculating the plurality of evaluation sample values ​​d iThe procedure consists of a plurality of peak-side sound pressure differences between a plurality of peak-side data a1, which have a sound pressure of sound pressure equal to or greater than the reference line B, and the reference line B, or a plurality of bottom-side sound pressure differences between a plurality of bottom-side data a2, which have a sound pressure of sound pressure equal to or less than the reference line B, and the reference line B, or a procedure consisting of both the plurality of peak-side sound pressure differences and the plurality of bottom-side sound pressure differences, and the plurality of evaluation sample values ​​d i The computer 10 is instructed to perform the following steps: calculate an evaluation index g based on the above, and evaluate the sound field of room 1 based on the evaluation index g.

[0067] According to these sound field evaluation methods and programs, a reference line B can be easily calculated from a sample data set A of impulse response of room 1, which represents sound pressure on the time axis T. Furthermore, an evaluation index g used for sound field evaluation can be easily calculated using at least one of multiple peak-side sound pressure differences and multiple bottom-side sound pressure differences based on this reference line B. As a result, sound field evaluation can be made more efficient.

[0068] Furthermore, the evaluation index g is derived from a set of objective evaluation sample values ​​d, which are based on an objective baseline B derived from a sample data set A of impulse response in room 1. i Since it is calculated based on [a specific factor], it serves as an objective indicator. Therefore, an objective sound field evaluation can be achieved based on the objective evaluation indicator g. In other words, according to the sound field evaluation method and sound field evaluation program of this embodiment, an objective sound field evaluation can be achieved, and the evaluation of the sound field can be made more efficient.

[0069] In each of the sound field evaluation methods and programs according to this embodiment, the evaluation index g is the plurality of evaluation sample values ​​d within the evaluation period. i This represents a representative value or sum. Therefore, the sound field of Room 1 can be objectively evaluated using a quantitative representative value or sum.

[0070] In the sound field evaluation method and program according to this embodiment, the smaller the evaluation index g, the higher the perceived auditory evaluation performance of the sound field in room 1. Therefore, the sound field can be easily evaluated based on a proportional change in perceived auditory evaluation performance with respect to the magnitude of the evaluation index g, that is, the magnitude of the representative value or sum. As a result, the evaluation of the sound field can be performed simply and clearly, and as a result, the evaluation of the sound field can be made more efficient.

[0071] The computer-readable recording medium according to this embodiment contains the above-mentioned sound field evaluation program. Therefore, using such a recording medium, it is possible to obtain effects similar to those obtained by the above-mentioned sound field evaluation program.

[0072] Although embodiments of the present invention have been described so far, the present invention is not limited to the embodiments described above, and the present invention can be modified and changed based on its technical concept. [Examples]

[0073] Examples 1 to 8 will be described below. First, referring to Figure 3, the rooms 1 and their internal conditions used in each of Examples 1 to 8 will be described. The shape of room 1 was a roughly rectangular shape in plan view, with the depth being longer than the width. The depth D of room 1 was 5150 mm, and the width W of room 1 was 3950 mm. Although not specifically shown in the illustration, the height of room 1 was 2600 mm.

[0074] In Room 1, the back wall 1a in the depth direction, the front wall 1b in the depth direction, the left wall 1c in the width direction when viewed towards the back wall 1a, and the right wall 1d in the width direction when viewed towards the back wall 1a are made of gypsum board and wallpaper attached to the inner surface of the gypsum board facing the interior of Room 1. The floor 1e is made of wooden flooring material. The ceiling (not shown) is made of plywood, wallpaper attached to the inner surface of the plywood facing the interior of Room 1, and sound-absorbing material partially attached to the inner surface of the wallpaper facing the interior of Room 1.

[0075] In such a room 1, the acoustic modifier was placed in either the first or second placement area Y1 or Y2, which are indicated as two hatched areas Y1 and Y2, respectively, consisting of multiple diagonal lines. As will be described in detail later, in Examples 1 to 8, the acoustic modifier was installed in either of these first or second placement areas Y1 or Y2.

[0076] Specifically, the first and second placement areas Y1 and Y2 were positioned along the left wall 1c. The depth of each of the first and second placement areas Y1 and Y2 was 1200 mm. The center of the first placement area Y1 was set to be 1560 mm away from the back wall 1a. The center of the second placement area Y2 was set to be 3680 mm away from the back wall 1a.

[0077] The widthwise length, i.e., thickness, of the first and second placement areas Y1 and Y2 was changed according to the type of acoustic modifier. The first and second placement areas Y1 and Y2 were set to extend upward from the floor 1e in the height direction. The height of the first and second placement areas Y1 and Y2 was also changed according to the type of acoustic modifier.

[0078] The positions of speaker 2 and microphones 3a and 3b will be described below.

[0079] Speaker 2 was positioned so that its sound source was 1450 mm away from the back wall 1a in the depth direction. Speaker 2 was positioned so that its sound source was 1900 mm away from the left wall 1c in the width direction. Speaker 2 was positioned so that its sound source was 1030 mm away from the floor in the height direction. In addition, in a cross-sectional view, Speaker 2 was oriented so that it emitted sound diagonally from its sound source toward the front wall 1b and the left wall 1c.

[0080] Two microphones, 3a and 3b, were placed in Room 1. One of the two microphones, 3a, was placed at the back of Room 1 in the depth direction. The other microphone, 3b, was placed at the front of Room 1 in the depth direction. Hereafter, one microphone 3a will be referred to as the first microphone 3a, and the other microphone 3b as the second microphone 3b, as needed.

[0081] The first microphone 3a was positioned 2100 mm away from the back wall 1a in the depth direction. The second microphone 3b was positioned 3600 mm away from the back wall 1a in the depth direction. The first and second microphones 3a and 3b were each positioned 900 mm away from the left wall 1c in the width direction. The first and second microphones 3a and 3b were each positioned 1030 mm away from the floor in the height direction.

[0082] Next, the calculation of the evaluation index g will be explained. In each of Examples 1 to 8, first, the impulse sound emitted from speaker 2 was measured using the first or second microphones 3a and 3b, respectively. Based on the measurements using the first or second microphones 3a and 3b, a sample data set A of the impulse response was obtained.

[0083] The absolute value e of the multiple peak sound pressure differences mentioned above j and the absolute value f of the multiple bottom-side sound pressure differences k The average value based on the sum of the values ​​was calculated as the evaluation index g. The evaluation period was defined as a range of 300 msec, starting 2 msec after the occurrence of the direct sound peak C due to the impulse.

[0084] Furthermore, we will explain the evaluation of auditory performance, which was conducted to clarify the relationship between the evaluation index g and auditory performance. In each of Examples 1 to 8, each of the seven subjects listened to music, a female voice announcement, and a male voice announcement emitted from speaker 2 with their ears positioned at the positions of the first or second microphones 3a and 3b. Each subject then compared the quality of the sounds they heard under these conditions.

[0085] The conditions for each of Examples 1 to 8 will now be described. Regarding the acoustic modifier, in Examples 1 and 5, glass wool, a type of sound absorber, was installed in the first placement area Y1. In Examples 2 and 6, the same glass wool as in Examples 1 and 5 was installed in the second placement area Y2. Specifically, a total of four pieces of glass wool were placed in the first or second placement area Y1 or Y2, with two pieces arranged in the depth direction and two pieces arranged in the height direction. The length of each piece of glass wool in the depth direction was 600 mm, and the height of each piece of glass wool was 900 mm.

[0086] In Examples 3 and 7, an ANKH of the Acoustic Grove® System (AGS), a type of sound diffuser, was installed in the first placement area Y1. In Examples 4 and 8, an ANKH of the same AGS as in Examples 3 and 7 was installed in the second placement area Y2. Specifically, two ANKHs of the AGS were placed side by side in the depth direction in the first or second placement area Y1 or Y2. The depth of each ANKH of the AGS was 600 mm, and the height of each ANKH of the AGS was 1500 mm.

[0087] Furthermore, in each of Examples 1 to 4, the first microphone 3a was used, and in each of Examples 5 to 8, the second microphone 3b was used. Under these conditions, the evaluation index g for Examples 1 to 8 was calculated, and then the evaluation index g for Examples 1 to 4 and the evaluation index g for Examples 5 to 8 were compared.

[0088] Furthermore, under the above conditions, the auditory evaluation performance of Examples 1-4 was compared, and the auditory evaluation performance of Examples 5-8 was also compared. Specifically, in the comparison of auditory evaluation performance of Examples 1-4 and the comparison of auditory evaluation performance of Examples 5-8, each of the seven subjects ranked the sound quality of each example.

[0089] In this ranking, the first-ranked example was given 1 point, the second-ranked example 2 points, the third-ranked example 3 points, and the fourth-ranked example 4 points. If it was not possible to rank multiple examples, the average of the score for the current rank and the score for the subsequent rank (which was skipped) was assigned to each example. For example, if two examples both received a first-ranked evaluation, the score assigned to each of these two examples would be 1.5 points, which is the average of the 1 point for the first-ranked example and the 2 points for the second-ranked example (which was skipped).

[0090] Then, the evaluation scores assigned to each embodiment were totaled according to the ranking results of all seven subjects. The embodiments were then arranged in descending order of total evaluation scores, and the auditory evaluation performance was evaluated as improving according to this order.

[0091] Based on the above, the calculation results of the evaluation index g for Examples 1 to 4 are shown in Figure 6, and the evaluation results of the auditory evaluation performance for Examples 1 to 4 are shown in Figure 7. In Figure 6, the vertical axis G represents the evaluation index g (dB) shown as the average value (dB), and in Figure 7, the vertical axis Z represents the total evaluation score (points).

[0092] Referring to Figure 6, the evaluation index g for Examples 1, 2, 3, and 4 were 1.65 dB, 1.71 dB, 1.50 dB, and 1.52 dB, respectively. In other words, when comparing the evaluation index g for Examples 1 to 4, it was confirmed that the evaluation index g decreased in the order of Example 2, Example 1, Example 4, and Example 3.

[0093] Referring to Figure 7, the total evaluation scores for Examples 1, 2, 3, and 4 were 22.5 points, 24.5 points, 10 points, and 13 points, respectively. In other words, in the comparison of the auditory evaluation performance of Examples 1 to 4, it was confirmed that the auditory evaluation performance improved in the order of Example 2, Example 1, Example 4, and Example 3. Therefore, it was confirmed that in Examples 1 to 4, auditory evaluation performance improved as the evaluation index g decreased.

[0094] Furthermore, the calculation results of the evaluation index g for Examples 5 to 8 are shown in Figure 8, and the evaluation results of the auditory evaluation performance for Examples 5 to 8 are shown in Figure 9. In Figure 8, the vertical axis G represents the evaluation index g (dB) shown as the average value (dB), and in Figure 9, the vertical axis Z represents the total evaluation score (points).

[0095] Referring to Figure 8, the evaluation index g for Examples 5, 6, 7, and 8 were 1.80 dB, 1.81 dB, 1.63 dB, and 1.53 dB, respectively. In other words, when comparing the evaluation index g for Examples 5 to 8, it was confirmed that the evaluation index g decreased in the order of Example 6, Example 5, Example 7, and Example 8.

[0096] Referring to Figure 9, the total evaluation scores for Examples 5, 6, 7, and 8 were 23 points, 23.5 points, 13 points, and 10.5 points, respectively. In other words, in the comparison of the auditory evaluation performance of Examples 5 to 8, it was confirmed that the auditory evaluation performance improved in the order of Example 6, Example 5, Example 7, and Example 8. Therefore, it was also confirmed that in Examples 5 to 8, auditory evaluation performance improved as the evaluation index g decreased. [Explanation of Symbols]

[0097] 1… Room T...Horizontal axis, time axis, A...Sample data set, a0...Sample data, a1...Peak side data, a2...Bottom side data, B...Solid line, baseline, C...Direct sound peak, d i ...evaluation sample value, g...evaluation index, u1...start time, u2...end time S1… Project, Data Acquisition Project, S2… Project, Baseline Calculation Project, S3… Project, Calculation of Sum Value, S4… Project, Index Calculation Project, S5… Project, Sound Field Evaluation Project

Claims

1. A sound field evaluation method for evaluating the sound field of a room, A step of acquiring a group of sample data consisting of multiple sample data relating to the impulse response of the room, which represents sound pressure on the time axis, A step of calculating a reference line corresponding to the reverberation decay of the impulse response based on the sample data set within an evaluation period from a predetermined start time to a predetermined end time, after the time of direct sound peak generation due to the impulse, A step of calculating a plurality of evaluation sample values ​​used to evaluate the fluctuation of sound pressure of the sample data group with respect to the reference line within the evaluation period, wherein the plurality of evaluation sample values ​​consist of the absolute values ​​of a plurality of peak-side sound pressure differences between a plurality of peak-side data in the sample data group that have a sound pressure of or greater than the reference line and the reference line, or consist of the absolute values ​​of a plurality of bottom-side sound pressure differences between a plurality of bottom-side data in the sample data group that have a sound pressure of less than the reference line and the reference line, or consist of both the absolute values ​​of the plurality of peak-side sound pressure differences and the absolute values ​​of the plurality of bottom-side sound pressure differences. A step of calculating an evaluation index which is the mean, median, mode, or sum of the multiple evaluation sample values ​​within the evaluation period, based on the multiple evaluation sample values, A step of evaluating the sound field of the room based on the aforementioned evaluation index. A sound field evaluation method that includes this.

2. The sound field evaluation method according to claim 1, wherein in the step of evaluating the sound field of the room, the smaller the evaluation index, the higher the perceived auditory evaluation performance of the sound field of the room.

3. A sound field evaluation program used to evaluate the sound field of a room, A procedure for obtaining a set of sample data consisting of multiple sample data relating to the impulse response of the room, which represents sound pressure on the time axis, A procedure for calculating a reference line corresponding to the reverberation decay of the impulse response based on the sample data set within an evaluation period from a predetermined start time to a predetermined end time, after the time of direct sound peak generation due to the impulse, A procedure for calculating a plurality of evaluation sample values ​​used to evaluate the fluctuation of sound pressure of the sample data group with respect to the reference line within the evaluation period, wherein the plurality of evaluation sample values ​​consist of the absolute values ​​of a plurality of peak-side sound pressure differences between a plurality of peak-side data points in the sample data group that have a sound pressure of or greater than the reference line and the reference line, or consist of the absolute values ​​of a plurality of bottom-side sound pressure differences between a plurality of bottom-side data points in the sample data group that have a sound pressure of less than the reference line and the reference line, or consist of both the absolute values ​​of the plurality of peak-side sound pressure differences and the absolute values ​​of the plurality of bottom-side sound pressure differences. A procedure for calculating an evaluation index that is the mean, median, mode, or sum of the multiple evaluation sample values ​​within the evaluation period, based on the multiple evaluation sample values, A procedure for evaluating the sound field of the room based on the aforementioned evaluation index, and A sound field evaluation program to be executed by a computer.

4. The sound field evaluation program according to claim 3, wherein, in the procedure for evaluating the sound field of the aforementioned room, the smaller the evaluation index, the higher the perceived auditory evaluation performance of the sound field of the aforementioned room.

5. A computer-readable recording medium that stores the sound field evaluation program described in claim 3 or 4.

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