WO2024084811A1 - Acoustic characteristic analysis system and acoustic characteristic analysis method - Google Patents

Abstract

Provided are an acoustic characteristic analysis system and the like which enable a user to experience, in a simulated manner, a sound from a sound source audible in a prescribed acoustic space. The acoustic characteristic analysis system comprises a control unit that outputs, as an audible signal and on the basis of characteristics of an acoustic space (1) which is a real space or a virtual space, a reception sound signal to be received when a user experiences, in a simulated manner, a sound from a prescribed sound source (2) audible in the acoustic space (1). The control unit measures reverberation time on the basis of a prescribed sound collected in the acoustic space (1) by a sound collection device (20), and calculates an average sound absorption rate on the basis of the dimensions of the acoustic space (1) and the reverberation time.

Description

Acoustic characteristic analysis system and acoustic characteristic analysis method

The present invention relates to an acoustic characteristic analysis system, etc.

As a technique for evaluating how sound resonates in a predetermined acoustic space, for example, the techniques described in Patent Documents 1 and 2 are known. That is, Patent Document 1 describes "a technique for evaluating the reduction of input sound by the arrangement of sound absorbing means."
Furthermore, Patent Document 2 describes that "the noise level at a sound receiving position is predicted from the incident energy from each element to the sound receiving position, taking into account reflection, multiple diffraction, and sound transmission."

JP 2012-68384 A JP 2003-75244 A

The technologies described in Patent Documents 1 and 2 evaluate the sound in an acoustic space based on indices such as sound pressure level, but do not describe any technology that allows a user to simulate the experience of the sound of a sound source heard in a specified acoustic space.

The present invention aims to provide an acoustic characteristic analysis system that allows a user to virtually experience the sound of a sound source heard in a specified acoustic space.

In order to solve the above problems, the acoustic characteristic analysis system according to the present invention is provided with a control unit that outputs, as an audible signal, a received sound signal that is received when a user simulates the experience of hearing the sound of a specific sound source in an acoustic space, which may be a real space or a virtual space, based on the characteristics of the acoustic space.

The present invention provides an acoustic characteristic analysis system that allows a user to simulate the experience of hearing the sound of a sound source in a specified acoustic space.

FIG. 1 is an explanatory diagram of an acoustic space that is a target of an acoustic characteristic analysis system according to a first embodiment. 1 is a functional block diagram of an acoustic characteristic analysis system according to a first embodiment. FIG. FIG. 2 is a front view of a smartphone equipped with a display as an example of a display device of the acoustic characteristic analysis system according to the first embodiment. 5 is a flowchart showing a process executed by a control unit of the acoustic characteristic analysis system according to the first embodiment. FIG. 11 is a functional block diagram of an acoustic characteristic analysis system according to a second embodiment. 13 is an explanatory diagram showing a situation in which a specific character is using a vacuum cleaner, which is a sound source, in the acoustic characteristic analysis system according to the third embodiment. FIG. FIG. 13 is an explanatory diagram of an acoustic space that is a target of an acoustic characteristic analysis system according to a sixth embodiment. FIG. 23 is an explanatory diagram of an acoustic space that is a target of an acoustic characteristic analysis system according to a seventh embodiment.

First Embodiment
<Target of acoustic characteristic analysis system>
FIG. 1 is an explanatory diagram of an acoustic space 1 that is a target of the acoustic characteristic analysis system according to the first embodiment.
The acoustic characteristic analysis system 100 (see FIG. 2) is a system for allowing a user to simulate an experience of a sound heard from a sound source 2 in a specific acoustic space 1. In the first embodiment, a case will be described in which the acoustic space 1 is a real space (a space that actually exists). An example of such an acoustic space 1 is a room in a building such as a house or a building, but the acoustic space 1 is not limited to this. That is, the acoustic space 1 may be a space in a moving body such as a car or a railroad vehicle, a ship or an airplane, or a space in an elevator car. In addition, the acoustic space 1 may be a large space such as a sales floor of a department store or a concert hall, or may be a specific space that exists underground.

As shown in FIG. 1, acoustic space 1 is made up of side surfaces 1a and 1b, as well as a ceiling surface 1c and a floor surface 1d. In acoustic space 1, certain objects 3 such as desks, chairs, and shelves are placed. In addition, although not shown in FIG. 1, acoustic space 1 often has windows and doors installed.

The sound source 2 shown in FIG. 1 is a device whose operating sound (product sound) is the subject of a simulated experience by the user. Examples of such sound sources 2 include home appliances such as vacuum cleaners, washing machines, and air conditioners, as well as microwave ovens and televisions, but other devices are also possible. For example, when a user is considering purchasing a certain device that he or she found through an Internet search, the user can use the acoustic characteristics analysis system 100 (see FIG. 2) to simulate an experience of how the operating sound of the device sounds in an acoustic space 1 (such as the living room of the user's home).

The sound source 2 shown in FIG. 1 is illustrated for the sake of convenience to show the location of a specific device that a user is considering purchasing (i.e., sound source 2) when it is assumed that the device is placed in acoustic space 1, but there is no particular need for the device to actually be placed in acoustic space 1. This is because the specific device is the subject of a user's simulated experience of its operating sound, and there is no particular need for it to actually be installed in acoustic space 1.

In addition, although the noise level (or A-weighted sound pressure level close to human hearing) of the operating sound of the equipment may be written in the specifications of the equipment, the noise level alone does not allow the user to experience what the operating sound of the equipment actually sounds like. In addition, noise level evaluations are generally performed in anechoic chambers (not shown) that minimize the effects of reflected sound, but in rooms where the equipment is actually used, sound is reflected by the walls, so the way the sound resonates is different from that in an anechoic chamber. Therefore, in the first embodiment, an acoustic characteristic analysis system 100 (see FIG. 2) is used to allow the user to simulate an experience of the operating sound of the equipment (sound source 2 in FIG. 1) in a specified acoustic space 1. This can be used as a basis for the user's decision when considering purchasing the equipment.

The receiver 4 shown in FIG. 1 is shown as a sound receiving position when listening to the sound of the sound source 2 in the acoustic space 1. The sound pickup device 20 is a device that picks up sound in the acoustic space 1. For example, a microphone is used as such a sound pickup device 20. The x-axis, y-axis, and z-axis shown in FIG. 1 will be described later.

<Configuration of Acoustic Characteristic Analysis System>
FIG. 2 is a functional block diagram of the acoustic characteristic analysis system 100.
2, the acoustic characteristic analysis system 100 includes an acoustic characteristic analysis device 10, a sound collection device 20, a terminal 30, a display device 40, and a sound generation device 50. The acoustic characteristic analysis device 10 is a device that analyzes a sound of a sound source 2 (see FIG. 1) heard by a sound receiver 4 (see FIG. 1) in a predetermined acoustic space 1 (see FIG. 1). Such an acoustic characteristic analysis device 10 may be configured as one computer, or may be configured as multiple computers (servers, etc.).

As shown in FIG. 2, the acoustic characteristic analysis device 10 includes a memory unit 11 and a control unit 12. The memory unit 11 includes non-volatile memory such as a ROM (Read Only Memory) or a HDD (Hard Disk Drive), and volatile memory such as a RAM (Random Access Memory) or a register. The memory unit 11 stores predetermined data in addition to programs executed by the control unit 12.

The control unit 12 is, for example, a CPU (Central Processing Unit), which reads out a program stored in the memory unit 11 and executes a predetermined process. That is, the control unit 12 outputs, as an audible signal, a received sound signal when the user simulates the experience of the sound of a predetermined sound source 2 heard in the acoustic space 1 (see FIG. 1) based on the "characteristics" of the acoustic space 1. The "characteristics" of the acoustic space 1 are the reverberation time or average sound absorption coefficient in the acoustic space 1, as will be described in detail later.

As shown in FIG. 2, the control unit 12 includes an acoustic space information setting unit 12a, a sound source information setting unit 12b, a received sound information setting unit 12c, a measurement unit 12d, and an acoustic characteristic calculation unit 12e. In addition to the above-mentioned components, the control unit 12 also includes an acoustic characteristic output unit 12f, a received sound signal calculation unit 12g, and a received sound signal output unit 12h.

The acoustic space information setting unit 12a sets acoustic space information. Such acoustic space information includes information indicating the dimensions of acoustic space 1 (see FIG. 1). If acoustic space 1 is considered to be a rectangular parallelepiped space and a specific corner is set as the origin O (0,0,0) as shown in FIG. 1, the dimensions of acoustic space 1 are set as follows. That is, if the horizontal dimension of acoustic space 1 is xa, the depth dimension is ya, and the height dimension is za, the dimensions of acoustic space 1 are expressed as (xa, ya, za). The values of the dimensions of acoustic space 1 are input by the user operating terminal 30.

The user's terminal 30 may be, for example, a computer, or a portable terminal such as a mobile phone, smartphone, tablet, or wearable device. The terminal 30 may also assume one or more of the functions of the sound collection device 20, display device 40, and sound generation device 50 shown in FIG. 2. The dimensions of the acoustic space 1 may also be measured using a distance measurement sensor such as LiDAR (Light Detection and Ranging). Such acoustic space information is stored in the memory unit 11 and is output to the acoustic characteristic calculation unit 12e and the sound reception signal calculation unit 12g.

The sound source information setting unit 12b sets sound source information. The sound source information is information about a specific sound source 2 (see FIG. 1) that is expected to be installed in the acoustic space 1 (see FIG. 1). Such sound source information includes the position of the sound source 2 in the acoustic space 1, the sound source signal, the sound pressure level of the sound source signal, as well as the distance between the measurement point of the sound pressure level and the sound source 2, the sound field at the time of measuring the sound pressure level, and the directivity coefficient of the sound source 2.

The position of sound source 2 included in the sound source information is the position of sound source 2 when it is assumed that the user places sound source 2 (a specific device) in acoustic space 1 (for example, the living room of the user's home). The position of sound source 2 in acoustic space 1 is expressed as (xs, ys, zs) with origin O shown in Figure 1 as the reference point. In the example of Figure 1, since sound source 2 exists inside acoustic space 1, xs<xa, ys<ya, zs<za. Such a position of sound source 2 is input based on the user's operation of terminal 30.

The sound source signal included in the sound source information is an audible signal from the sound source 2. Such a sound source signal is provided in advance by the manufacturer of the device (i.e., the sound source 2) based on the measurement results of the sound from the sound source 2 placed in an anechoic chamber (not shown). The sound source signal is stored in the memory unit 11 as a predetermined audio signal format (audio file format) that can be played by a sound generating device 50 such as a speaker or headphones. Representative examples of such audio signal formats include, but are not limited to, WAV, MP3, AIFF, AU, and RAW.

The sound pressure level of the sound source signal is the sound pressure level emitted from sound source 2 placed in an anechoic chamber or the like where the effects of reflections from the walls are minimized. Such sound pressure levels are extracted from the sound source signal described above and are provided in advance by the manufacturer of the device (i.e., sound source 2), etc.

The "distance" between the sound pressure level measurement point and the sound source 2 is the distance between the measurement point and the sound source 2 when the sound pressure level of the sound source 2 is measured in an anechoic chamber or the like, and is provided in advance by the manufacturer of the device (i.e., the sound source 2). Considering the stability when measuring the sound pressure level, it is desirable that the distance between the sound pressure level measurement point and the sound source 2 is 1 m or more. Also, the number of sound pressure level measurement points needs to be one or more, but it is also possible to measure the sound pressure level at multiple measurement points and include the average value of the sound pressure levels in the sound source information.

The "sound field" at the time of measuring the sound pressure level included in the sound source information is information indicating whether the acoustic space 1 (see Figure 1) is a free field or a semi-free field. Note that a free field is a sound field in which the effects of boundaries can be ignored in an isotropic and homogeneous medium. Also, a semi-free field is a sound field in which the upper half of the space above a reflective boundary surface can be considered a free field. Information specifying the sound field is input based on the user's operation of the terminal 30.

The "directivity coefficient" of the sound source 2 (see Figure 1) included in the sound source information is a value indicating the direction in which sound from the sound source 2 propagates, and is related to the position of the sound source 2 in the acoustic space 1 (see Figure 1). For example, if the sound source 2 is more than 1 m away from each wall surface, such as the side surfaces 1a and 1b, the ceiling surface 1c, and the floor surface 1d of the acoustic space 1, the directivity coefficient is set to '1'. Also, if the sound source 2 is close to one of the walls and is more than 1 m away from a wall surface other than the adjacent wall surface, the directivity coefficient is set to '2'. If the sound source 2 is close to two adjacent walls, the directivity coefficient is set to '4'. If the sound source 2 is close to three adjacent walls, the directivity coefficient is set to '8'.

The value of such a directivity coefficient may be input by the user operating the terminal 30, or may be calculated by the control unit 12 based on the position of the sound source 2 (see FIG. 1) in the acoustic space 1 (see FIG. 1). The sound source information set by the sound source information setting unit 12b is stored in the memory unit 11 and is also output to the received sound signal calculation unit 12g.

The sound receiving information setting unit 12c sets the sound receiving information. Such sound receiving information includes information indicating the position (sound receiving position) of the sound receiver 4 (see FIG. 1) in the acoustic space 1 (see FIG. 1). The sound receiving position in the acoustic space 1 is expressed as (xr, yr, zr) with the origin O shown in FIG. 1 as the reference. Note that the sound receiving position exists inside the acoustic space 1 and is different from the position (xs, ys, zs) of the sound source 2, so xr<xa, xr≠xs, yr<ya, yr≠ys, zr<za, zr≠zs.

Furthermore, it is desirable to set the sound receiving position at the center of the head or near the ears of the sound receiver 4 (see FIG. 1). This will make the sound heard when the user simulates an experience of the sound from the sound source 2 closer to the actual sound. Such sound receiving information including the position of the sound receiver 4 is input based on the user's operation of the terminal 30. The sound receiving information is stored in the memory unit 11 and is also output to the sound receiving signal calculation unit 12g.

The sound collection device 20 shown in FIG. 2 is a device that collects sound in the acoustic space 1 (see FIG. 1) as described above. Specifically, the sound collection device 20 collects a specific sound used to measure the reverberation time of the acoustic space 1. Note that "reverberation time" is a value that indicates how well a sound reverberates in the acoustic space 1. The sound used to measure the reverberation time may be a highly impulsive sound such as a paper pistol or the popping of a balloon, in addition to the sound of clapping, or an intermittent sound (or continuous sound) such as pink noise. In the following, the sound used to measure the reverberation time is referred to as the "acoustic signal for measuring reverberation time". Also, the sound source that emits the acoustic signal for measuring reverberation time is referred to as the "sound source for measuring reverberation time".

For example, if the sound signal for measuring reverberation time is a sound generated by human movement, such as clapping hands or the popping of a balloon, the human movement becomes the sound source for measuring reverberation time. Also, if the sound signal for measuring reverberation time is pink noise, a specific sound generating device (not shown) such as a speaker becomes the sound source for measuring reverberation time. When the sound collection device 20 collects the sound signal for measuring reverberation time, background noise containing various sounds such as sounds generated by each device (not shown) in the acoustic space 1 and environmental sounds propagating from the outdoors through walls and the like into the acoustic space 1 is mixed in. Even if such background noise is included, there is no particular risk of interference with the measurement of reverberation time as long as the loudness of the sound signal for measuring reverberation time is approximately 20 dB or more louder than the loudness of the background noise.

When collecting the acoustic signal for measuring reverberation time with the sound collection device 20, it is desirable that the sound source for measuring reverberation time is at least 1 m away from the sound collection device 20. It is also desirable that the sides 1a, 1b, ceiling surface 1c, and floor surface 1d of the acoustic space 1 (see FIG. 1) as well as the object 3 are at least 1 m away from the sound collection device 20. This improves stability when measuring the acoustic signal for measuring reverberation time. Data on the sound collected by the sound collection device 20 is output to the measurement unit 12d, which will be described next.

The measuring unit 12d measures the reverberation time of the acoustic space 1 based on a predetermined sound (i.e., an acoustic signal for measuring reverberation time) picked up in the acoustic space 1 by the sound pickup device 20. More specifically, the measuring unit 12d converts the acoustic signal for measuring reverberation time into a predetermined decay curve of acoustic energy (not shown). If the acoustic signal for measuring reverberation time is a highly impulsive sound (e.g., clapping), the decay curve of the acoustic energy is generated based on the inverse square integral method. If the acoustic signal for measuring reverberation time is an intermittent sound such as pink noise, the measuring unit 12d sequentially records the acoustic energy after the sound is stopped, thereby generating the decay curve of the acoustic energy. If the decay rate of acoustic energy per second is D [dB/sec], the reverberation time T [sec] is expressed by the following formula (1).

Considering the influence of indoor eigenmodes based on sound standing waves in the acoustic space 1 and variations due to the position of the sound pickup device 20, it is desirable to pick up sound at multiple positions using the sound pickup device 20. In this case, the measurement unit 12d sets the average value of the multiple reverberation times as the reverberation time of the acoustic space 1. The reverberation time value measured (calculated) by the measurement unit 12d is stored in the memory unit 11 and is also output to the acoustic characteristic calculation unit 12e.

The acoustic characteristic calculation unit 12e calculates the average sound absorption coefficient α of the acoustic space 1 based on the dimensions and reverberation time of the acoustic space 1 (see FIG. 1). Here, "average sound absorption coefficient" is a value that indicates the degree of sound absorption in the acoustic space 1. The value of the average sound absorption coefficient α is in the range of zero or more and 1 or less. For example, in an acoustic space 1 where no sound absorption occurs at all, the value of the average sound absorption coefficient α is zero. Also, when all sound is absorbed in the acoustic space 1, the value of the average sound absorption coefficient α is 1. Such an average sound absorption coefficient α is expressed by the following formula (2) based on the reverberation time T in the acoustic space 1 as well as the volume V, surface area S, and sound speed c of the acoustic space 1.

The average sound absorption coefficient α calculated by the acoustic characteristic calculation unit 12e is stored in the storage unit 11 and is also output to the acoustic characteristic output unit 12f and the received sound signal calculation unit 12g.
The acoustic characteristic output unit 12f causes the display device 40 to display the average sound absorption coefficient α calculated by the acoustic characteristic calculation unit 12e.

FIG. 3 is a front view of a smartphone 41 including a display 41a as an example of a display device.
The smartphone 41 shown in Fig. 3 is a mobile terminal of a user, and includes a display 41a as the display device 40 (see Fig. 2). The average sound absorption coefficient for each sound frequency is displayed on the display 41a in a predetermined manner, so that the user can visually grasp the average sound absorption coefficient of the acoustic space 1 (see Fig. 1).

The average sound absorption coefficient for each sound frequency may be displayed on the display 41a in a predetermined table format or graph. In addition to the average sound absorption coefficient, the reverberation time for each sound frequency may be displayed on the display 41a as information indicating the characteristics of the acoustic space 1 (see FIG. 1). In addition, information such as the average sound absorption coefficient α being "high", "medium", or "low" may be displayed on the display 41a. In addition to the display function, the smartphone 41 may also have the input function of the terminal 30 (see FIG. 2).

The sound reception signal calculation unit 12g shown in FIG. 2 calculates a sound reception signal based on the average sound absorption coefficient α calculated by the acoustic characteristic calculation unit 12e, as well as the acoustic space information, sound source information, and sound reception information described above. The sound reception signal is a signal that indicates the sound heard at the position of the sound receiver 4 (see FIG. 1) when a sound source 2 (see FIG. 1) is placed in the acoustic space 1 (see FIG. 1).

Such a received sound signal _L1 is expressed by the following formula (3) using a sound source signal _L0 emitted from the sound source 2. Note that Y included in formula (3) is the area of a sphere (in the case of a free sound field) or a hemisphere (in the case of a semi-free sound field) whose radius is the distance between the measurement point of the sound pressure level and the sound source 2, and is calculated based on the sound source information. Also, _Y0 included in formula (3) is a predetermined reference area, and Q is a directivity coefficient. Also, r included in formula (3) is the distance between the position of the sound source 2 and the position of the sound receiver 4.

Furthermore, the distance r between the position of the sound source 2 and the position of the sound receiver 4 is expressed by the following equation (4).

When a sound source 2 is placed in an acoustic space 1, a difference value ΔL between a received sound signal L ₁ at the position of a sound receiver 4 and a sound source signal L ₀ emitted from the sound source 2 is expressed by the following equation (5).

Therefore, when the sound source 2 is placed in the acoustic space 1, the received signal _L1 is a signal whose sound pressure level has changed by a difference value ΔL with respect to the sound source signal _L0 emitted from the sound source 2. This difference value ΔL is a value determined by the average sound absorption coefficient α of the acoustic space 1 as well as the distance r between the sound source 2 and the sound receiver 4. Note that, for example, an equalizer (not shown) that changes the frequency characteristics of a signal is used for the process of changing the sound source signal _L0 by a predetermined difference value ΔL. The received signal calculation unit 12g may have such an equalizer.

In addition to the received signal _L1 calculated by the received signal calculation unit 12g, a difference value ΔL between the received signal _L1 and the sound source signal _L0 is stored in the storage unit 11. In addition, the received signal _L1 calculated by the received signal calculation unit 12g is output to the received signal output unit 12h.

The received sound signal output unit 12h outputs the received sound signal _L1 calculated by the received sound signal calculation unit 12g as a predetermined audible signal. Here, the audible signal is a signal that can be heard by humans as sound. The audible signal is stored in the storage unit 11 as an acoustic signal format (audio file format) that can be reproduced by the sound generation device 50. In addition, the audible signal is output to the sound generation device 50 such as a speaker, whereby it is converted into air vibrations.

2 is, for example, a speaker, an earphone, or a headphone, and is connected to the sound signal output unit 12h by wire or wirelessly. A predetermined audible sound is generated from the sound device 50 based on the sound signal output from the sound signal output unit 12h. In this way, the sound signal _L1 is output from the sound signal output unit 12h as a predetermined audible signal, so that the user can have a simulated experience of the sound of the sound source 2 (see FIG. 1) in the acoustic space 1 (see FIG. 1).

FIG. 4 is a flowchart showing the process executed by the control unit of the acoustic characteristic analysis system (also see FIG. 1 and FIG. 2 as appropriate).
The order of the processes in steps S101 to S104 in FIG. 4 can be changed as appropriate.
In step S101, the control unit 12 sets acoustic space information by the acoustic space information setting unit 12a. As described above, the acoustic space information is information including the dimensions of the acoustic space 1, and is set based on an input operation of the terminal 30.
In step S102, the control unit 12 sets sound source information using the sound source information setting unit 12b. That is, the sound source information setting unit 12b sets sound source information including the position of the sound source 2, the sound pressure level of the sound source 2, and a sound source signal based on an input operation of the terminal 30.

In step S103, the control unit 12 sets the sound receiving information by the sound receiving information setting unit 12c. That is, the sound receiving information setting unit 12c sets the sound receiving information including the position of the sound receiver 4 based on an input operation of the terminal 30.
In step S104, the control unit 12 acquires an acoustic signal for measuring reverberation time by the sound collection device 20. For example, the acoustic signal for measuring reverberation time may be acquired in a state where a user has started a predetermined application using the terminal 30. As described above, the acoustic signal for measuring reverberation time may be a highly impulsive sound such as the sound of a user clapping his/her hands, or an intermittent sound such as pink noise.

In step S105, the control unit 12 causes the measurement unit 12d to measure the reverberation time of the acoustic space 1. That is, the control unit 12 measures the reverberation time of the acoustic space 1 based on the reverberation time measurement acoustic signal.
In step S106, the control unit 12 causes the acoustic characteristic calculation unit 12e to calculate the average sound absorption coefficient of the acoustic space 1. That is, the control unit 12 calculates the average sound absorption coefficient of the acoustic space 1 based on the dimensions and reverberation time of the acoustic space 1.

In step S107, the control unit 12 causes the acoustic characteristic output unit 12f to display the acoustic characteristic data on the display device 40. That is, the control unit 12 causes at least one of the reverberation time and the average sound absorption coefficient of the acoustic space 1 to be displayed on the display device 40. This allows the user to grasp the reverberation time and the average sound absorption coefficient of the acoustic space 1.

In step S108, the control unit 12 calculates the received sound signal by the sound signal calculation unit 12g. That is, the control unit 12 calculates the received sound signal based on the acoustic space information, the sound source information, the sound reception information, and the average sound absorption coefficient.
In step S109, the control unit 12 outputs the received sound signal to the sound generation device 50 via the received sound signal output unit 12h. This allows the user to virtually experience the sound that would be heard if the sound source 2 were placed in the acoustic space 1.

＜Effects＞
According to the first embodiment, a user can hear the operation sound of a specific device when it is used in a usage environment (i.e., acoustic space 1) without going to a home appliance retailer or the like. The received sound signal includes sound source information and sound reception information in addition to the dimensions of the acoustic space 1. Therefore, the user can simulate an operation sound close to the operation sound when the device is actually used in the acoustic space 1. In addition, the device can be used in the development stage, where a designer can simulate an operation sound of the device in a specific usage environment and then reflect the result in the design.

Second Embodiment
The second embodiment differs from the first embodiment in that there is no particular need to provide a sound collection device 20 (see FIG. 2) or a measurement unit 12d (see FIG. 2). The second embodiment also differs from the first embodiment in that the value of the average sound absorption coefficient is input from the terminal 30 (see FIG. 5) to the acoustic characteristic calculation unit 12e (see FIG. 5). The rest of the second embodiment is the same as the first embodiment. Therefore, only the parts that differ from the first embodiment will be described, and the description of the overlapping parts will be omitted.

FIG. 5 is a functional block diagram of an acoustic characteristic analysis system 100A according to the second embodiment.
5, the acoustic characteristic analysis system 100A includes an acoustic characteristic analysis device 10A, a terminal 30, a display device 40, and a sound generation device 50. The control unit 12A of the acoustic characteristic analysis device 10A includes an acoustic space information setting unit 12Aa, a sound source information setting unit 12b, and a received sound information setting unit 12c, as well as an acoustic characteristic calculation unit 12Ae, an acoustic characteristic output unit 12f, a received sound signal calculation unit 12g, and a received sound signal output unit 12h.

The acoustic space information setting unit 12Aa has a function of setting the average sound absorption coefficient of the acoustic space 1 (see FIG. 1) in addition to the dimensions of the acoustic space 1. It is assumed that the average sound absorption coefficient of the acoustic space 1 is known based on past measurements, etc. Such an average sound absorption coefficient value may be input by operating the terminal 30, or may be a value of the average sound absorption coefficient already stored in the memory unit 11.

The average sound absorption coefficient set by the acoustic space information setting unit 12Aa is output to the sound reception signal calculation unit 12g via the acoustic characteristic calculation unit 12Ae. Since the average sound absorption coefficient of the acoustic space 1 has already been given, there is no need for the acoustic characteristic calculation unit 12Ae to calculate the average sound absorption coefficient. The remaining components of the control unit 12A shown in FIG. 2 are the same as those in the first embodiment, and therefore will not be described.

＜Effects＞
According to the second embodiment, when the average sound absorption coefficient has already been acquired, it is no longer necessary to record an acoustic signal for measuring the reverberation time (for example, the sound of a user clapping his hands) again in the acoustic space 1 (see FIG. 1 ), thereby improving convenience for the user.

<Modification of the Second Embodiment>
In the second embodiment, a case has been described in which the value of the average sound absorption coefficient is input by the user operating the terminal 30 (see FIG. 5), but the reverberation time of the acoustic space 1 (see FIG. 1) may be input instead of the average sound absorption coefficient. It is assumed that the reverberation time of the acoustic space 1 is known based on past measurements, etc. In this case, the acoustic space information setting unit 12Aa (see FIG. 5) sets the reverberation time in the acoustic space 1 and outputs the value of this reverberation time to the acoustic characteristic calculation unit 12Ae.

The acoustic characteristic calculation unit 12Ae calculates the average sound absorption coefficient of the acoustic space 1 based on the reverberation time. The average sound absorption coefficient calculated by the acoustic characteristic calculation unit 12Ae is output to the received sound signal calculation unit 12g. When a value of the reverberation time (or the average sound absorption coefficient) is input by operating the terminal 30, the received sound signal calculation unit 12g (i.e., the control unit 12A) uses the value when calculating the received sound signal. With this configuration, the same effect as in the second embodiment can be achieved.

Third Embodiment
The third embodiment differs from the second embodiment in that an acoustic space 1B (see FIG. 6) is constructed as a virtual space, and when a predetermined sound source (e.g., the vacuum cleaner 60 in FIG. 6) is placed in the acoustic space 1B, the user experiences a simulated sound heard by a character 5 (see FIG. 6) in the virtual space. Note that other aspects (such as the configuration of the acoustic characteristic analysis system 100A: see FIG. 5) are the same as those of the second embodiment. Therefore, only the parts that differ from the second embodiment will be described, and the explanation of the overlapping parts will be omitted.

FIG. 6 is an explanatory diagram showing a situation in which a predetermined character 5 is using a vacuum cleaner 60, which is a sound source, in the acoustic characteristic analysis system according to the third embodiment.
The acoustic space 1B shown in Fig. 6 is a three-dimensional virtual space (e.g., metaverse) constructed by a computer such as a server (not shown). Such a virtual space may be used for virtual live shows, online games, and EC (Electronic Commerce) which is a virtual shop. In addition, the image of the acoustic space 1B may be displayed on a mobile terminal such as a smartphone or tablet, or may be displayed on a head-mounted display, smart glasses, or smart contact lenses.

FIG. 6 shows an example in which a specific character 5 is using a vacuum cleaner 60 in a living room, which is an acoustic space 1B. The character 5 is, for example, an avatar that represents a user, but may also be another specific character.

Then, the control unit 12A (see FIG. 5) causes the display device 40 (see FIG. 5) to display an image corresponding to the sound source (vacuum cleaner 60 in the example of FIG. 6), and also causes a predetermined character 5 to be displayed on the display device 40. The control unit 12A also sets the position of the sound receiver hearing the sound of the sound source (vacuum cleaner 60 in the example of FIG. 6) in the acoustic space 1B as the position of the character 5. This allows the user to hear the sound of the sound source heard at the position of the character 5 through the sound generation device 50 (see FIG. 5).

The vacuum cleaner 60 shown in FIG. 6 is a sound source selected by the user through operation of the terminal 30 (see FIG. 5). The type of device corresponding to the sound source is not limited to the vacuum cleaner 60, but may be other home appliances such as an air conditioner or a washing machine, or may be a specified device other than a home appliance. Based on the user's operation of the terminal 30 (see FIG. 5), the character 5 can move in the acoustic space 1B, and the type and position of the sound source (vacuum cleaner 60 in the example of FIG. 6) can be changed.

The processing performed by the control unit 12A (see FIG. 5) is the same as in the second embodiment. That is, the control unit 12A outputs, as an audible signal, a received sound signal when the user simulates the experience of the sound of a specific sound source (vacuum cleaner 60 in the example of FIG. 6) heard in the acoustic space, based on the characteristics of the acoustic space 1B, which is a virtual space. Specifically, the control unit 12A outputs a specific received sound signal based on the average sound absorption coefficient or reverberation time value indicating the characteristics of the acoustic space 1B.

The average sound absorption coefficient or reverberation time of acoustic space 1B may be set based on the operation of terminal 30 (see FIG. 5), or a value previously stored in memory unit 11 (see FIG. 5) may be used. For example, when acoustic space 1B having the same dimensions as a specific acoustic space that actually exists is set in a virtual space, and the average sound absorption coefficient or reverberation time of the real acoustic space is known, these values may be used as the average sound absorption coefficient or reverberation time of acoustic space 1B in the virtual space.

Furthermore, it is preferable that the control unit 12A (see FIG. 5) changes the received sound signal in response to a change in the position of the character 5 in the acoustic space 1B or a change in the position of the sound source (vacuum cleaner 60 in the example of FIG. 6). This makes the sound that the user hears through the sound generation device 50 (see FIG. 5) of the operating sound of the vacuum cleaner 60 more realistic.

＜Effects＞
According to the third embodiment, when the acoustic space 1B is set as a virtual space, the user can hear the sound coming from the sound source at the position of a predetermined character 5. This can enhance the sense of reality when the user experiences the sound of the sound source in the virtual space in a simulated manner.

Fourth Embodiment
The fourth embodiment differs from the first embodiment in that a plurality of conditions, such as the dimensions of the acoustic space 1 (see FIG. 1), the type and position of the sound source 2 (see FIG. 1), and the position of the sound receiver 4 (see FIG. 1), can be set and compared. Note that other aspects (such as the configuration of the acoustic characteristic analysis system 100: see FIG. 2) are the same as those of the first embodiment. Therefore, only the parts that differ from the first embodiment will be described, and the explanation of the overlapping parts will be omitted.

The fourth embodiment will be described with reference to FIGS.
The acoustic space information setting unit 12a shown in Fig. 2 sets acoustic space information including dimensions of the acoustic space 1. Such acoustic space information may be information of a specific acoustic space 1, or may be information of multiple acoustic spaces 1 with different dimensions or acoustic characteristics (average sound absorption coefficient, etc.). For example, the operating sound of a vacuum cleaner, which is the sound source 2, often sounds different when the user uses the vacuum cleaner in the living room and when the user uses the vacuum cleaner in the bedroom. Therefore, when simulating the experience of the sound of the sound source 2 in multiple acoustic spaces 1 with different dimensions and acoustic characteristics, the user inputs the acoustic space information of each of the multiple acoustic spaces 1.

The sound source information setting unit 12b shown in FIG. 2 sets sound source information related to the sound source 2. Such sound source information may be information related to one specific type of sound source 2, or information related to multiple types of sound sources 2. Furthermore, multiple pieces of sound source information may be set for a specific sound source 2 when its position is different. For example, the sound source 2, which is a vacuum cleaner, may sound differently at a specific sound receiving position when the vacuum cleaner is operated in the center of the living room than when the vacuum cleaner is operated near a corner of the living room. Therefore, when simulating the experience of the sound of a specific sound source 2 of a different type or position, the user inputs sound source information related to that sound source 2.

The sound receiving information setting unit 12c shown in FIG. 2 sets sound receiving information including the position of the sound receiver 4. The position information of the sound receiver 4 included in the sound receiving information may be a single predetermined sound receiving position in the acoustic space 1, or may be multiple sound receiving positions. For example, the way the sound of the sound source 2 is heard may differ between when the sound receiver 4 is in the center of the living room and when the sound receiver 4 is near a corner of the living room. Therefore, when simulating the experience of hearing at multiple sound receiving positions, the user inputs sound receiving information including each sound receiving position.

The acoustic characteristic calculation unit 12e shown in FIG. 2 calculates the average sound absorption coefficient of the acoustic space 1 based on the reverberation time of the acoustic space 1. When the dimensions of multiple acoustic spaces 1 are set in the acoustic space information setting unit 12a, multiple reverberation times are measured so as to correspond to the acoustic signal for measuring the reverberation time of each acoustic space 1. Furthermore, multiple average sound absorption coefficients are calculated so as to correspond to each reverberation time. The multiple average sound absorption coefficients calculated by the acoustic characteristic calculation unit 12e are stored in the memory unit 11 in correspondence with the multiple acoustic spaces 1, and are also output to the acoustic characteristic output unit 12f and the sound reception signal calculation unit 12g.

The received sound signal calculation unit 12g shown in FIG. 2 calculates the received sound signal based on the average sound absorption coefficient, etc. When at least one of the positions of the sound source 2 and the position of the sound receiver 4 is set multiple times, the received sound signal calculation unit 12g calculates the distance r between the sound source 2 and the sound receiver 4 in correspondence with the combination of the position of the sound source 2 and the position of the sound receiver 4. As in the first embodiment, the value of this distance r is used to calculate the received sound signal. The received sound signal output unit 12h shown in FIG. 2 outputs the received sound signal calculated by the received sound signal calculation unit 12g to the sound generation device 50 as an audible signal.

If at least one piece of information among the dimensions of acoustic space 1, the characteristics of acoustic space 1 (average sound absorption coefficient or reverberation time), the position of sound source 2, the type of sound source 2, and the position of receiver 4 in acoustic space 1 is changed by operating terminal 30, it is preferable that control unit 12 change the received sound signal based on the changed information. This allows the user to compare how the sound sounds when using a vacuum cleaner in the living room and when using the vacuum cleaner in the bedroom, for example. The user can also compare how the sound sounds when the position of the vacuum cleaner or the position of receiver 4 is changed.

＜Effects＞
According to the fourth embodiment, the user can realize the difference in how the sound sounds when the positions of the sound source 2 and the receiver 4 are changed, in addition to the dimensions and acoustic characteristics of the acoustic space 1, and can use this information as a basis for making a decision when the user purchases a device that is the sound source 2.

Fifth embodiment
The fifth embodiment differs from the first embodiment in that a received sound signal is generated based on the head-related transfer function of the sound receiver 4 (see FIG. 1). Other aspects (such as the configuration of the acoustic characteristic analysis system 100: see FIG. 2) are the same as those of the first embodiment. Therefore, only the parts that are different from the first embodiment will be described, and the description of the overlapping parts will be omitted.

The fourth embodiment will be described with reference to FIGS.
The sound receiving information setting unit 12c shown in Fig. 2 sets the position of the sound receiver 4 (see Fig. 1) as well as the head transfer function of the sound receiver 4. The head transfer function is a predetermined function that indicates the characteristics of the sound reflected or diffracted by the head, body, and pinna of the sound receiver 4 (see Fig. 1) until it reaches the ear (entrance of the ear canal) of the sound receiver 4. For example, when a sound arrives from the front of the sound receiver 4, the head transfer function often has a predetermined flat characteristic at low frequencies below 1.6 kHz. In this case, the incident sound wave that reaches the ear of the sound receiver 4 rarely becomes stronger or weaker than the actual sound.

On the other hand, at high frequencies above 1.6 kHz, the characteristics of the head-related transfer function are often not flat due to the effects of sound reflection and diffraction at the head, body, and pinna of the receiver 4. In this case, the incident sound waves that reach the ears of the receiver 4 are often stronger or weaker than the actual sound. Therefore, when a sound with a high sound pressure level at high frequencies is set as the sound source 2 (see Figure 1), the sound heard by the user is more likely to be affected by the head-related transfer function. By including such a head-related transfer function in the sound reception information, the user can simulate an experience of sound that reflects the effects of reflection and diffraction at the head, body, and pinna of the receiver 4.

For example, a predetermined value indicating a head-related transfer function may be input based on an operation of the terminal 30. Also, a standard predetermined head-related transfer function may be used as appropriate. The received sound information including the head-related transfer function is output from the received sound information setting unit 12c to the received sound signal calculation unit 12g.

2 adds a predetermined head-related transfer function to the received signal L1 of the formula (3) described in the first embodiment when calculating the received signal _L1 of the sound heard at the position of the receiver 4. This calculates a new received signal _L1 that reflects the influence of reflection and diffraction at the head, body, and pinna of the receiver 4. That is, the control unit 12 calculates the received signal _L1 based on the acoustic space information, sound source information, sound reception information, average sound absorption coefficient, and the head- _related transfer function of the receiver.

When a user wants to simulate a sound experience, it is desirable to use a sound generation device 50 (see FIG. 2) such as headphones or earphones that emit sound from near the user's ear (specifically, the entrance to the ear canal). This eliminates the need to consider the head-related transfer function from the sound generation device 50 to the user's ear.

＜Effects＞
According to the fifth embodiment, by including a head-related transfer function in the sound reception information, it is possible to enhance the sense of reality when the user virtually experiences the sound of the sound source 2 in the acoustic space 1.

Sixth Embodiment
In the sixth embodiment, a case will be described in which a sound source 2 (see FIG. 7) is provided in one of two spaces adjacent to each other via a partition wall 6 (see FIG. 7), and a sound receiver 4 (see FIG. 7) is present in the other space. The configuration of the acoustic characteristic analysis system 100 (see FIG. 2) is the same as that of the first embodiment. Therefore, only the parts different from the first embodiment will be described, and the explanation of the overlapping parts will be omitted.

FIG. 7 is an explanatory diagram of an acoustic space that is a target of the acoustic characteristic analysis system according to the sixth embodiment.
The sound source space 1C shown in FIG. 7 is an acoustic space in which a sound source 2 is provided. The sound receiving space 1D is an acoustic space in which a sound receiver 4 exists. As shown in FIG. 7, the sound source space 1C and the sound receiving space 1D are adjacent to each other via a partition wall 6. In the sound source space 1C, a certain object 31 such as a desk, a chair, or a shelf is placed, and a window and a door are provided, although not shown. The same is true for the sound receiving space 1D. The partition wall 6 is a wall that separates the sound source space 1C and the sound receiving space 1D. As shown in FIG. 7, the partition wall 6 forms a part of the side surface of the sound source space 1C and also forms a part of the side surface of the sound receiving space 1D.

The processing of the acoustic characteristic analysis system 100 will be explained using FIG. 2 (also see FIG. 7 as appropriate). The acoustic space information setting unit 12a shown in FIG. 2 sets acoustic space information including the dimensions of the sound source space 1C and the sound receiving space 1D and the sound transmission loss of the partition wall 6 based on the operation of the terminal 30. The sound transmission loss is a value indicating the level of the sound insulation performance of the partition wall 6. The higher the sound insulation performance of the partition wall 6, the larger the value of the sound transmission loss.

The sound source information setting unit 12b shown in FIG. 2 sets predetermined sound source information. Such sound source information includes information to set one of two acoustic spaces adjacent to each other via a partition wall 6 as sound source space 1C, as well as the sound source signal of sound source 2, the sound pressure level of the sound source signal, the distance between the sound pressure level measurement point and sound source 2, and the directivity coefficient of sound source 2.

2 sets the sound receiving information. Such sound receiving information includes information to set one of two acoustic spaces adjacent to each other via the partition wall 6 as the sound receiving space 1D.
A sound collecting device 21 shown in Fig. 7 measures a reverberation time measuring acoustic signal (sound of a user clapping hands or pink noise) in a sound source space 1C. A sound collecting device 22 shown in Fig. 7 measures a reverberation time measuring acoustic signal in a sound receiving space 1D.

The measurement unit 12d shown in FIG. 2 measures the reverberation time of the sound source space 1C and the sound receiving space 1D based on the reverberation time measurement acoustic signals measured in each of the sound source space 1C and the sound receiving space 1D.
2 calculates the average sound absorption coefficient of the sound source space 1C and the sound receiving space 1D based on the reverberation times of the sound source space 1C and the sound receiving space 1D. The average sound absorption coefficient is calculated using the formula (2) described in the first embodiment.

The sound receiving signal calculation unit 12g shown in FIG. 2 calculates a sound receiving signal of an average sound that is heard in the sound receiving space 1D through the partition wall 6 when the sound emitted from the sound source 2 is heard in the sound receiving space 1D based on the average sound absorption coefficients of the sound source space 1C and the sound receiving space 1D, as well as the acoustic space information, sound source information, and sound receiving information described above. The average sound pressure level L _B of the sound receiving space 1D is expressed by the following formula (6). Here, L _A included in formula (6) is the average sound pressure level of the sound source space 1C. Furthermore, TL included in formula (6) is the sound transmission loss of the partition wall 6, and S is the surface area of the partition wall 6. Furthermore, S _B included in formula (6) is the surface area of the sound receiving space 1D, and α _B is the average sound absorption coefficient of the sound receiving space 1D.

Moreover, the average sound pressure level L _A of the sound source space 1C when the acoustic power level of the sound source 2 is L _W is expressed by the following formula (7). Note that L ₀ included in formula (7) is the sound source signal emitted from the sound source 2, and Y is the area of a sphere (in the case of a free sound field) or a hemisphere (in the case of a semi-free sound field) whose radius is the distance between the measurement point of the sound pressure level and the sound source 2. Furthermore, Y ₀ included in formula (7) is a predetermined reference area, and A _A is the transmission and absorption area of the sound source space 1C.

By substituting formula (7) into formula (6), the average sound pressure level L _B of the sound receiving space 1D is expressed by the following formula (8): In formula (8), S _A is the surface area of the sound source space 1C, and α _A is the average sound absorption coefficient of the sound source space 1C.

Therefore, the difference value (L _B −L ₀ ) between the sound pressure level L ₀ of the sound source signal and the average sound pressure level L _B of the sound receiving space 1D is expressed by the following equation (9).

When the partition 6 (see FIG. 7) is composed of n parts with different transmittances τ, the sound transmission loss of the partition 6 (also called the total sound transmission loss) is expressed by the following formula (10). Such total sound transmission loss is particularly effective when the partition 6 contains parts made of different materials, for example, when part of the partition 6 is made of glass and other parts are made of resin.

In this case, the above formula (6) is replaced with the following formula (11).

Therefore, the difference value ΔL between the sound pressure level L ₀ of the sound source signal and the average sound pressure level L _B of the sound receiving space 1D is expressed by the following formula (12).

From formula (12), the following can be said. That is, when sound emitted from the sound source 2 in the sound source space 1C (see FIG. 7) propagates to the sound receiving space 1D through the partition wall 6, the average received sound signal L _B heard in the sound receiving space 1D becomes a signal that has changed by a difference value ΔL with respect to the sound source signal L _0. For example, an equalizer (not shown) capable of changing the frequency characteristics of a signal is used for the process of changing the sound source signal L ₀ by the difference value ΔL. Such an equalizer may be included in the received sound signal calculation unit 12g (see FIG. 2).

The received sound signal L _B calculated by the received sound signal calculation unit 12g is output to the received sound signal output unit 12h (see FIG. 2). A predetermined received sound signal is then output as an audible signal from the received sound signal output unit 12h to the sound generation device 50 (see FIG. 2). In this manner, when it is assumed that the sound source 2 exists in one of the two acoustic spaces (sound source space 1C and sound receiving space 1D) adjacent to each other via the partition 6, and the sound receiver 4 exists in the other, the control unit 12 (see FIG. 2) calculates the received sound signal based on information including the sound transmission loss of the partition 6.

If the sound transmission loss of the partition wall 6 is changed by operating the terminal 30, the control unit 12 may change the received sound signal in accordance with the change in sound transmission loss. This allows the user to compare the difference in the sound heard by the receiver 4 when, for example, a window (not shown) in the partition wall 6 is closed and when the window is open.

＜Effects＞
According to the sixth embodiment, when a sound source space 1C in which a sound source 2 is provided and a sound receiving space 1D in which a sound receiver 4 exists are adjacent to each other via a partition wall 6, a user can simulate an experience of a sound heard by the sound receiver 4. For example, when a user uses a vacuum cleaner in a living room of a house, the user can confirm how the sound sounds to a person in a bedroom next to the living room. Also, when a user uses a vacuum cleaner in a room, the user can confirm how the sound sounds to a person living in the next room.

Seventh embodiment
In the seventh embodiment, a case will be described in which a sound source 2 (see FIG. 8) is provided in an open space such as outdoors, and a sound receiver 4 (see FIG. 8) is present in a sound receiving space 1F separated from the open space by a partition wall 7 (see FIG. 8). The configuration of the acoustic characteristic analysis system 100 (see FIG. 2) is the same as that of the first embodiment. Therefore, the parts different from the first embodiment will be described, and the explanation of the overlapping parts will be omitted.

FIG. 8 is an explanatory diagram of an acoustic space that is a target of the acoustic characteristic analysis system according to the seventh embodiment.
The sound source space 1E shown in Fig. 8 is an open space such as outdoors where the sound source 2 is installed. An example of such an open space is an urban area, but is not limited to this. The sound receiving space 1F is an acoustic space such as a room where a sound receiver 4 exists, and is separated from the sound source space 1E such as outdoors by a partition wall 7. The surface of the partition wall 7 forms a part of the side surface of the sound receiving space 1F.

The processing of the acoustic characteristic analysis system 100 will be described with reference to FIG. 2 (also see FIG. 8 as appropriate).
The acoustic space information setting unit 12a shown in Fig. 2 sets acoustic space information based on the operation of the terminal 30. Such acoustic space information includes information indicating that the sound source space 1E is an open space, as well as the dimensions of the sound receiving space 1F and the sound transmission loss of the partition wall 7. Note that the sound transmittance τ of the partition wall 7 does not need to be uniform, and the partition wall 7 may be composed of n types of parts with different sound transmittances τ. In this case, the sound transmission loss of the partition wall 7 (total sound transmission loss) is expressed by equation (10) described in the sixth embodiment.

The sound source information setting unit 12b shown in FIG. 2 sets the sound source information. In addition to the position of the sound source 2 and the sound source signal, such sound source information includes the sound pressure level of the sound source signal, the distance between the sound pressure level measurement point and the sound source 2, and the directivity coefficient of the sound source 2. As shown in FIG. 8, if a predetermined position of the ground 8 in the sound source space 1E is the origin O (0,0,0), the position of the sound source 2 is expressed as (xp,yp,zp). Regarding the directivity coefficient of the sound source 2, if the sound source 2 is 1m or more away from the ground 8 in an open space such as outdoors, the directivity coefficient of the sound source 2 is set to '1'. Also, if the sound source 2 is close to the ground 8 and is 1m or more away from other reflecting surfaces, the directivity coefficient of the sound source 2 is set to '2'.

The sound receiving information setting unit 12c shown in FIG. 2 sets the sound receiving information. Such sound receiving information includes information to set one of the two acoustic spaces as the sound receiving space 1F, as well as the position of the partition wall 7 and the value of the sound transmission loss of the partition wall 7. As shown in FIG. 8, the position of the partition wall 7 is represented by (xq, yq, zq). However, xp ≠ xq, yp ≠ yq, zp ≠ zq.

The sound collection device 20 shown in FIG. 8 collects an acoustic signal for measuring reverberation time in the sound receiving space 1F (e.g., the sound of a user clapping hands or pink noise). The measurement unit 12d shown in FIG. 2 measures the reverberation time of the sound receiving space 1F based on the acoustic signal for measuring reverberation time collected by the sound collection device 20. Note that the equation (1) described in the first embodiment is used to calculate the reverberation time. The value of the reverberation time measured by the measurement unit 12d is output to the acoustic characteristic calculation unit 12e.

The acoustic characteristic calculation unit 12e shown in FIG. 2 calculates the average sound absorption coefficient of the sound receiving space 1F based on the reverberation time. The average sound absorption coefficient is calculated using the formula (2) described in the first embodiment. The value of the average sound absorption coefficient calculated by the acoustic characteristic calculation unit 12e is output to the acoustic characteristic output unit 12f and the received sound signal calculation unit 12g.

The sound receiving signal calculation unit 12g calculates an average sound receiving signal of the sound emitted from the sound source 2 and heard in the sound receiving space 1F based on the average sound absorption coefficient of the sound receiving space 1F, as well as the acoustic space information, the sound source information, and the sound receiving information. Specifically, the average sound pressure level L _B of the sound receiving space 1F is expressed by the following formula (13). Note that L _C included in formula (13) is the sound pressure level of the sound incident on the partition wall 7 from the sound source space 1E. Also, TL included in formula (13) is the sound transmission loss in the partition wall 7, and S is the surface area of the partition wall 7. Also, S _B included in formula (13) is the surface area of the sound receiving space 1F, and α _B is the average sound absorption coefficient of the sound receiving space 1F.

When the acoustic power level of the sound source 2 is _LW , the sound pressure level L _C of the sound incident on the partition wall 7 from the sound source space 1E is expressed by the following equation (14).

Included in equation (14) is _r1 , which is the distance between the sound source 2 and the partition wall 7, and is expressed by the following equation (15).

The central position of the partition wall 7 may be set as the representative position of the partition wall 7. In this case, the average sound pressure level L _B in the sound receiving space 1F is expressed by the following formula (16).

Therefore, the difference value _ΔL1 between the sound pressure level _L0 of the sound source signal and the average sound pressure level _LB of the sound receiving space 1F is expressed by the following equation (17).

From formula (17), the following can be said. That is, when sound emitted from the sound source 2 propagates through the partition wall 7 to the sound receiving space 1F, the average received sound signal L _B of the sound _heard in the sound receiving space 1F becomes a signal that has changed by a difference value ΔL ₁ with respect to the sound source signal L _0. For example, an equalizer (not shown) capable of changing the frequency characteristics of a signal is used for the process of changing the sound source signal L 0 by the difference value ΔL _1. Such an equalizer may be included in the received sound signal calculation unit 12g (see FIG. 2).

The received sound signal L _B calculated by the received sound signal calculation unit 12g is output to the received sound signal output unit 12h (see FIG. 2). A predetermined received sound signal is then output as an audible signal from the received sound signal output unit 12h to the sound generation device 50 (see FIG. 2). In this manner, the control unit 12 calculates the received sound signal based on information including the sound transmission loss of the partition wall 7 when it is assumed that the receiver 4 is present in the sound receiving space 1F (acoustic space) separated by the partition wall 7 from the sound source space 1E (open space) in which the sound source 2 is provided.

If the sound transmission loss of the partition wall 7 is changed by operating the terminal 30, the control unit 12 may change the received sound signal in accordance with the change in sound transmission loss. This allows the user to confirm, for example, the difference in how sound is heard when a window (not shown) in the partition wall 7 is opened or closed.

＜Effects＞
According to the seventh embodiment, when the sound source 2 is in a sound receiving space 1F separated by a partition wall 7 from an open space such as outdoors and the like, the user can simulate the experience of the sound heard by the sound receiver 4. In addition, when flying an airplane, helicopter, drone, or the like, or when operating a construction machine such as an excavator, the user can simulate the experience of how the sound is heard in the sound receiving space 1F. In addition, during the development stage of the equipment, the designer can simulate the experience of the operating sound of the equipment in a specified usage environment, and then the result can be reflected in the design.

<<Variations>>
Although the acoustic characteristic analysis system 100 according to the present disclosure has been described in each embodiment, the present disclosure is not limited to these descriptions and various modifications can be made.
For example, in the first embodiment, the control unit 12 of the acoustic characteristic analysis device 10 (see FIG. 2) is described as having each component such as the acoustic space information setting unit 12a, but this is not limited to the above. That is, the terminal 30 may take on some or all of the functions of the acoustic space information setting unit 12a, etc., provided in the control unit 12. The same can be said about the second to seventh embodiments.

In the first embodiment, the sound collection device 20 (see FIG. 2) is separate from the acoustic characteristic analysis device 10 (see FIG. 2), but this is not limited to the above. In other words, the sound collection device 20 may be included in the acoustic characteristic analysis device 10. The same can be said about the fourth to seventh embodiments.

In addition, in each embodiment, the average sound absorption coefficient and reverberation time of the acoustic space 1 are displayed on the display device 40, but other data may be displayed. For example, the waveform of the sound received at the position of the sound receiver 4 (such as changes in sound pressure level from moment to moment) may be displayed on the display device 40. In this case, the waveform of the sound source signal may also be displayed on one screen in synchronization with the received sound signal.

Furthermore, the acoustic characteristic calculation unit 12e (i.e., the control unit 12) may calculate the voice clarity based on the sound collected in the acoustic space 1 by the sound collection device 20, the acoustic space information, the sound source information, and the sound reception information. Note that the voice clarity is a value indicating the degree of ease of hearing the voice. In this case, in addition to the acoustic space information, the sound source information and the sound reception information are also input to the acoustic characteristic calculation unit 12e. Furthermore, the voice clarity may be displayed on the display device 40 together with information indicating the characteristics of the acoustic space 1 (average sound absorption coefficient and reverberation time). This allows the user to understand the degree of ease of conversation in the acoustic space 1. Note that information such as "high", "medium", or "low" voice clarity may be displayed on the display device 40.

In the sixth embodiment, the partition 6 (see FIG. 7) constitutes part of the side of the sound source space 1C and also constitutes part of the side of the sound receiving space 1D, but this is not limited to the above. For example, the sixth embodiment can also be applied to a case where a specific partition (not shown) constitutes the ceiling surface (or floor surface) of the sound source space and also constitutes the floor surface (or ceiling surface) of the sound receiving space. The same can be said about the seventh embodiment.

In addition, in each embodiment, the sound source 2 is a specific device, but this is not limiting. For example, each embodiment can be applied to a case where the sound source 2 is a human voice or an animal cry.
Moreover, each embodiment can also be applied to the analysis of noise caused by the operation of equipment (i.e., the sound source 2). For example, based on the seventh embodiment, it is also possible to analyze noise generated when a construction machine or the like is operated outdoors.

In addition, each embodiment can be appropriately combined. For example, in a case where the sound source space 1C and the sound receiving space 1D are adjacent to each other via a partition wall 6 (sixth embodiment), the control unit 12 may calculate a sound receiving signal based on an average sound absorption coefficient or the like input by operating the terminal 30 (second embodiment).
In addition, for example, the third embodiment and the seventh embodiment may be combined, and in a virtual space (third embodiment), the control unit 12 may calculate a sound receiving signal indicating how sound is heard in a sound receiving space 1F separated from an open space by a partition 7 (seventh embodiment).

The third and sixth embodiments may also be combined to form the following configuration. That is, in a virtual space, when a specific character (sound receiver) exists in a sound source space in which a sound source 2 is provided, and when a character (sound receiver) exists in a sound receiving space adjacent to the sound source space via a partition wall 6, and when switching from one to the other by operating the terminal 30, the control unit 12 may change the position of the character on the display screen and change the sound receiving signal of the sound heard at the character's position. With this configuration, the sound receiving signal changes in accordance with the change in the character's position, thereby enhancing the sense of realism when the user has a specific simulated experience in the virtual space.

Furthermore, the third, sixth, and seventh embodiments may be combined to form the following configuration. That is, in a virtual space, when a predetermined character (sound receiver) exists in a sound receiving space adjacent to the sound source space in which the sound source 2 is provided via a partition wall 6, and when a character (sound receiver) exists in a sound receiving space separated by a partition wall 7 from an open space in which the sound source 2 is provided (outdoors, etc.), and when switching from one to the other by operating the terminal 30, the control unit 12 may change the position of the character on the display screen and change the sound receiving signal. With such a configuration, the sense of realism when the user has a predetermined simulated experience in the virtual space can be enhanced.

The third and seventh embodiments may also be combined to form the following configuration. That is, when a specific character (sound receiver) exists in a sound source space in which the sound source 2 is provided in a virtual space, and when a character (sound receiver) exists in a sound receiving space separated by a partition wall 7 from an open space in which the sound source 2 is provided (outdoors, etc.), and when switching is performed from one to the other by operating the terminal 30, the control unit 12 may change the position of the character on the display screen and change the sound receiving signal. With such a configuration, the sense of realism when the user has a specific simulated experience in the virtual space can also be enhanced.

At least a part of the calculation results of each component such as the acoustic space information setting section 12a of the control section 12 (see FIG. 2) may be stored in an information recording medium such as a hard disk drive or a removable disk.
Furthermore, the processes (such as the acoustic characteristic analysis method) executed by the acoustic characteristic analysis system 100 may be executed as a predetermined program of a computer. The program may be provided via a communication line, or may be written onto a recording medium such as a CD-ROM and distributed.

In addition, each embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the configurations described. Furthermore, it is possible to add, delete, or replace some of the configurations of the embodiments with other configurations. Furthermore, the mechanisms and configurations described above are those that are considered necessary for explanation, and do not necessarily represent all of the mechanisms and configurations of the product.

1. Acoustic space (real space)
1B Acoustic space (virtual space)
1C Sound source space (acoustic space)
1D Sound receiving space (acoustic space)
1E Sound source space (acoustic space, open space)
1F Sound receiving space (acoustic space)
2 Sound source 3 Object 4 Sound receiver 5 Character 6, 7 Partition 10, 10A Acoustic characteristic analysis device 11 Memory unit 12, 12A Control unit 12a, 12Aa Acoustic space information setting unit 12b Sound source information setting unit 12c Sound reception information setting unit 12d Measurement unit 12e, 12Ae Acoustic characteristic calculation unit 12f Acoustic characteristic output unit 12g Sound reception signal calculation unit 12h Sound reception signal output unit 20, 21, 22 Sound collection device 30 Terminal 40 Display device 50 Sound generation device 60 Vacuum cleaner (sound source)
41 Smartphone 41a Display (display device)
100, 100A Acoustic Characteristic Analysis System

Claims (15)

1. An acoustic characteristic analysis system that includes a control unit that outputs, as an audible signal, a received signal that is received when a user simulates the experience of hearing a specific sound source in an acoustic space, which may be a real space or a virtual space, based on the characteristics of the acoustic space.
2. The acoustic characteristic analysis system according to claim 1 , wherein the characteristic is a reverberation time or an average sound absorption coefficient in the acoustic space.
3. 3. The acoustic characteristic analysis system according to claim 2, wherein the control unit measures the reverberation time based on a predetermined sound picked up in the acoustic space by a sound pickup device, and calculates the average sound absorption coefficient based on a dimension of the acoustic space and the reverberation time.
4. The acoustic characteristic analysis system according to claim 2 , wherein the control unit causes a display device to display at least one of the reverberation time and the average sound absorption coefficient.
5. The control unit is
   an acoustic space information setting unit that sets acoustic space information including dimensions of the acoustic space;
   a sound source information setting unit that sets sound source information including a position of the sound source, a sound pressure level of the sound source, and a sound source signal;
   a sound receiving information setting unit that sets sound receiving information including a position of a sound receiver in the acoustic space;
   The acoustic characteristic analyzing system according to claim 2 , further comprising a sound reception signal calculation unit that calculates the sound reception signal based on the acoustic space information, the sound source information, the sound reception information, and the average sound absorption coefficient.
6. 6. The acoustic characteristic analysis system according to claim 5, wherein when a value of the average sound absorption coefficient or the reverberation time is input by operating a terminal, the control unit uses the input value when calculating the received sound signal.
7. The control unit is
   2. The acoustic characteristic analysis system according to claim 1, wherein, when at least one piece of information among the dimensions of the acoustic space, the characteristics of the acoustic space, the position of the sound source, the type of the sound source, and the position of the sound receiver in the acoustic space is changed by operating a terminal, the received signal is changed based on the changed information.
8. The acoustic characteristic analysis system according to claim 5 , wherein the control unit calculates the received sound signal based on the acoustic space information, the sound source information, the sound reception information, the average sound absorption coefficient, and a head related transfer function of the sound receiver.
9. The acoustic characteristic analysis system according to claim 5, wherein the control unit causes a display device to display a voice intelligibility based on the sound collected in the acoustic space by a sound collection device, the acoustic space information, the sound source information, and the sound reception information.
10. 2. The acoustic characteristic analysis system according to claim 1, wherein when it is assumed that the sound source is present in one of the two acoustic spaces adjacent to each other via a partition wall and a sound receiver is present in the other acoustic space, the control unit calculates the received sound signal based on information including an acoustic transmission loss of the partition wall.
11. 2. The acoustic characteristic analysis system according to claim 1, wherein the control unit calculates the received sound signal based on information including an acoustic transmission loss of a partition wall when it is assumed that a sound receiver is present in the acoustic space separated from an open space in which the sound source is provided by the partition wall.
12. the acoustic space is the virtual space,
    The acoustic characteristic analysis system according to claim 1 , wherein the characteristic is a reverberation time or an average sound absorption coefficient in the acoustic space.
13. The control unit is
    displaying an image corresponding to the sound source on a display device and displaying a predetermined character on the display device;
    13. The acoustic characteristic analysis system according to claim 12, wherein a position of a sound receiver who hears the sound of the sound source in the acoustic space is set as a position of the character.
14. The control unit is
    displaying an image corresponding to the sound source on a display device and displaying a predetermined character on the display device;
    13. The acoustic characteristic analyzing system according to claim 12, wherein the received sound signal is changed in response to a change in the position of the character or a change in the position of the sound source.
15. An acoustic characteristic analysis method that includes a process of outputting, as an audible signal, a received signal that is received when a user simulates the experience of hearing a sound from a specific sound source in an acoustic space, which may be a real space or a virtual space, based on the characteristics of the acoustic space.

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