Indoor ambient sound evaluation method and indoor ambient sound evaluation device

Abstract

To objectively evaluate desirably of an environmental sound in a room of an architectural structure with accuracy closed to human's feelings.SOLUTION: An evaluation method for environmental sounds in a room 32 of an architectural structure 30 comprises: steps (ST1, ST11) of detecting sounds in the room 32; step (ST2) of finding a sound source distribution in the room 2 based upon the detected sounds; and steps (ST3, ST7, ST13, ST17) of evaluating the environmental sounds in the room 32 based upon the sound source distribution. The environmental sounds in the room 32 are thus evaluated based upon the sound source distribution to perform properly evaluation with accuracy and objectivity close to human feelings.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an indoor environmental sound evaluation method for evaluating environmental sound in a building room and an indoor environmental sound evaluation device for evaluating environmental sound in a building room.

Background Art

[0002] When evaluating the influence of external noise on the interior, there is a known system for evaluating the living environment such as checking the noise level, rather than relying on noise evaluation by a specialist using the standard frequency characteristics of the sound insulation grade regarding the sound pressure level difference (Patent Document 1). This system calculates the indoor noise level value by subtracting the value attenuated by the distance between the noise source and the evaluation target room and the sound insulation performance value of the wall or window from the outdoor noise level value when designing a house using a computer, and displays the indoor noise level value together with the outdoor noise level value.

[0003] In the conventional environmental sound evaluation system, the evaluation of the sound environment in a living room or office used for living and work is carried out from the viewpoint that the quieter it is, the better, and the loudness (noise / sound pressure level) of the sound is used as an evaluation factor. On the other hand, people may feel comfort and preference in environmental sound. For example, in the environmental control system described in Patent Document 2, in order to improve work efficiency in an office, sound contents such as the sound of a small stream and music such as jazz and bossa nova are reproduced from speakers.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] <00When evaluating the comfort of the sound environment indoors, it is necessary to comprehensively evaluate various factors in addition to sound intensity, depending on the activity scenes of the people (occupants) in the room. However, there are few studies on methods for evaluating environmental sounds based on the comfort level, such as how pleasant or desirable the sound environment feels to people, and there are no established evaluation methods. Currently, there are only studies that focus on a few elements, such as the clarity of conversation or the degree of relaxation and healing, and there are almost no studies on the overall evaluation of the comfort of indoor environmental sounds that include other elements.

[0006] Physical parameters that have been used to understand the state of the indoor sound environment include loudness (sound pressure level), sound quality (frequency response), and temporal variation of sound (temporal variation of sound pressure level). By using these parameters, it is possible to understand the basic conditions of sound generation, such as how loud the sound is, whether it is high or low pitch, and the degree of variation in sound, such as whether it is constant, sporadic or irregular.

[0007] On the other hand, when people are in a coffee shop, for example, they may find it noisy but conducive to concentration and relaxation, meaning they may rate it as a more preferable sound environment than one with quieter sounds. In other words, it is thought that a person's preference for an indoor sound environment is derived from more information than can be explained by the basic sound information mentioned above. However, as stated above, there are currently no established parameters for evaluating the preference for an indoor sound environment, and there is no method to objectively evaluate whether an indoor sound environment is truly suitable and preferable for a person when they are engaged in activities indoors.

[0008] In particular, with the increased time spent at home due to the spread of teleworking during the COVID-19 pandemic, it is thought that people will have a greater need to bring the outside environment into their homes and feel closer to the outdoors in order to seek a greater sense of openness as they spend more time at home in enclosed spaces. Instead of the traditional idea of ​​blocking out outside noise and keeping the interior quiet, there is likely to be a growing need to bring outside noise into the interior or add other sounds to make the interior somewhat lively. On the other hand, the use of living spaces has diversified beyond traditional living (housework, family time, relaxation, etc.) to include work and hobbies, and furthermore, there are increasing cases where each family member is engaged in different activities within the same space, resulting in a variety of activity scenes that were not seen before within living spaces. In this situation, it is expected that the need to appropriately control and evaluate the indoor sound environment according to the activity scene will increase.

[0009] In view of the above background, the present invention aims to enable the appropriate evaluation of the desirableness of ambient sounds inside buildings with accuracy and objectivity that closely resembles human perception. [Means for solving the problem]

[0010] To solve the above problems, one aspect of the present invention is a method for evaluating ambient sound in the room of a building, comprising the steps of: detecting sound in the room (ST1); determining the sound source distribution in the room based on the detected sound (ST2); and evaluating the ambient sound in the room based on the sound source distribution (ST3, ST7).

[0011] According to this embodiment, by evaluating ambient sounds in a room based on the sound source distribution, it becomes possible to perform an appropriate evaluation with accuracy and objectivity that closely resembles human perception.

[0012] In the above embodiment, the steps for evaluating the ambient sound (ST3, ST7) may include a step of determining the dominance of the sound source based on the sound source distribution (ST3), and a step of calculating an evaluation value of the ambient sound based on the dominance of the sound source (ST7).

[0013] According to this embodiment, environmental sounds can be evaluated appropriately and reliably by calculating an evaluation value of the environmental sound based on the excellence of the sound source.

[0014] In the above embodiment, the excellence of the sound source is a numerical value that measures the degree of dispersion of the sound source within the room, and it is desirable that the higher the degree of dispersion, the better the evaluation value calculated.

[0015] According to this embodiment, the excellence of a sound source can be objectively calculated using a numerical value that scales the degree of dispersion of the sound source.

[0016] In the above embodiment, the step of detecting the sound (ST1) involves detecting multiple sound pressures propagating from multiple directions of arrival at a predetermined position in the room; the step of determining the excellence of the sound source (ST3) involves identifying the maximum value from among the multiple sound pressures, calculating the average value of multiple differences obtained by subtracting each of the multiple sound pressures from the maximum value as the excellence of the sound source; and the step of calculating the evaluation value (ST7) involves calculating the evaluation value such that a smaller excellence of the sound source is considered a better value.

[0017] According to this embodiment, an objective and unambiguous evaluation value can be calculated by using the average value of the difference between each sound pressure and the maximum value among multiple sound pressures.

[0018] In the above embodiment, the indoor ambient sound evaluation method further comprises the steps of determining at least one selected from the sound pressure, sound quality, and degree of change of sound pressure at the predetermined location in the room based on the detected sound (ST4, ST5, ST6), and in the step of calculating the evaluation value of the ambient sound (ST7), the evaluation value may be calculated using at least one selected from the sound pressure, sound quality, and degree of change of sound pressure in addition to the excellence or separation of the sound source.

[0019] According to this aspect, by using not only the sound source distribution but also at least one of the parameters of the sound evaluation that have been conventionally used, the environmental sound can be evaluated more appropriately.

[0020] In the above aspect, the step of evaluating the environmental sound may include a step (ST13) of calculating a degree of separation, which is a numerical value obtained by scaling the degree of dispersion of sound sources, based on the sound source distribution, and a step (ST17) of calculating an evaluation value of the environmental sound based on the degree of separation.

[0021] According to this aspect, by calculating the degree of separation obtained by scaling the degree of dispersion of a plurality of sound sources, the environmental sound can be evaluated appropriately and reliably.

[0022] In the step (ST13) of obtaining the degree of separation of the sound sources, for each region (i) where the sound source is located, the ratio ((Ki-Ji) / Ki) of the number (Ki-Ji) of regions adjacent to the region containing the sound source and not containing other sound sources adjacent to the region containing the sound source to the number (Ki) of regions adjacent to the region containing the sound source is calculated, and the average value of the ratios of each region where the sound source is located is calculated as the degree of separation of the sound source.

[0023] According to this aspect, by using the average value of the ratios calculated using the number of regions not containing other adjacent sound sources, an objective and unique evaluation value can be calculated.

[0024] In the above aspect, the indoor environmental sound evaluation method further includes a step (ST4, ST5, ST6) of obtaining at least one selected from the sound pressure, sound quality, and degree of change in the sound pressure at a predetermined position in the room based on the detected sound, and in the step (ST7) of calculating the evaluation value of the environmental sound, in addition to the degree of separation of the sound source, the evaluation value is calculated using the at least one selected from the sound pressure, sound quality, and degree of change in the sound pressure.

[0025] According to this aspect, by using not only the sound source distribution but also at least one of the parameters of the sound evaluation conventionally used, the environmental sound can be evaluated more appropriately.

[0026] Moreover, in order to solve the above problems, another aspect of the present invention is an indoor environmental sound evaluation device (10) for evaluating environmental sound in a room (32) of a building (30), including a sound detection device (11) for detecting the sound in the room, and an arithmetic device (14) configured to obtain the sound source distribution in the room based on the sound detected by the sound detection device and evaluate the environmental sound in the room based on the sound source distribution.

[0027] According to this aspect, by evaluating the environmental sound in the room based on the sound source distribution, an appropriate evaluation with accuracy and objectivity close to human perception becomes possible.

[0028] In the above aspect, it is preferable that the sound detection device includes an array microphone (11) including a plurality of microphones (12) for detecting sound pressures from a plurality of arrival directions.

[0029] According to this aspect, a plurality of sound pressures that are the basis of the sound source distribution in the room can be directly detected by the array microphone.

Effect of the Invention

[0030] According to the above aspects, the preference of the environmental sound in the room of the building can be appropriately evaluated with accuracy and objectivity close to human perception.

Brief Description of the Drawings

[0031] [Figure 1] Schematic Configuration Diagram of Indoor Environmental Sound Evaluation Device According to First Embodiment [Figure 2] Explanation Diagram of Relationship between Detection Results of Array Microphone and Dominance of Sound Sources in Room [Figure 3] Flowchart Showing Procedure of Indoor Environmental Sound Evaluation Process According to First Embodiment [Figure 4] Floor Plan of Room Used in Experiment [Figure 5] Schematic diagram of the indoor environmental sound evaluation device according to the second embodiment. [Figure 6] Diagram illustrating the relationship between the placement of sound sources in a room and their degree of separation. [Figure 7] Diagram illustrating the relationship between the placement of sound sources in a room and their degree of separation. [Figure 8] Flowchart showing the procedure for evaluating indoor ambient noise according to the second embodiment. [Figure 9] A diagram showing the results of the separation and concentration levels obtained from the experiment. [Modes for carrying out the invention]

[0032] Hereinafter, several embodiments of the present invention will be described in detail with reference to the drawings.

[0033] ≪First Embodiment≫ Figure 1 is a schematic diagram of the indoor ambient sound evaluation device 10 according to an embodiment. As shown in Figure 1, the indoor ambient sound evaluation device 10 is a device for evaluating ambient sound in the interior 32 (see Figure 4) of a building 30.

[0034] The indoor ambient sound evaluation device 10 includes an array microphone 11 placed in the room 32 to detect sounds in the room 32. The array microphone 11 comprises a plurality of microphones 12 arranged in a directional manner. Each microphone 12 has a directional principal axis to detect sound waves propagating from a predetermined direction. The plurality of microphones 12 are arranged so that their directional principal axes face in different directions from each other and are fixed to the base member of the array microphone 11.

[0035] The array microphone 11 has a plurality of microphones 12 arranged so that their directional principal axes are horizontally oriented at equal angular intervals in the horizontal direction, and at least one microphone 12 arranged so that its directional principal axis is oriented vertically. The array microphone 11 of this embodiment has a total of nine microphones 12, including eight microphones 12 whose directional principal axes are horizontally oriented at 45-degree intervals in the horizontal direction, and one microphone 12 whose directional principal axis is oriented vertically downward. Each microphone 12 detects sound waves incident from the direction of its directional principal axis.

[0036] The indoor ambient sound evaluation device 10 also includes a computer 13 for evaluating ambient sound in the room 32 based on the sound detected by the array microphone 11. The computer 13 includes an arithmetic processing unit (CPU, MPU, etc., processor) and a memory device (ROM, RAM, etc., memory), and includes an arithmetic unit 14 configured to perform various processes necessary for indoor ambient sound evaluation. Being configured to perform various processes means that the arithmetic processing unit (processor) is programmed to read necessary data and application software from the memory device and to perform the predetermined arithmetic processes according to the software. The arithmetic unit 14 may be configured as a single piece of hardware, or as a unit consisting of multiple pieces of hardware.

[0037] The calculation unit 14 includes, as functional units, a sound source distribution acquisition unit 15, an excellence calculation unit 16, a sound pressure calculation unit 17, a sound quality calculation unit 18, a sound pressure change calculation unit 19, and an evaluation value calculation unit 20.

[0038] The sound source distribution acquisition unit 15 acquires the sound source distribution based on the sounds detected by the array microphone 11. Specifically, the sound source distribution acquisition unit 15 associates the sounds detected by each microphone 12 of the array microphone 11 with the region in which the microphone 12 is directed (one of the regions when the room 32 is divided into multiple regions), as sounds having a sound source in that region. Alternatively, the sound source distribution acquisition unit 15 may perform predetermined calculation and filtering processes on the sounds detected by each microphone 12 to calculate the sound sources in the corresponding regions, and then associate each sound source with the corresponding region to acquire the sound source distribution.

[0039] The excellence calculation unit 16 calculates the excellence of a sound source based on multiple sound pressures (sound pressure levels) associated with each region, i.e., the sound source distribution. For each sound, the excellence calculation unit 16 calculates the average value of the sound pressure detected over a predetermined time as a sound having a sound source in the corresponding region, and uses these sounds to calculate the excellence of the sound source.

[0040] Figure 2 is an explanatory diagram illustrating the relationship between the detection results of the array microphone 11 and the dominance of the sound source in the room 32. As shown in Figure 2, the array microphone 11 detects sound in the room 32 using nine directional microphones 12. Hereinafter, the areas pointed to by the eight microphones 12 whose directional principal axes are oriented horizontally will be referred to as regions 1 to 8, and the area pointed to by the microphone 12 whose directional principal axis is oriented vertically downward will be referred to as region 9. That is, region 9 is the area that includes the position where the array microphone 11 is placed, and regions 1 to 8 are the eight areas surrounding region 9. In the figure, the numbers indicating regions are enclosed in circles. The area located in the upper center of the page is set as region 1, and regions 2 to 8 are arranged in order clockwise from region 1.

[0041] For simplicity, this explanation assumes that each microphone 12 detects either loud or soft sounds. In the example in Figure 2(A), loud sounds are detected in the second region, and soft sounds are detected in the other regions. In the example in Figure 2(B), loud sounds are detected in the second and fifth regions, and soft sounds are detected in the other regions. In the example in Figure 2(C), loud sounds are detected in the first, second, fourth, fifth, and seventh regions, and soft sounds are detected in the other regions (third, seventh, and ninth regions).

[0042] The sound detected by each microphone 12 of the array microphone 11 is treated as a sound having a sound source in the corresponding region among the 1st to 9th regions that divide the room 32 (i.e., it is evaluated as a sound having a sound source in the corresponding region). For example, in the example in Figure 2(A), a large sound source is evaluated in the 2nd region of the room 32. In the example in Figure 2(B), large sound sources are evaluated in the 2nd and 5th regions of the room 32. In the example in Figure 2(C), large sound sources are evaluated in the 1st, 2nd, 4th, 5th and 7th regions of the room 32.

[0043] The excellence calculation unit 16 calculates the excellence (S) of the sound source by performing the following calculation (1). S = Σ(Lmax - Ln) / n ···(1) However, S is the excellence of the sound source, Lmax is the maximum value of the detected sound pressure, Ln is the sound pressure of the nth region, and n is the number of regions.

[0044] In the example shown in Figure 2(A), the number of regions where a small sound is detected and the value of (Lmax-Ln) is calculated as a positive value is "8," which is a large number. Therefore, the sound source excellence (S) is calculated to be a relatively large value, indicating high sound source excellence. In other words, sound source excellence is a parameter that measures the degree of sound source dispersion. A larger value indicates lower sound source dispersion (higher sound source excellence), while a smaller value indicates higher sound source dispersion (lower sound source excellence).

[0045] In the example shown in Figure 2(B), the number of regions where a small sound was detected is slightly low at "7," so the excellence of the sound source is calculated to be a slightly lower value. Therefore, this value is evaluated as indicating that the dispersion of the sound source has slightly improved, and the excellence of the sound source has slightly decreased.

[0046] In the example shown in Figure 2(C), the number of regions where a small sound was detected is even smaller, at "4," so the excellence of the sound source is calculated to be an even smaller value. Therefore, this value is evaluated as indicating good sound source dispersion and low sound source excellence.

[0047] Returning to Figure 1, the sound pressure calculation unit 17 calculates the sound pressure in the room 32 based on the detected sound. Sound pressure is a parameter that represents the magnitude of the detected sound. The sound pressure calculation unit 17 calculates the sound pressure in the room 32 (more precisely, the sound pressure at the array microphone placement locations in the room 32) by adding up the sound pressures for each region detected by the microphone 12, for example, using equation (2) below. L=10*log(Σ(10 (Ln / 10) )) ···(2) However, L is the sound pressure after summation, and Ln is the sound pressure of the nth region. The sound pressure calculation unit 17 calculates the average value of the sound pressure detected over a predetermined time for each sound, treating it as a sound with a sound source in the corresponding region, and uses these sounds to calculate the sound pressure.

[0048] The sound quality calculation unit 18 calculates the sound quality of the room 32 based on the detected sound. Sound quality is a parameter that represents the frequency characteristics (high and low frequencies) of the detected sound. The sound quality calculation unit 18 calculates the sound quality of the room 32 (more precisely, the sound quality at the array microphone placement position in the room 32) using, for example, a sound obtained by superimposing sounds from different regions detected by the microphone 12. For example, a numerical value is calculated as the sound quality that is evaluated as good when it contains many sounds in the frequency range that people find pleasant. Alternatively, a numerical value that measures the degree of dispersion of the frequencies of the detected sound may be calculated as the sound quality. For example, if the detected sound contains many specific frequencies, it is evaluated as having poor sound quality, and if the detected sound evenly covers the entire frequency range from low to high frequencies, a numerical value is calculated as the sound quality that is evaluated as having good sound quality. The sound quality calculation unit 18 may calculate the sound quality as the average value of the sound quality detected over a predetermined period of time.

[0049] The sound pressure change calculation unit 19 calculates the sound pressure change in the room 32 based on the detected sound changes. Specifically, the sound pressure change calculation unit 19 calculates the amount of change in sound pressure per unit time calculated by the sound pressure calculation unit 17 over a predetermined period of time, and calculates the sound pressure change from these change amounts. For example, the sound pressure change calculation unit 19 calculates the sound pressure change as the integral value of the amount of change in sound pressure per unit time.

[0050] The evaluation value calculation unit 20 calculates an evaluation value for the sound in the room 32 based on the calculated excellence of the sound source, the sound pressure in the room 32, the sound quality of the room 32, and the change in sound pressure in the room 32. For example, the evaluation value calculation unit 20 calculates the evaluation value by multiplying or dividing these values. Typically, the evaluation value may be a parameter in which a smaller value indicates a better sound in the room 32. In this case, both sound pressure and excellence of the sound source are used as multiplicative values. That is, the evaluation value is calculated to be smaller the smaller the sound pressure and excellence of the sound source, and the smaller the evaluation value, the better the ambient sound in the room 32 is considered to be. Alternatively, an optimal value may be set according to the person or space being studied, and the closer the evaluation value is to the optimal value, the better it is considered to be. The evaluation value calculation unit 20 may weight the values ​​used to calculate the evaluation value, and may also calculate the evaluation value by incorporating a predetermined conditional expression.

[0051] The computer 13 further includes a display device 21. The display device 21 displays evaluation values ​​for the sound in the room 32 calculated by the arithmetic unit 14 in one of the following formats: numerical values, figures, graphs, or tables. The display device 21 may further display the excellence of the sound source, the sound pressure in the room 32, the sound quality of the room 32, and the change in sound pressure in the room 32 in one of the following formats: numerical values, figures, graphs, or tables. By looking at the display device 21, the user can visually confirm the evaluation values ​​for the sound in the room 32, which are evaluated based on the sound detected by the array microphone 11.

[0052] Thus, the indoor ambient sound evaluation device 10 comprises an array microphone 11 as a sound detection device and a computing device 14. The computing device 14 is configured to determine the sound source distribution in the room 32 based on the sound detected by the array microphone 11, and to evaluate the ambient sound in the room 32 based on the sound source distribution. By evaluating the ambient sound in the room 32 based on the sound source distribution, the indoor ambient sound evaluation device 10 can appropriately evaluate the ambient sound with an accuracy and objectivity close to that of human perception.

[0053] Furthermore, the array microphone 11 is equipped with multiple microphones 12 that detect sound pressure from multiple directions of arrival. This makes it possible to directly detect multiple sound pressures that form the basis of the sound source distribution in the room 32 using the array microphone 11.

[0054] Figure 3 is a flowchart showing the procedure for evaluating indoor ambient sound according to the first embodiment. As shown in Figure 3, when the indoor ambient sound evaluation device 10 is powered on, it performs the indoor ambient sound evaluation process shown in Figure 3. First, the indoor ambient sound evaluation device 10 detects sounds in the room 32 using the array microphone 11 (step ST1). Based on the detected sounds, the indoor ambient sound evaluation device 10 determines the sound source distribution in the room 32 (step ST2).

[0055] Subsequently, the indoor ambient sound evaluation device 10 determines the dominance of the sound source based on the sound source distribution (step ST3). Specifically, the indoor ambient sound evaluation device 10 identifies the maximum value from among the multiple sound pressures detected by the microphone 12, and calculates the dominance of the sound source as the average value of the multiple differences obtained by subtracting each of the multiple sound pressures from the maximum value.

[0056] Furthermore, the indoor ambient sound evaluation device 10 determines the sound pressure at a predetermined location in the room 32 based on the detected sound (step ST4). The indoor ambient sound evaluation device 10 determines the sound quality at a predetermined location in the room 32 based on the detected sound (step ST5). The indoor ambient sound evaluation device 10 determines the degree of change in sound pressure at a predetermined location in the room 32 based on the detected sound (step ST6).

[0057] Next, the indoor ambient sound evaluation device 10 evaluates the ambient sound in the room 32 based on the excellence of the sound source, sound pressure, sound quality, and degree of change in sound pressure obtained in steps ST3, ST4, ST5, and ST6 (step ST7). In step ST7, it is sufficient that the evaluation value is calculated using at least one of the sound source excellence, sound pressure, sound quality, and degree of change in sound pressure. With this, the indoor ambient sound evaluation device 10 terminates the indoor ambient sound evaluation process. The indoor ambient sound evaluation device 10 may continue each of the above processes until the power is turned off.

[0058] Thus, the method for evaluating ambient sound in this embodiment comprises steps ST2, which determines the sound source distribution in the room 32 based on the detected sound, and steps ST3 and ST7, which evaluate the ambient sound in the room 32 based on the sound source distribution. By evaluating the ambient sound in the room 32 based on the sound source distribution, it becomes possible to perform an appropriate evaluation with accuracy and objectivity close to human perception.

[0059] Furthermore, the method for evaluating ambient sound includes step ST3, which determines the dominance of sound sources based on the sound source distribution, and step ST7, which calculates an evaluation value for ambient sound based on the dominance of sound sources. By calculating an evaluation value for ambient sound based on the dominance of sound sources, it becomes possible to evaluate ambient sound appropriately and reliably.

[0060] As described above, the excellence of a sound source is a numerical value that measures the degree of dispersion of sound sources in Room 32. The higher the degree of dispersion, the better the evaluation value calculated, so the excellence of a sound source can be objectively calculated using this value.

[0061] In step ST3, which determines excellence, the excellence of the sound source is calculated by taking the average of multiple differences obtained by subtracting each of the multiple sound pressures from the maximum value of the multiple sound pressures. In step ST7, which calculates the evaluation value, the lower the excellence of the sound source, the better the evaluation value calculated. In this way, by using the average of the differences of each sound pressure relative to the maximum value of the multiple sound pressures, an objective and unambiguous evaluation value is calculated.

[0062] Furthermore, in step ST7, which calculates the evaluation value of ambient sound, the evaluation method for ambient sound uses at least one selected from sound pressure, sound quality, and the degree of change in sound pressure, in addition to the excellence of the sound source. In this way, by using at least one of the conventional sound evaluation parameters in addition to the sound source distribution, it becomes possible to evaluate ambient sound more appropriately.

[0063] Next, we will explain the indoor environmental sound evaluation experiment conducted by the inventors. The A-weighted sound pressure level (noise level) is widely used as an index to evaluate the sound environment in indoor spaces such as living spaces 32. This index is mainly evaluated from the perspective that a quieter indoor space 32 is better. On the other hand, in this experiment, we focused on the dominance of sound sources determined from the sound source distribution and investigated the relationship between dominance and auditory impression.

[0064] Figure 4 is a floor plan of the room used in the experiment. As shown in Figure 4, the room is a room in a reinforced concrete building 30 and measures approximately 5m x 8m. The ceiling height of the room is 2,670mm. The room 32 contains four desks 33, one table 34, and a shelf 35. The table 34 is positioned near the center on the right side of the room, and several chairs 36 are arranged around the table 34. Partitions 37 are placed between each of the desks 33 and the table 34. In the experiment, speakers SP2 and SP3 were placed on the two desks 33 positioned above the paper, and speaker SP4 was placed on the shelf 35 positioned below the paper. To evaluate the ambient sound of the room 32 as perceived by a person sitting around the table 34, an array microphone 11 was placed on the table 34. In the figure, the array microphone 11 is indicated as "AR". The array microphone 11 is positioned so that the top of the paper is the first region, as shown on the right side of the figure. The subject sat in a chair 36 positioned in the lower left of the paper relative to the table 34.

[0065] In the experiment, to investigate how well participants could tolerate ambient noise while performing tasks such as reading, two sound sources—two types of conversational sounds and a combination of conversational sounds and background music—were played simultaneously. The volume of the other sound source was adjusted so that the conversational sound was no longer bothersome. Two participants took turns performing the experiment. Each participant was instructed to perform a task, such as reading a newspaper, while the test sound was being played.

[0066] Table 1 shows the combinations of test sounds and their playback positions for each experimental pattern. There were three types of test sounds: male announcement conversation 1, female announcement conversation 2, and jazz music BGM 1. For the sound pressure level setting during playback, the speaker SP level was set so that the A-weighted sound pressure level at a point 30 cm away from the speaker SP was 80 dB when conversation 1 was played. The combinations of test sounds were three patterns: conversation 1-low (A-weighted sound pressure level: 70 dB) was played at a constant level from SP3 as the target for masking, and conversation 2 was played from SP2, BGM 1 from SP4, and BGM 1 from SP2 to mask it.

[0067] [Table 1]

[0068] The adjustment procedure involved first playing Conversation 1 (low volume) from SP3 and another audio source (for example, Conversation 2 from SP2) simultaneously, while the subject listened while performing an activity such as reading a newspaper. The subject was asked to focus on whether the audio source of Conversation 1 was bothersome and to indicate whether the other audio source was loud or quiet. Next, the playback levels were adjusted based on this feedback and the audio was played again. This process was repeated until the subject felt that Conversation 1 was no longer bothersome.

[0069] Table 2 shows the results of adjusting the playback level for each combination of test sounds, along with the subjects' feedback during the process. The volume adjustment levels in the table are expressed as relative values ​​with no adjustment set to 0 dB. The hatched rows indicate the point at which the subject felt the sound source of Conversation 1 was no longer bothersome, and the playback level adjustment was completed.

[0070] [Table 2]

[0071] To examine subjective evaluation and sound source excellence, we attempted to define and calculate sound source excellence using the following equation (3). In this experiment, we calculated the average difference between the maximum sound source intensity, i.e., sound pressure, and the sound pressure of each region obtained by the array microphone 11 in each of the nine directions. The larger the average difference from the maximum value (sound source excellence), the more it indicates that the sound pressure in other regions is relatively small compared to the region showing the maximum value. In other words, if the sound source is concentrated in a certain region and the sound pressure in that region is high, the value of sound source excellence will be large.

number

[0072] Table 3 shows the sound pressure of sound sources in each direction and the excellence calculated from the results in the initial state before adjustment and the state after adjustment using the method described above. Note that these results are for the frequency band of 1 to 5 kHz. Comparing the initial state before adjustment with the state after adjustment, a tendency for excellence to decrease was observed in all patterns. This indicates that, when performing tasks such as reading a newspaper, the excellence of the sound source can be an indicator for evaluating whether the sounds in the room are bothersome during the task.

[0073] [Table 3]

[0074] The experimental results above show that by calculating the dominance of sound sources based on the sound source distribution and evaluating the ambient sound in room 32 based on the dominance of sound sources, it becomes possible to perform an appropriate evaluation with accuracy and objectivity that closely resembles human perception.

[0075] ≪Second Embodiment≫ Next, a second embodiment of the present invention will be described with reference to Figures 5 to 9. Elements identical or similar to those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0076] In the second embodiment, a room ambient sound evaluation device 10 that uses the degree of sound source separation as an evaluation value for ambient sound will be described. The degree of separation measures the degree of dispersion of sound sources when sound sources are present in the room 32. When there is one sound source, the degree of separation is calculated as the highest value. When there are multiple sound sources and each of the multiple sound sources is close to each other, the sound from each sound source is easily observed over a certain unified direction. When each of the multiple sound sources is far from each other, the sound from each sound source is easily observed over multiple directions. In a room 32 that is divided into several regions, the degree of separation is preferably calculated based on the number of surrounding regions adjacent to the region where the sound source is located, and the number of regions that do not contain other sound sources.

[0077] As shown in Figure 5, the array microphone 11 provided in the indoor ambient sound evaluation device 10 is the same as in the first embodiment. Hereinafter, the areas pointed to by the eight microphones 12 whose directional principal axes are oriented horizontally will be referred to as the 1st to 8th regions, and the area pointed to by the microphone 12 whose directional principal axis is oriented vertically downward will be referred to as the 9th region. That is, the 9th region is the region that includes the position where the array microphone 11 is arranged, and the 1st to 8th regions are the eight regions surrounding the 9th region. In the figure, the numbers indicating the regions are enclosed in circles. The region located in the upper center of the page is set as the 1st region, and the 2nd to 8th regions are arranged in order clockwise from the 1st region.

[0078] The calculation unit 14 of the indoor ambient sound evaluation device 10 has, as functional units, a sound source distribution acquisition unit 15, a separation degree summation unit 22, a sound pressure calculation unit 17, a sound quality calculation unit 18, a sound pressure change calculation unit 19, and an evaluation value calculation unit 20.

[0079] The sound source distribution acquisition unit 15 acquires the distribution of sound sources based on the sounds detected by the array microphone 11. Specifically, the sound source distribution acquisition unit 15 associates the sounds detected by each microphone 12 of the array microphone 11 with the area that the microphone 12 points towards (one of the areas when the room 32 is divided into multiple areas).

[0080] The separation degree summation unit 22 first calculates the presence or absence of a sound source based on multiple sound pressures (sound pressure levels) associated with each region, i.e., the sound source distribution. Specifically, for each region, the separation degree summation unit 22 associates the average value of the sound pressure detected over a predetermined time with the corresponding region. The separation degree summation unit 22 calculates the average of the average sound pressures associated with the corresponding region and calculates this average value as the sound pressure of the room 32. The separation degree summation unit 22 compares the average value of the sound pressures associated with each region with the sound pressure of the room 32. If the average value of the associated sound pressures is greater than or equal to the sound pressure of the room 32, the separation degree summation unit 22 calculates that there is a sound source in that region. If the average value of the associated sound pressures is less than the sound pressure of the room 32, the separation degree summation unit 22 calculates that there is no sound source in that region.

[0081] The separation degree calculation unit 22 calculates the degree of separation of sound sources for the region containing the sound sources using the following formula (4).

number

[0082] The degree of separation is calculated as a positive value of "1" or less. As shown in Figure 6(A), in the case of two sound sources placed in the 8th and 4th regions, the surrounding regions adjacent to the region where one sound source is placed do not include the region where the other sound source is placed. Let's explain how to calculate the degree of separation in this case. First, the number of regions adjacent to the 8th region is "3". Also, the number of regions adjacent to the 8th region that contain the other sound source is "0". Therefore, the number of regions adjacent to the 8th region that do not contain the other sound source is "3-0=3". Thus, the ratio of the number of surrounding regions adjacent to the 8th region to the number of surrounding regions adjacent to the 8th region that do not contain the other sound source is "3 / 3=1".

[0083] Next, the number of regions adjacent to the fourth region is "3". Also, the number of regions adjacent to the fourth region that contain other sound sources is "0". Therefore, the number of regions adjacent to the fourth region that do not contain other sound sources is "3-0=3". Thus, the ratio of the number of surrounding regions adjacent to the fourth region to the number of surrounding regions adjacent to the fourth region that do not contain other sound sources is "3 / 3=1".

[0084] In regions that do not contain a sound source, the ratio of the number of adjacent regions to that region to the number of adjacent regions that do not contain other sound sources is treated as "0". Therefore, the sum of these ratios is "1 + 1 = 2". The degree of separation is calculated by dividing the sum of these ratios by the number of sound sources. That is, the degree of separation is "2 / 2 = 1". Note that even when there is only one sound source, the degree of separation is "1".

[0085] As shown in Figure 6(B), in a case where two sound sources are placed in the 8th region and the 1st region, the surrounding regions adjacent to the region where one sound source is placed include the region where the other sound source is placed. Let's explain how to calculate the degree of separation in this case. First, the number of regions adjacent to the 8th region is "3". Also, the number of regions adjacent to the 8th region that contain the other sound source is "1". Therefore, the number of regions adjacent to the 8th region that do not contain the other sound source is "3-1=2". Thus, the ratio of the number of surrounding regions adjacent to the 8th region to the number of surrounding regions adjacent to the 8th region that do not contain the other sound source is "2 / 3".

[0086] Next, the number of regions adjacent to the first region is "5". Also, the number of regions adjacent to the first region that contain other sound sources is "1". Therefore, the number of regions adjacent to the first region that do not contain other sound sources is "5-1=4". Thus, the ratio of the number of surrounding regions adjacent to the first region to the number of surrounding regions adjacent to the first region that do not contain other sound sources is "4 / 5".

[0087] In regions that do not contain a sound source, the ratio of the number of adjacent regions to that region to the number of adjacent regions that do not contain other sound sources is treated as "0". Therefore, the sum of these ratios is "(2 / 3) + (4 / 5) = 22 / 15". The degree of separation is calculated by dividing the sum of these ratios by the number of sound sources. That is, the degree of separation is rounded to the third decimal place, resulting in "(22 / 15) / 2 = 0.73".

[0088] The above two examples demonstrate that the degree of separation can be used to measure the degree of dispersion of multiple sound sources. A separation degree closer to "1" indicates a high degree of dispersion of multiple sound sources, meaning that the sounds from each source are more easily observable in multiple directions. Conversely, a separation degree closer to "0" indicates a low degree of dispersion of multiple sound sources, meaning that the sounds from each source are more easily observable in a concentrated, single direction.

[0089] As shown in Figures 7(A) to (C), the degree of separation changes depending on the arrangement of the five sound sources. In Figures 7(A) to (C), the diagram on the left of the page shows the arrangement of sound sources in predetermined positions within each region. In Figures 7(A) to (C), the diagram on the right of the page shows the ratio of the number of surrounding regions adjacent to the region containing a sound source to the number of surrounding regions adjacent to that region that do not contain other sound sources. In Figure 7(A), the degree of separation is "0.79," which is close to "1," indicating that the sound sources are widely dispersed and that the sound from each source is easily observable in multiple directions. In Figure 7(B), the degree of separation is "0.68," which is slightly lower than in Figure 7(A), indicating that the sound from each source is easily observable in multiple directions. In Figure 7(C), the degree of separation is "0.49," which is even lower than "1." Therefore, the sound from each sound source is considered to be easily observable across a certain unified, unidirectional direction.

[0090] The evaluation value calculation unit 20 calculates an evaluation value for the sound in the room 32 based on the calculated separation degree, the sound pressure in the room 32, the sound quality of the room 32, and the change in sound pressure in the room 32. For example, an optimal value may be set according to the target person or space, and an evaluation value closer to the optimal value is considered to be better. The evaluation value calculation unit 20 may weight the values ​​used to calculate the evaluation value, or it may calculate the evaluation value by incorporating a predetermined conditional expression.

[0091] Figure 8 is a flowchart showing the procedure for the indoor ambient sound evaluation process according to the second embodiment. As shown in Figure 8, the processes of steps ST11, ST12, and ST14 to ST16 are the same as the processes of steps ST1, ST2, and ST4 to ST6 in the first embodiment, so their explanation is omitted.

[0092] In step ST13, the indoor ambient sound evaluation device 10 determines the degree of sound source separation based on the sound source distribution. Specifically, the indoor ambient sound evaluation device 10 first calculates the average value of multiple sound pressures detected by the microphone 12, and calculates that there is a sound source in areas with a sound pressure above this average value. However, the reference level for the presence or absence of a sound source does not necessarily have to be the average value. For example, depending on the sound source conditions of the target room, the presence or absence of a sound source may be determined using a value larger or smaller than the average value as the reference level. Next, the indoor ambient sound evaluation device 10 calculates the ratio of the number of areas adjacent to the area where the sound source is located to the number of areas that do not contain other sound sources, and calculates the degree of separation by dividing the sum of the ratios calculated for each area containing a sound source by the number of sound sources.

[0093] Next, in step ST17, the indoor ambient sound evaluation device 10 evaluates the ambient sound in the room 32 based on the degree of separation, sound pressure, sound quality, and degree of change in sound pressure obtained in steps ST13, ST14, ST15, and ST16. In step ST17, it is sufficient that the evaluation value is calculated using at least one selected from the degree of separation of sound sources, sound pressure, sound quality, and degree of change in sound pressure. With this, the indoor ambient sound evaluation device 10 terminates the indoor ambient sound evaluation process. The indoor ambient sound evaluation device 10 may continue each of the above processes until the power is turned off.

[0094] Thus, the method for evaluating ambient sound includes step ST13, which determines the degree of separation of sound sources based on the sound source distribution, and step ST17, which calculates an evaluation value for ambient sound based on the degree of separation of sound sources. By calculating an evaluation value for ambient sound based on the degree of separation of sound sources, it becomes possible to evaluate ambient sound appropriately and reliably.

[0095] Furthermore, in step ST13, which determines the degree of sound source separation, as shown in equation (4) above, for each region (i) containing a sound source, the ratio "(Ki-Ji) / Ki" is calculated, which is the ratio of the number of regions adjacent to the region containing the sound source that do not contain other sound sources (Ki-Ji) to the number of regions adjacent to the region containing the sound source (Ki). The average value of this ratio for each region containing a sound source is then calculated as the degree of sound source separation (α). In this way, by using the average value of the ratio calculated using the number of adjacent regions that do not contain other sound sources, an objective and unambiguous evaluation value can be calculated.

[0096] Furthermore, in step ST17, which calculates the evaluation value of ambient sound, the evaluation method for ambient sound uses at least one selected from sound pressure, sound quality, and the degree of change in sound pressure, in addition to the degree of separation of sound sources. In this way, by using at least one of the conventional sound evaluation parameters in addition to the sound source distribution, it becomes possible to evaluate ambient sound more appropriately.

[0097] Next, we will explain the indoor environmental sound evaluation experiment conducted by the inventor. In this experiment, we focused on the degree of separation, which is a numerical value that measures the degree of dispersion of multiple sound sources, and examined the relationship between the degree of separation and the auditory impression.

[0098] The experimental method involves the experimenter first placing a sound source, primarily consisting of conversation, and an array microphone 11, which is equipped with an indoor ambient sound evaluation device 10, in the room 32. The array microphone 11 should be placed near the subject. The experimenter simultaneously plays multiple sound sources. As a result, the sounds detected by the array microphone 11 are acquired as a sound source distribution by the sound source distribution acquisition unit 15. The degree of separation is calculated by the degree of separation summation calculation unit 22 based on the acquired sound source distribution. The degree of separation is defined and calculated by the above equation (4).

[0099] Next, the experimenter had the subjects read while a sound source was playing. In this situation, the subjects rated their level of concentration on a 7-point scale from 1 to 7, indicating how well they could concentrate on reading. In the rating, "1" was the lowest level of concentration, and "7" was the highest level of concentration. After the subjects' evaluations, the experimenter changed the arrangement of several sound sources and had the same subjects evaluate under different levels of separation. The experimenter conducted six experiments with the same subjects in a room with the same level of separation.

[0100] As shown in Figure 9, in this experiment, the experimenter changed the arrangement of multiple sound sources four times, i.e., used four different degrees of separation, and had subjects evaluate their level of concentration. The dots in Table 3 represent the average value of the six trials. The upper end of the vertical line extending upwards from the dots indicates the value obtained by adding the standard deviation of the concentration levels obtained from the six experiments to the average value (dot). The lower end of the vertical line extending downwards from the dots indicates the value obtained by subtracting the standard deviation of the concentration levels obtained from the six experiments from the average value (dot).

[0101] When comparing the degree of concentration at each degree of separation, a tendency was observed for the degree of concentration to change depending on the degree of separation. This suggests that, in activities such as reading, the degree of separation of multiple sound sources placed in room 32 can serve as an indicator for evaluating whether or not they are distracting during reading.

[0102] Based on the experimental results described above, it is possible to evaluate ambient sounds in more detail by combining the degree of separation, which measures the degree of dispersion of multiple sound sources, with sound pressure, sound quality, and the degree of change in sound pressure.

[0103] This concludes the description of specific embodiments. However, the present invention is not limited to the above embodiments or modifications and can be broadly modified and implemented. For example, in the above embodiment, an array microphone 11 is used as the sound detection device, but multiple microphones 12 may be arranged in corresponding areas. Also, in the flowchart of Figure 3, the calculation of sound pressure (ST4, ST14), sound quality (ST5, ST15), and the calculation of the degree of change in sound pressure (ST6, ST16) are performed after the calculation of sound source excellence (ST3) or separation degree (ST13). However, these processes may be performed after sound detection (ST1, ST11) and before the calculation of sound source excellence (ST3) or separation degree (ST13).

[0104] In the above embodiment, the room 32 is divided into nine 3x3 regions in Figures 2, 6, and 7. These regions are set up for convenience to explain the superiority and separation of the sound source, and the number of regions is not limited to these.

[0105] Furthermore, the above embodiments can be combined as appropriate. For example, the calculation unit 14 may include both an excellence calculation unit 16 and a separation degree calculation unit 22. In this case, the evaluation value calculation unit 20 calculates an evaluation value for the sound in the room 32 based at least on the excellence and separation degree of the sound source. The evaluation value calculation unit 20 may further calculate an evaluation value for the sound in the room 32 using the sound pressure of the room 32, the sound quality of the room 32, and the change in sound pressure of the room 32. By calculating the evaluation value based on both the excellence and separation degree of the sound source in this way, ambient sound can be evaluated more appropriately and reliably than when the evaluation value is calculated using only one of the excellence or separation degree of the sound source.

[0106] In addition, the specific processing and sequence of the evaluation method, the specific configuration, arrangement, quantity, and angles of the components and functional parts of the indoor environmental sound evaluation device 10 can be modified as appropriate, as long as they do not depart from the spirit of the present invention. On the other hand, not all of the components shown in the above embodiment are necessarily essential, and can be selected as appropriate. [Explanation of Symbols]

[0107] 1: Building 2:Indoor 10: Indoor environmental sound evaluation device 11: Array Microphone 12: Mike 13: Computer 14: Arithmetic device 15: Sound source distribution acquisition section 16: Excellence Calculation Department 17: Sound pressure calculation unit 18:Sound quality calculation section 19: Sound pressure change calculation unit 20: Evaluation value calculation unit 21:Display device 22: Separation degree calculation unit

Claims

1. A method for evaluating ambient noise inside a building, The steps include detecting the sound inside the room, A step of determining the sound source distribution within the room based on the detected sound, The process includes a step of evaluating the ambient sound in the room based on the sound source distribution, The step of evaluating the aforementioned ambient sound is: Based on the aforementioned sound source distribution, the steps include determining the superiority of the sound source, The step of calculating an evaluation value of the ambient sound based on the excellence of the sound source includes: In the step of detecting the sound, multiple sound pressures propagating from multiple directions of arrival are detected at a predetermined location in the room. In the step of determining the excellence of the sound source, the maximum value is identified from among the multiple sound pressures, and the average value of the multiple differences obtained by subtracting each of the multiple sound pressures from the maximum value is calculated as the excellence of the sound source. A method for evaluating indoor environmental sound, wherein in the step of calculating the evaluation value, the smaller the excellence of the sound source, the better the value is calculated.

2. The method for evaluating indoor environmental sound according to claim 1, wherein the excellence of the sound source is a numerical value that measures the degree of dispersion of the sound source in the room, and the higher the degree of dispersion, the better the evaluation value calculated.

3. The further step is to determine, based on the detected sound, at least one selected from the sound pressure, sound quality, and degree of change of sound pressure at the predetermined location in the room, The indoor ambient sound evaluation method according to claim 1 or 2, wherein in the step of calculating the evaluation value of the ambient sound, the evaluation value is calculated using at least one selected from the sound pressure, sound quality, and degree of change of the sound pressure, in addition to the excellence of the sound source.

4. The step of evaluating the aforementioned ambient sound is: The steps include: calculating a degree of separation, which is a numerical value that scales the degree of dispersion of the sound sources, based on the aforementioned sound source distribution; A method for evaluating indoor ambient noise according to claim 1 or 2, comprising the step of calculating the evaluation value of the ambient noise based on the degree of separation.

5. A method for evaluating ambient noise inside a building, The steps include detecting the sound inside the room, A step of determining the sound source distribution within the room based on the detected sound, The process includes a step of evaluating the ambient sound in the room based on the sound source distribution, The step of evaluating the aforementioned ambient sound is: Based on the aforementioned sound source distribution, the step of calculating the degree of separation, which is a numerical value that scales the degree of dispersion of sound sources, The step includes calculating an evaluation value of the ambient sound based on the degree of separation, A method for evaluating ambient sound in an indoor environment, comprising the step of determining the degree of separation of the sound sources, wherein for each region containing a sound source, the ratio of the number of other regions adjacent to the region containing the sound source that do not contain the sound source to the number of regions adjacent to the region containing the sound source is calculated, and the average value of the ratio for each region containing the sound source is calculated as the degree of separation of the sound sources.

6. The further step involves determining, based on the detected sound, at least one selected from sound pressure, sound quality, and the degree of change of the sound pressure at a predetermined location in the room, The indoor ambient sound evaluation method according to claim 5, wherein in the step of calculating the evaluation value of the ambient sound, the evaluation value is calculated using at least one selected from the sound pressure, sound quality and the degree of change of the sound pressure, in addition to the degree of separation of the sound source.

7. An indoor environmental sound evaluation device for evaluating the ambient sound inside a building, A sound detection device for detecting sounds in the aforementioned room, The system comprises a computing device configured to determine the sound source distribution in the room based on the sound detected by the sound detection device, and to evaluate the ambient sound in the room based on the sound source distribution. The aforementioned computing device is configured to determine the dominance of the sound sources based on the sound source distribution, and to calculate the evaluation value of the ambient sound based on the dominance of the sound sources. The sound detection device is configured to detect multiple sound pressures propagating from multiple directions of arrival at a predetermined location within the room. The indoor environmental sound evaluation device is configured such that the calculation device identifies the maximum value from among a plurality of sound pressures, calculates the average value of a plurality of differences obtained by subtracting each of the plurality of sound pressures from the maximum value as the excellence of the sound source, and calculates the evaluation value as a better value the smaller the excellence of the sound source.

8. The indoor environmental sound evaluation device according to claim 7, wherein the sound detection device includes an array microphone equipped with a plurality of microphones for detecting the sound pressure from a plurality of incoming directions.

9. An indoor environmental sound evaluation device for evaluating the ambient sound inside a building, A sound detection device for detecting sounds in the aforementioned room, The system comprises a computing device configured to determine the sound source distribution in the room based on the sound detected by the sound detection device, and to evaluate the ambient sound in the room based on the sound source distribution. The aforementioned computing device is configured to calculate a degree of separation, which is a numerical value that scales the degree of dispersion of sound sources, based on the sound source distribution, and to calculate an evaluation value of the ambient sound based on the degree of separation. The aforementioned computing device is configured to calculate, for each region containing a sound source, the ratio of the number of other regions adjacent to the region containing the sound source to the number of regions adjacent to the region containing the sound source, and to calculate the average value of the ratio for each region containing the sound source as the degree of separation of the sound source.

10. The indoor environmental sound evaluation device according to claim 9, wherein the sound detection device includes an array microphone equipped with multiple microphones for detecting sound pressure from multiple directions of arrival.

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