Judgment device, judgment system, judgment method, and judgment program

Abstract

The objective is to provide a determination device that can determine whether or not a predetermined event has occurred by detecting sound waves. [Solution] The determination device 1 includes a first sensor that detects a first physical quantity indicating a first sound wave that is oriented in a first direction and includes a band below the low-frequency sound band, a second sensor that detects a second physical quantity indicating a second sound wave that is oriented in a second direction different from the first direction and includes a band below the low-frequency sound band, and a processing device. The processing device includes a signal processing unit that performs predetermined signal processing on first sound wave information indicating the first physical quantity and second sound wave information indicating the second physical quantity, a correction unit that generates correction value information indicating a correction value of the first sound wave by correcting the first sound wave information on which signal processing has been performed using the second sound wave or parameters calculated by the signal processing, a determination unit that determines whether or not a predetermined event has occurred based on the correction value information, and an output unit that outputs an event occurrence signal indicating that an event has occurred when it is determined that an event has occurred.

Description

Technical Field

[0001] The present invention relates to a determination device, a determination system, a determination method, and a determination program.

Background Art

[0002] There is known a technique of detecting an extremely low frequency sound of 1 Hz or more and 20 Hz or less, also referred to as infrasound, indoors, and detecting the indoor state based on the detected extremely low frequency sound. For example, Patent Document 1 describes a technique of determining that a door has been opened and closed indoors when the interval between a pair of extremely low frequency pulses whose sound pressure level exceeds a predetermined level is 60 seconds or less.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the technique described in Patent Document 1 is intended to prevent suicide in a detention facility, it is not easy to detect the extremely low frequency sound caused by the impact vibration wave generated when a person leans their weight on the toilet door in the detention room, when a piece of clothing is hooked on the toilet door to commit a suicidal act also called hanging. In addition to the toilet door that is the detection target, noise reactions such as impact vibration waves generated when the doors of the facility entrance and exit and the warehouse door are opened and closed, and vibrations of ceilings and walls accompanying human walking occur in the detention facility, so it is necessary to accurately determine only the reaction of the detection target from these noise reactions.

[0005] The present invention is made to solve such a problem, and an object thereof is to provide a determination device capable of determining whether or not a predetermined event has occurred by detecting sound waves in a band equal to or lower than the low sound range.

Means for Solving the Problems

[0006] The determination device according to the present invention includes: a first sensor that detects a first physical quantity indicating a first sound wave that is oriented in a first direction and includes a frequency band below the low-frequency sound band, and outputs the detected first physical quantity as a first physical quantity signal; a second sensor that detects a second physical quantity indicating a second sound wave that is oriented in a second direction different from the first direction and includes a frequency band below the low-frequency sound band, and outputs the detected second physical quantity as a second physical quantity signal; and a processing device that receives the first physical quantity signal and the second physical quantity signal as input. The processing device acquires the first physical quantity corresponding to the first physical quantity signal as first physical quantity information, and also acquires the second physical quantity indicating the second physical quantity corresponding to the second physical quantity signal. The system includes an acquisition unit that acquires physical quantity information, a signal processing unit that performs predetermined signal processing on the first physical quantity information and the second physical quantity information to calculate the first sound wave information and the second sound wave information or parameters calculated from the second sound wave information, a correction unit that corrects the first sound wave information calculated by signal processing using the second sound wave or parameters calculated by signal processing to generate a corrected value for the first sound wave as corrected value information, a determination unit that determines whether or not a predetermined event has occurred based on the corrected value information, and an output unit that outputs an event occurrence signal indicating that the event has occurred when it is determined that the event has occurred.

[0007] Furthermore, the determination device according to the present invention further includes a peak detection unit that determines whether the first sound wave has a first peak value which is a peak value equal to or greater than a predetermined peak threshold, and whether the second sound wave has a second peak value which is a peak value equal to or greater than a peak threshold; the signal processing unit calculates a second compensation value obtained by compensating the second sound wave so that the second peak value matches the first peak value as a parameter, generates second compensation value information indicating the calculated second compensation value; and the correction unit preferably generates correction value information by correcting the first sound wave on which signal processing has been performed using the second compensation value.

[0008] Furthermore, in the determination device according to the present invention, it is preferable that the acquisition unit acquires first physical quantity information and second physical quantity information over a predetermined detection period, the signal processing unit performs signal processing on the first physical quantity information and second physical quantity information acquired over the detection period, the peak detection unit determines whether the first sound wave has a first peak value and whether the second sound wave has a second peak value during the detection period, the signal processing unit calculates a second shift value as a parameter obtained by shifting the second sound wave so that the second peak time corresponding to the second peak value matches the first peak time corresponding to the first peak value, generates second shift value information indicating the calculated second shift value, and the correction unit generates correction value information by correcting the first sound wave on which signal processing has been performed using the second shift value.

[0009] Furthermore, the determination device according to the present invention further includes a peak prediction unit that determines whether the first sound wave may have a first peak value and whether the second sound wave may have a second peak value, and the acquisition unit preferably acquires the first physical quantity information and the second physical quantity information over the detection period when the peak prediction unit determines that the first sound wave may have a first peak value, or when the peak prediction unit determines that the second sound wave may have a second peak value.

[0010] Furthermore, in the determination device according to the present invention, the first direction is preferably the direction toward the toilet door of the detention room.

[0011] Furthermore, the determination system according to the present invention includes: a first sensor that detects a first physical quantity indicating a first sound wave that is oriented in a first direction and includes a frequency band below the low-frequency sound band, and outputs the detected first physical quantity as a first physical quantity signal; a second sensor that detects a second physical quantity indicating a second sound wave that is oriented in a second direction different from the first direction and includes a frequency band below the low-frequency sound band, and outputs the detected second physical quantity as a second physical quantity signal; an acquisition unit that detects a first physical quantity corresponding to the first physical quantity signal as first physical quantity information, and acquires a second physical quantity corresponding to the second physical quantity signal as second physical quantity information; and a first The system includes a signal processing unit that performs predetermined signal processing on physical quantity information and second physical quantity information to calculate first sound wave information and second sound wave information or parameters calculated from the second sound wave information; a correction unit that corrects the first sound wave information calculated by signal processing using the second sound wave or parameters calculated by signal processing to generate a corrected value for the first sound wave as corrected value information; a determination unit that determines whether a predetermined event has occurred based on the corrected value information; and an output unit that outputs an event occurrence signal indicating that an event has occurred when it is determined that an event has occurred.

[0012] Furthermore, the determination method according to the present invention acquires first physical quantity information as a first physical quantity indicating a first sound wave including a bandwidth below the low-frequency sound bandwidth detected by a first sensor facing a first direction, and second physical quantity information indicating a second physical quantity including a bandwidth below the low-frequency sound bandwidth detected by a second sensor facing a second direction different from the first direction, performs predetermined signal processing on the first physical quantity information and the second physical quantity information to calculate first sound wave information and second sound wave information or parameters calculated from the second sound wave information, corrects the first sound wave information calculated by signal processing with the second sound wave or parameters calculated by signal processing to generate a corrected value for the first sound wave as corrected value information, determines whether a predetermined event has occurred based on the corrected value information, and outputs an event occurrence signal indicating that the event has occurred when it is determined that the event has occurred. This includes the following.

[0013] Furthermore, the determination program according to the present invention acquires first physical quantity information as a first physical quantity indicating a first sound wave that includes a frequency band below the frequency band of low-frequency sound detected by a first sensor facing a first direction, and second physical quantity information indicating a second physical quantity that includes a frequency band below the frequency band of low-frequency sound detected by a second sensor facing a second direction different from the first direction. The program performs predetermined signal processing on the first physical quantity information and the second physical quantity information to calculate first sound wave information and second sound wave information or parameters calculated from the second sound wave information. The program corrects the first sound wave information calculated by signal processing with the second sound wave or parameters calculated by signal processing to generate a corrected value for the first sound wave as corrected value information. Based on the corrected value information, the program determines whether a predetermined event has occurred, and when it is determined that an event has occurred, the program causes the computer to execute a process to output an event occurrence signal indicating that an event has occurred.

[0014] Furthermore, the determination device according to the present invention includes: a first sensor that detects a signal including a first physical quantity indicating a first sound wave that is oriented in a first direction and includes a band below the low-frequency sound band, and outputs the detected first physical quantity; a second sensor that detects a second physical quantity indicating a second sound wave that is oriented in a second direction different from the first direction and includes a band below the low-frequency sound band, and outputs a signal including the detected second physical quantity; and a processing device to which the first physical quantity and the second physical quantity are input as signals. The processing device includes: a correction unit that performs signal processing based on the input first physical quantity and the second physical quantity and generates correction value information indicating a correction value of the first sound wave by correcting the signal information based on the first physical quantity; a determination unit that determines whether or not a predetermined event has occurred based on the correction value information; and an output unit that outputs an event occurrence signal indicating that an event has occurred when it is determined that an event has occurred. [Effects of the Invention]

[0015] The determination device according to the present invention can determine whether or not a predetermined event has occurred by detecting sound waves in the low-frequency range or lower. [Brief explanation of the drawing]

[0016] [Figure 1] This is a plan view showing a detention facility where the determination device according to the first embodiment is arranged. [Figure 2] (a) is a perspective view of the determination device shown in Figure 1, and (b) is a block diagram of the processing device shown in (a). [Figure 3] This is a diagram showing an example of the intensity of a sound wave detected by the first sensor shown in Figure 2(a). [Figure 4] This is a flowchart of the determination processing executed by the determination device shown in Figure 2(b). [Figure 5] (a) is a perspective view of the determination device according to the second embodiment, and (b) is a block diagram of the processing device shown in (a). [Figure 6] This is a flowchart of the determination processing executed by the determination device shown in Figure 5(b). [Figure 7] (a) is a first diagram for explaining the determination processing executed by the determination device shown in Figure 5(b), (b) is a second diagram for explaining the determination processing executed by the determination device shown in Figure 5(b), and (c) is a third diagram for explaining the determination processing executed by the determination device shown in Figure 5(b). [Figure 8] (a) is a perspective view of the determination device according to the third embodiment, and (b) is a block diagram of the processing device shown in (a). [Figure 9] This is a flowchart of the determination processing executed by the determination device shown in Figure 8(b). [Mode for Carrying Out the Invention]

[0017] The determination device according to the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to these embodiments, and extends to the invention described in the claims and equivalents thereof.

[0018] (Configuration and Functions of the Determination Device According to the First Embodiment) Figure 1 is a plan view showing a detention facility where the determination device according to the first embodiment is arranged.

[0019] The detention cell 100 has a pair of corridors 101, and multiple detention rooms 110, each having a toilet 111 equipped with a toilet door 112, located outside the pair of corridors 101, and is monitored by a supervisor who monitors a monitoring device 120. In addition, the detention cell 100 is equipped with multiple determination devices 1 that determine whether or not a suicide attempt using the toilet door 112 has been made. The detention cell 100 is sealed off from the outside by corridor-end doors 103 located at one end of each of the pair of corridors 101, and has high airtightness. Since the corridor-end doors 103 are located between the highly airtight detention cell 100 and the outside of the detention cell 100, the opening and closing of the corridor-end doors 103 causes fluctuations in air pressure throughout the detention cell 100, generating infrasound. The infrasound associated with the opening and closing of the corridor-end doors 103 is caused by fluctuations in air pressure throughout the detention cell 100, and therefore originates from a wide-area source and is not directional. Furthermore, the sound pressure level of the infrasound generated by the opening and closing of the door 103 at the back of the corridor causes air pressure fluctuations throughout the entire detention cell 100, and is therefore greater than the sound pressure level of the infrasound generated by the suicide act using the toilet door 112.

[0020] Each of the multiple detention cells 110 has a toilet 111. A determination device 1 is placed near the toilet 111. The toilet 111 is separated from the rest of the detention cell 110 by a toilet door 112. The toilet door 112 is located inside the airtight detention cell 100. Since the toilet door 112 is located inside the airtight detention cell 100 and the torque for opening and closing the toilet door 112 is small, the sound pressure level of infrasound associated with opening and closing the toilet door 112 is smaller than the sound pressure level of infrasound associated with suicide using the toilet door 112.

[0021] The upper part of the toilet door 112 is originally designed with a slanted taper to prevent string-like objects from being caught on it. However, if the taper angle of the taper formed at the top of the toilet door 112 is shallow, there is a risk that a typical hanging suicide could be carried out by securing thick clothing to the top of the toilet door 112, which is higher than the suspect's height, and vertically compressing the carotid artery in the suspect's neck. The infrasound associated with suicide using the toilet door 112 is an impact vibration wave generated when an impact load is applied to the rigid body of the toilet door 112 by the suspect's weight, and therefore originates from a localized source and is directional.

[0022] Figure 2(a) is a perspective view of the determination device 1, and Figure 2(b) is a block diagram of the processing device shown in Figure 2(a). In Figure 2(a), electrical wiring is indicated by dashed lines.

[0023] The determination device 1 comprises a housing 10, a first sensor 11, a second sensor 12, and a processing device 20. The first sensor 11 and the second sensor 12 detect infrasound and determine whether or not a suicide attempt has occurred using clothing secured to the toilet door 112.

[0024] The housing 10 is made of a highly rigid material such as metal, has a cylindrical shape, has a first sensor 11 at one end and a second sensor 12 at the other end. The processing device 20 is also arranged inside the housing 10. The housing 10 is fixed to the ceiling of the detention cell 100 (not shown) by, for example, a support member 13, so that the determination device 1 is positioned such that the first sensor 11 faces a first direction toward the toilet door 112, and the second sensor 12 faces a second direction opposite to the toilet door 112.

[0025] The first sensor 11 and the second sensor 12 are pressure sensors that detect the applied pressure, and are arranged in the housing 10 to detect changes in pressure in opposite directions. The first sensor 11 and the second sensor 12 are pressure sensors such as a piezoresistive pressure sensor and a capacitive pressure sensor. The first sensor 11 outputs the first pressure, which is the pressure applied to the first sensor 11, as a first physical quantity signal to the processing unit 20 via the electrical wiring 14. The second sensor 12 outputs the second pressure, which is the pressure applied to the second sensor 12, as a second physical quantity signal to the processing unit 20 via the electrical wiring 14.

[0026] Since the first sensor 11 is directed toward the toilet door 112, it detects the infrasound associated with suicide using the directional toilet door 112 as a change in air pressure applied to the first sensor 11. In addition, the first sensor 11 detects the infrasound associated with the opening and closing of the non-directional door at the end of the corridor 103, as well as the infrasound associated with the vibration of the ceiling of the detention cell 100 due to people walking on the upper floor, as a change in air pressure applied to the first sensor 11. Furthermore, the first sensor 11 detects the infrasound associated with the opening and closing of the toilet door 112, as well as the infrasound associated with the opening and closing of the toilet door 112, as a change in air pressure of the noise level applied to the first sensor 11.

[0027] Since the second sensor 12 faces away from the toilet door 112, it does not detect the infrasound associated with suicide using the toilet door 112, which is generated near the toilet door 112 and is directional. On the other hand, the second sensor 12 detects the infrasound associated with the opening and closing of the non-directional door at the end of the corridor 103, as well as the infrasound associated with the vibration of the ceiling of the detention cell 100 due to people walking on the upper floor, as fluctuations in the air pressure applied to the second sensor 12. Furthermore, the second sensor 12 detects the infrasound associated with the opening and closing of the toilet door 112 as fluctuations in the air pressure of the noise level applied to the second sensor 12.

[0028] Figure 3 shows an example of the intensity of sound waves detected by the first sensor 11. In Figure 3, the horizontal axis represents time, and the vertical axis represents the intensity of sound waves detected by the first sensor 11 in arbitrary units. In Figure 3, peak P1 shows an example of sound waves associated with a suicide attempt using the toilet door 112. Peak P2 shows an example of sound waves associated with the opening of the door 103 at the end of the corridor, and peak P3 shows an example of sound waves associated with the closing of the door 103 at the end of the corridor. Peak P4 shows an example of sound waves associated with vibrations of the ceiling of the detention cell 100.

[0029] The peak value of peak P1, which is a sound wave associated with a suicide using the toilet door 112, is smaller than the peak value of peak P2, which is a sound wave associated with the opening of the door at the back of the corridor 103. However, the peak value of peak P1 is larger than the peak value of peak P3, which is a sound wave associated with the closing of the door at the back of the corridor 103. Furthermore, the peak value of peak P1 is approximately the same as the peak value of peak P4, which is a sound wave associated with the vibration of the ceiling of the detention cell 100. At the same time, the intensity of sound waves detected by the second sensor 12 includes peak P2, which is a sound wave associated with the opening of the door at the back of the corridor 103, peak P3, which is a sound wave associated with the closing of the door at the back of the corridor 103, and peak P4, which is a sound wave associated with the vibration of the ceiling of the detention cell 100, but the peak corresponding to peak P1, which is a sound wave associated with a suicide, is not detected. This is because, as mentioned above, the sound waves associated with suicide originate from a localized source and are directional, and therefore could not be detected by the second sensor 12, which faces a second direction opposite to the toilet door 112.

[0030] The processing unit 20 is configured to comprehensively control the operation of the determination device 1 and comprises one or more processors and their peripheral circuits. For example, the processing unit 20 includes an MPU (Micro Processing Unit). The processing unit 20 may also include a DSP (Digital Signal Processor), LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), etc. The processing unit 20 executes processing based on the program stored in the storage unit 22. The processing unit 20 also controls the operation of each component of the determination device 1 so that the processing is executed appropriately.

[0031] The processing unit 20 includes a communication unit 21, a storage unit 22, and an arithmetic unit 23. The communication unit 21 has predetermined communication interface circuits such as I2C and Serial Peripheral Interface (SPI), and is connected to the first sensor 11, the second sensor 12, and the monitoring device 120 via electrical wiring 14. The communication unit 21 outputs data received from the first sensor 11 and the second sensor 12 to the arithmetic unit 23, and transmits data input from the arithmetic unit 23 to the monitoring device 120.

[0032] The storage unit 22 has semiconductor memory such as ROM or RAM, and stores computer programs and various data for controlling the determination device 1, and inputs and outputs this information to and from the processing unit 23. The computer program may be installed in the storage unit 22 from a computer-readable portable recording medium such as a CD-ROM or DVD-ROM using a known setup program or the like. The computer program may also be stored on a recording medium owned by a predetermined server and installed via a network.

[0033] The processing unit 23 has an arithmetic circuit and performs various signal processing of the determination device 1 based on a computer program stored in the memory unit 22. The processing unit 23 includes an acquisition unit 231, a signal processing unit 232, a correction unit 233, a determination unit 234, and an output unit 235, which are implemented as functional modules of a program that runs on the processor.

[0034] (Determination process performed by the determination device according to the first embodiment) Figure 4 is a flowchart of the determination process performed by the determination device 1. The determination process shown in Figure 4 is performed mainly by the processing unit 20 in cooperation with each element of the determination device 1, based on a determination program stored in the storage unit 22 beforehand. The determination process shown in Figure 4 includes the process performed in the determination method according to the embodiment. The determination process shown in Figure 4 is performed at predetermined determination cycles.

[0035] First, the acquisition unit 231 acquires the first atmospheric pressure detected by the first sensor 11 as first physical quantity information from the first sensor 11 (S101). The first atmospheric pressure is an example of a first physical quantity that represents a first sound wave. The first sensor 11 outputs a first physical quantity signal that represents the applied first atmospheric pressure, and the acquisition unit 231 acquires the first atmospheric pressure corresponding to the first physical quantity signal as first physical quantity information, and stores the acquired first physical quantity information in the storage unit 22 in association with the time of acquisition.

[0036] Next, the acquisition unit 231 acquires second physical quantity information indicating the second atmospheric pressure detected by the second sensor 12 from the second sensor 12 (S102). The second atmospheric pressure is an example of a second physical quantity indicating a second sound wave. The second sensor 12 outputs a second physical quantity signal indicating the applied second atmospheric pressure, the acquisition unit 231 acquires the second atmospheric pressure corresponding to the second physical quantity signal as second physical quantity information, and the storage unit 22 stores the acquired second physical quantity information in association with the time of acquisition.

[0037] Next, the signal processing unit 232 generates a first time-dependent change value, which is the change in the first atmospheric pressure corresponding to the first physical quantity information over time, as the first time-dependent change value information (S103). The signal processing unit 232 acquires the first physical quantity information over a predetermined period stored in the storage unit 22, and generates a first time-dependent change value, which is the atmospheric pressure corresponding to the acquired first physical quantity information arranged in chronological order, as the first time-dependent change value information. The signal processing unit 232 stores the generated first time-dependent change value information in the storage unit 22.

[0038] Next, the signal processing unit 232 generates a second time-dependent change value, which is the time-dependent change of the second atmospheric pressure corresponding to the second physical quantity information, as second time-dependent change value information (S104). The signal processing unit 232 acquires the second physical quantity information over a predetermined period stored in the storage unit 22, and generates a second time-dependent change value, which is the atmospheric pressure corresponding to the acquired second physical quantity information arranged in chronological order, as second time-dependent change value information. The signal processing unit 232 stores the generated second time-dependent change value information in the storage unit 22.

[0039] Next, the signal processing unit 232 generates a first rate of change value as first rate of change value information, which is the rate of change obtained by differentiating the first time-dependent change value corresponding to the first time-dependent change value information generated in the process shown in S103 (S105). The first rate of change value corresponding to the first rate of change value information is first sound wave information calculated from the atmospheric pressure detected by the first sensor 11. The signal processing unit 232 performs a differential operation over the entire first time-dependent change value to calculate the amount of change in the first time-dependent change value in a predetermined unit time, and generates the first rate of change value as first rate of change value information by extracting the envelope of the calculated amount of change in the first time-dependent change value. The signal processing unit 232 stores the generated first rate of change value information in the storage unit 22.

[0040] Next, the signal processing unit 232 generates a second rate of change value as second rate of change value information, which is the rate of change obtained by differentiating the second time-dependent change value corresponding to the second time-dependent change value information generated in the process shown in S104 (S106). The second rate of change value corresponding to the second rate of change value information is second sound wave information calculated from the atmospheric pressure detected by the second sensor 12. The signal processing unit 232 performs a differential operation over the entire second time-dependent change value to calculate the amount of change in the second time-dependent change value in a predetermined unit time, and generates the second rate of change value as second rate of change value information by extracting the envelope of the calculated amount of change in the second time-dependent change value. The signal processing unit 232 stores the generated second rate of change value information in the storage unit 22.

[0041] Next, the correction unit 233 generates a corrected value as corrected value information by correcting the first rate of change value based on the second rate of change value (S107). The correction unit 233 calculates the corrected value by subtracting the second rate of change value corresponding to the second rate of change value information generated in the process shown in S106 from the first rate of change value corresponding to the first rate of change value information generated in the process shown in S105, and stores the calculated corrected value as corrected value information in the storage unit 22.

[0042] Next, the determination unit 234 determines whether the maximum value of the correction value is equal to or greater than a predetermined determination threshold (S108). The determination unit 234 acquires the correction value information stored in the storage unit 22 and extracts the maximum value of the correction value corresponding to the acquired correction value information. The determination unit 234 compares the extracted maximum value of the correction value with the determination threshold corresponding to the determination threshold information stored in the storage unit 22 and determines whether the maximum value of the correction value is equal to or greater than the determination threshold.

[0043] If the determination unit 234 determines that the maximum value of the correction value is equal to or greater than the determination threshold (S108-YES), the output unit 235 outputs an alarm signal to the monitoring device 120 indicating that a suicide using the toilet door 112 has occurred (S109). In response to the alarm signal, the monitoring device 120 displays an image on its display unit indicating that a suicide using the toilet door 112 has occurred, and also emits an alarm sound from its speaker. On the other hand, if the determination unit 234 determines that the maximum value of the correction value is less than the determination threshold (S108-NO), the determination process ends.

[0044] (Effects and effects of the determination device according to the first embodiment) The determination device 1 determines whether a suicide attempt using the toilet door 112 has occurred based on whether the maximum value of the correction value obtained by correcting the first atmospheric pressure detected by the first sensor 11 facing the toilet door 112 based on the second atmospheric pressure detected by the second sensor 12 facing the opposite direction from the toilet door 112 exceeds a threshold. By determining whether a suicide attempt using the toilet door 112 has occurred based on the correction value, the determination device 1 can perform the determination process after eliminating the influence of infrasound associated with the opening and closing operation of the door at the back of the corridor 103, which is detected by both the first sensor 11 and the second sensor 12. By eliminating the influence of infrasound associated with the opening and closing operation of the door at the back of the corridor 103, the determination device 1 can prevent the infrasound associated with the opening and closing operation of the door at the back of the corridor 103 from being mistakenly detected as infrasound associated with a suicide attempt using the toilet door 112. Furthermore, the detection device 1 can prevent the misidentification of infrasound caused by ceiling vibrations as a result of a person walking on the upper floor as infrasound caused by a suicide attempt using the toilet door 112, by eliminating the effects of infrasound caused by ceiling vibrations.

[0045] Furthermore, the determination device 1 can perform the determination process after removing the influence of infrasound noise, which is noise associated with the opening and closing of the toilet door 112, by determining whether or not a suicide act using the toilet door 112 has occurred based on the correction value.

[0046] (Configuration and function of the determination device according to the second embodiment) Figure 5(a) is a perspective view of the determination device according to the second embodiment, and Figure 5(b) is a block diagram of the processing device shown in Figure 5(a). In Figure 5(a), as in Figure 2(a), the electrical wiring 14 is indicated by a dashed line.

[0047] Similar to determination device 1, determination device 2 is positioned in the detention cell 100 with the first sensor 11 facing the toilet door 112, and detects infrasound to determine whether or not a suicide attempt using the toilet door 112 has occurred. Determination device 2 differs from determination device 1 in that it has a processing unit 40 instead of a processing unit 20. The configuration and function of the components of determination device 2 other than the processing unit 40 are the same as those of the components of determination device 1 which are given the same reference numerals, so a detailed explanation is omitted here.

[0048] The processing unit 40 has a communication unit 41, a storage unit 42, and an arithmetic unit 43, and is configured to comprehensively control the operation of the determination device 2. Similar to the processing unit 20, it includes one or more processors and their peripheral circuits. The communication unit 41 and the storage unit 42 have the same configuration and functions as the communication unit 21 and the storage unit 22, so a detailed explanation is omitted here. The arithmetic unit 43 has an arithmetic circuit and performs various signal processing of the determination device 2 based on the computer program stored in the storage unit 42. The arithmetic unit 43 has an acquisition unit 431, a signal processing unit 432, a correction unit 433, a peak detection unit 434, a determination unit 435, and an output unit 436, which are implemented as functional modules of a program that runs on the processor.

[0049] (Determination process performed by the determination device according to the second embodiment) Figure 6 is a flowchart of the determination process performed by the determination device 2. The determination process shown in Figure 6 is performed mainly by the processing unit 40 in cooperation with each element of the determination device 2, based on a determination program stored in the storage unit 42 in advance. The determination process shown in Figure 6 includes the process performed in the determination method according to the embodiment. The determination process shown in Figure 6 is performed at predetermined determination cycles. The processes shown in S201 to S206 performed by the acquisition unit 431 and the signal processing unit 432 are the same as the processes shown in S101 to S106 performed by the acquisition unit 231 and the signal processing unit 232, so a detailed explanation is omitted here.

[0050] Following the process shown in S206, the peak detection unit 434 determines whether the first rate of change value corresponding to the first rate of change value information generated in the process shown in S205 has a first peak value that is equal to or greater than a predetermined peak threshold for determining that the first rate of change value has a first peak value (S207). The peak detection unit 434 extracts a peak value from the first rate of change value corresponding to the first rate of change value information generated in the process shown in S205. The peak detection unit 434 determines whether the peak value extracted from the first rate of change value is equal to or greater than a predetermined peak threshold. If the extracted peak value is equal to or greater than the peak threshold, the peak detection unit 434 determines that the first rate of change value has a first peak value (S207-YES). If the extracted peak value is less than the peak threshold, the peak detection unit 434 determines that the first rate of change value does not have a first peak value (S207-NO).

[0051] If the peak detection unit 434 determines that the first rate of change value does not have a first peak value (S207-NO), the correction unit 433 generates a corrected value as corrected value information by correcting the first rate of change value based on the second rate of change value (S208). Next, the determination unit 435 determines whether the corrected value is equal to or greater than a predetermined determination threshold (S209). If the determination unit 435 determines that the corrected value is equal to or greater than the determination threshold (S209-YES), the output unit 436 outputs an alarm signal to the monitoring device 120 indicating that a suicide using the toilet door 112 has occurred (S210). On the other hand, if the determination unit 435 determines that the corrected value is less than the determination threshold (S209-NO), the determination process ends.

[0052] If the peak detection unit 434 determines that the first rate of change value has a first peak value (S207-YES), it stores the first peak value as first peak value information in the storage unit 42 (S211). Next, the peak detection unit 434 determines whether the second rate of change value corresponding to the second rate of change value information generated in the process shown in S206 has a second peak value that is equal to or greater than the peak threshold (S212). The process shown in S212 is the same as the process shown in S207, so a detailed explanation is omitted here. If the peak detection unit 434 determines that the second rate of change value does not have a second peak value (S212-NO), the determination process proceeds to the process shown in S208.

[0053] If the peak detection unit 434 determines that the second rate of change value has a second peak value (S212-YES), it stores the second peak value as second peak value information in the storage unit 42 (S213). Next, the signal processing unit 432 generates a second compensation value calculated by compensating the second rate of change value so that the second peak value matches the first peak value, as second compensation value information (S214). The second compensation value is an example of a parameter calculated from the second sound wave information. The signal processing unit 432 calculates the multiplier of the second peak value to the first peak value by dividing the first peak value by the second peak value. The signal processing unit 432 calculates the second compensation value by multiplying the second rate of change value by the calculated multiplier, and generates the calculated second compensation value as second compensation value information. The signal processing unit 432 stores the generated second compensation value information in the storage unit 42.

[0054] Next, the correction unit 433 generates a corrected value as corrected value information by correcting the first rate of change value based on the second compensation value (S215). The correction unit 433 calculates the corrected value by subtracting the second compensation value information generated in the process shown in S214 from the first rate of change value corresponding to the first rate of change information generated in the process shown in S205, and stores the calculated corrected value as corrected value information in the storage unit 22. Next, the process proceeds to the determination process shown in S209.

[0055] (Effects and effects of the determination device according to the second embodiment) When the rate of change values ​​of atmospheric pressure detected by the first sensor 11 and the second sensor 12 have peak values ​​equal to or greater than the peak threshold, the determination device 2 calculates a second compensation value by compensating the rate of change value of atmospheric pressure detected by the second sensor 12 so that the peak values ​​of both sensors match. By using the second compensation value calculated so that the peak values ​​of both sensors match, the determination device 2 can execute the determination process after accurately removing the influence of infrasound noise associated with the opening and closing operation of the door 103 at the back of the passage, which is detected by both the first sensor 11 and the second sensor 12. Furthermore, the determination device 2 can execute the determination process after accurately removing the influence of infrasound noise, which is noise associated with the opening and closing of the toilet door 112, etc.

[0056] Figure 7 is a diagram illustrating the judgment process performed by the judgment device 2. In Figures 7(a), 7(b), and 7(c), the horizontal axis represents time, and the vertical axis represents the intensity of the sound wave detected by the first sensor 11 in arbitrary units.

[0057] In Figure 7(a), the dotted line L101 indicates the intensity of the sound wave detected by the first sensor 11, the solid line L102 indicates the intensity of the sound wave detected by the second sensor 12, and the thick line L103 indicates the intensity of the sound wave after the judgment process has been performed. In Figure 7(b), the dotted line L201 indicates the intensity of the sound wave detected by the first sensor 11, the solid line L202 indicates the intensity of the sound wave detected by the second sensor 12, and the thick line L203 indicates the intensity of the sound wave after the judgment process has been performed. In Figure 7(c), the dotted line L301 indicates the intensity of the sound wave detected by the first sensor 11, the solid line L302 indicates the intensity of the sound wave detected by the second sensor 12, and the thick line L303 indicates the intensity of the sound wave after the judgment process has been performed.

[0058] Figure 7(a) shows the sound waves associated with a suicide using the toilet door 112. In the determination process shown in Figure 6, when the determination device 2 determines that the first rate of change value has a first peak value (S207-YES) and the second rate of change value has a second peak value (S212-YES), it generates a second compensation value as second compensation value information by compensating the second rate of change value so that the second peak value matches the first peak value (S214). In this way, noise associated with opening and closing the toilet door 112 is removed from the sound waves detected by the first sensor 11, and the sound waves associated with a suicide using the toilet door 112 can be extracted.

[0059] Figure 7(b) shows the infrasound associated with the opening and closing operation of the door 103 at the back of the corridor. The determination device 2 determines that the first rate of change value does not have a first peak value (S207-NO), thereby removing the infrasound associated with the opening and closing operation of the door 103 at the back of the corridor from the sound waves detected by the first sensor 11, and preventing the infrasound associated with the opening and closing operation of the door 103 at the back of the corridor from being mistakenly detected as sound waves associated with a suicide attempt using the toilet door 112.

[0060] Figure 7(c) shows the infrasound caused by the vibration of the ceiling of the detention cell 100 due to a person walking on the upper floor. The determination device 2 determines that the first rate of change value does not have a first peak value (S207-NO), thereby removing the infrasound caused by the vibration of the ceiling of the detention cell 100 from the sound waves detected by the first sensor 11, and preventing the infrasound caused by the vibration of the ceiling of the detention cell 100 from being mistakenly detected as sound waves associated with a suicide using the toilet door 112.

[0061] (Configuration and function of the determination device according to the third embodiment) Figure 8(a) is a perspective view of the determination device according to the second embodiment, and Figure 8(b) is a block diagram of the processing device shown in Figure 8(a). In Figure 8(a), as in Figure 2(a), the electrical wiring 14 is shown by a dashed line.

[0062] Similar to determination device 1, determination device 3 is positioned in the detention cell 100 with the first sensor 11 facing the toilet door 112, and detects infrasound to determine whether or not a suicide attempt using the toilet door 112 has occurred. Determination device 3 differs from determination device 1 in that it has a processing unit 50 instead of a processing unit 20. The configuration and function of the components of determination device 2 other than the processing unit 50 are the same as those of the components of determination device 1 which are given the same reference numerals, so a detailed explanation is omitted here.

[0063] The processing unit 50 has a communication unit 51, a storage unit 52, and an arithmetic unit 53, and is configured to comprehensively control the operation of the determination device 3. Similar to the processing unit 20, it includes one or more processors and their peripheral circuits. The communication unit 51 and the storage unit 52 have the same configuration and functions as the communication unit 21 and the storage unit 22, so a detailed explanation is omitted here. The arithmetic unit 53 has an arithmetic circuit and performs various signal processing of the determination device 3 based on the computer program stored in the storage unit 52. The arithmetic unit 53 has an acquisition unit 531, a signal processing unit 532, a correction unit 533, a peak prediction unit 534, a peak detection unit 535, a determination unit 536, and an output unit 537, which are implemented as functional modules of a program that runs on the processor.

[0064] (Determination process performed by the determination device according to the third embodiment) Figure 9 is a flowchart of the determination process performed by the determination device 3. The determination process shown in Figure 9 is performed mainly by the processing unit 50 in cooperation with each element of the determination device 3, based on a determination program stored in the storage unit 62 in advance. The determination process shown in Figure 9 includes the process performed in the determination method according to the embodiment. The determination process shown in Figure 9 is performed at predetermined determination cycles. The processes shown in S301 to S306 performed by the acquisition unit 531 and the signal processing unit 532 are the same as the processes shown in S101 to S106 performed by the acquisition unit 231 and the signal processing unit 232, so a detailed explanation is omitted here.

[0065] Following the process shown in S306, the peak prediction unit 534 determines whether the latest rate of change of the first rate of change value corresponding to the first rate of change value information generated in the process shown in S305 is equal to or greater than a predetermined trigger threshold (S307). The peak prediction unit 534 extracts the latest rate of change of the first rate of change value corresponding to the first rate of change value information generated in the process shown in S305. The peak prediction unit 534 determines whether the latest rate of change extracted from the first rate of change value is equal to or greater than a trigger threshold. When the peak prediction unit 534 determines that the latest rate of change of the first rate of change value is equal to or greater than a trigger threshold (S307-YES), the first rate of change value may have a first peak value equal to or greater than the peak threshold.

[0066] The peak prediction unit 534 determines that the latest rate of change of the first rate of change value is less than the trigger threshold (S307-NO), and then determines whether the latest rate of change of the second rate of change value corresponding to the second rate of change value information is greater than or equal to the trigger threshold (S308). The peak prediction unit 534 extracts the latest rate of change of the second rate of change value corresponding to the second rate of change value information generated by the process shown in S306. The peak prediction unit 534 determines whether the latest rate of change extracted from the second rate of change value is greater than or equal to the trigger threshold. When the peak prediction unit 534 determines that the latest rate of change of the second rate of change value is greater than or equal to the trigger threshold (S308-YES), the second rate of change value may have a second peak value greater than or equal to the peak threshold.

[0067] If the peak prediction unit 534 determines that the latest rate of change of the second rate of change value is less than the trigger threshold (S308-NO), the correction unit 533 generates a corrected value as corrected value information by correcting the first rate of change value based on the second rate of change value (S309). Next, the determination unit 536 determines whether the corrected value is greater than or equal to a predetermined determination threshold (S310). If the determination unit 536 determines that the corrected value is greater than or equal to the determination threshold (S310-YES), the output unit 537 outputs an alarm signal to the monitoring device 120 indicating that a suicide using the toilet door 112 has occurred (S311). On the other hand, if the determination unit 536 determines that the corrected value is less than the determination threshold (S310-NO), the determination process ends. Furthermore, if the latest rate of change of the first rate of change value is determined to be less than the trigger threshold (S307-NO) and the latest rate of change of the second rate of change value is determined to be less than the trigger threshold (S308-NO), then neither the first rate of change value nor the second rate of change value will reach the determination threshold, and the processes shown in S309 to S311 may be omitted.

[0068] When the peak prediction unit 534 determines that the latest rate of change of the first rate of change value is equal to or greater than the trigger threshold (S307-YES), the acquisition unit 531 acquires the first atmospheric pressure as the 19th physical quantity information from the first sensor 11 over a predetermined detection period (S312). Also, when the peak prediction unit 534 determines that the latest rate of change of the second rate of change value is equal to or greater than the trigger threshold (S308-YES), the acquisition unit 531 acquires the first atmospheric pressure as the first physical quantity information from the first sensor 11 over a detection period (S312). The detection period during which the acquisition unit 531 acquires the first physical quantity information is, for example, 1 second, and is also called the detection window. The acquisition unit 531 stores the first physical quantity information acquired from the first sensor 11 over the detection period in the storage unit 52 as the first detection information.

[0069] Next, the acquisition unit 531 acquires the second atmospheric pressure as second physical quantity information from the second sensor 12 over the detection period (S313). The acquisition unit 531 stores the second physical quantity information acquired from the second sensor 12 over the detection period in the storage unit 52 as second detection information.

[0070] Next, the signal processing unit 532 generates a first detection change value, which is the change in the first atmospheric pressure over time corresponding to the first detection information, as first detection change value information (S314). Next, the signal processing unit 532 generates a second detection change value, which is the change in the second atmospheric pressure over time corresponding to the second detection information, as first detection change value information (S315). Next, the signal processing unit 532 generates a first detection rate of change value, which is the rate of change obtained by differentiating the first detection change value corresponding to the first detection change value information generated in the process shown in S314, as first detection rate of change value information (S316). Next, the signal processing unit 532 generates a second detection rate of change value, which is the rate of change obtained by differentiating the second detection change value corresponding to the second detection change value information generated in the process shown in S313, as second detection rate of change value information (S317). The processes shown in S314 to S317 are the same as the processes shown in S103 to S106, so a detailed explanation is omitted here.

[0071] Next, the peak detection unit 535 determines whether the first detected rate of change value corresponding to the first detected rate of change value information generated in the process shown in S314 has a first peak value that is equal to or greater than the peak threshold (S318). If the peak detection unit 535 determines that the first detected rate of change value does not have a first peak value that is equal to or greater than the peak threshold (S318-NO), the process proceeds to the process shown in S309.

[0072] If the peak detection unit 535 determines that the first detected rate of change value has a first peak value equal to or greater than the peak threshold (S318-YES), it determines whether the second detected rate of change value corresponding to the second detected rate of change value information has a second peak value equal to or greater than the peak threshold (S319). If the peak detection unit 535 determines that the second detected rate of change value does not have a second peak value equal to or greater than the peak threshold (S319-NO), the process proceeds to the process shown in S309.

[0073] If the peak detection unit 535 determines that the second detected rate of change value is equal to or greater than the peak threshold value (S319-YES), it extracts the first peak time, which corresponds to the first peak value (S320). Next, the peak detection unit 535 stores the first peak value in the storage unit 52 as first peak value information, in association with the first peak time extracted in the process shown in S320 (S321). The peak detection unit 535 extracts the second peak time, which corresponds to the second peak value (S323). Next, the peak detection unit 535 stores the second peak value in the storage unit 52 as second peak value information, in association with the second peak time extracted in the process shown in S321.

[0074] Next, the signal processing unit 532 generates second shift value information, which indicates a second shift value obtained by shifting the time axis of the second detected change value so that the second peak time matches the first peak time (S324). The second shift value is second sound wave information or another example of a parameter calculated from the second sound wave information. The signal processing unit 532 calculates the time difference between the second peak time and the first peak time, shifts the time axis of the second detected change value by the calculated time difference, and compensates the second rate of change value so that the second peak value matches the first peak value to generate second shift value information. The second shift value information generated by shifting the time axis of the second rate of change value so that the second peak value matches the first peak value is stored in the storage unit 52.

[0075] Next, the correction unit 533 generates a corrected value as corrected value information by correcting the first detected change value based on the second shift value (S325). The correction unit 533 calculates the corrected value by subtracting the second shift value information generated in the process shown in S323 from the first detected change value corresponding to the first detected change value information generated in the process shown in S313. The correction unit 533 stores the calculated corrected value as corrected value information in the storage unit 52. Next, the process proceeds to the process shown in S310.

[0076] (Effects and effects of the determination device according to the third embodiment) When the latest rate of change of the first rate of change value and the second rate of change value is greater than or equal to the trigger threshold, the determination device 3 acquires first physical quantity information and second physical quantity information from the first sensor 11 and the second sensor 12 over a detection period also called the detection window. When both the first sensor 11 and the second sensor 12 detect the peak value of the sound wave during the detection period, the determination device 3 shifts the peak value of the sound wave detected by the second sensor 12 to match the peak value of the sound wave detected by the first sensor 11. By matching the peak values ​​of the sound waves detected by the first sensor 11 and the second sensor 12, the determination device 3 can accurately eliminate the effects of ultra-low frequency noise associated with the opening and closing operation of the door 103 at the back of the passage, even if there is a timing difference in detection between the first sensor 11 and the second sensor 12.

[0077] (Modified example of the determination device according to the embodiment) The determination devices 1 to 3 determine whether a suicide attempt has occurred using clothing secured to the toilet door 112. However, the determination device according to the embodiment may also determine whether a predetermined event that generates directional infrasound has occurred and output an event occurrence signal. For example, the determination device according to the embodiment may determine in a nursing home or hospital whether a specific patient has fallen or dropped from a bed while people are coming and going in the surrounding area. Alternatively, the determination device according to the embodiment may determine in a factory or exhibition hall whether a specific monitored object has fallen or been stolen while people are coming and going in the surrounding area.

[0078] Furthermore, while the determination devices 1 to 3 detect infrasound, the determination device according to the embodiment may also detect sound waves that include a frequency band below the low-frequency sound band. For example, the determination device according to the embodiment may detect sound waves that include a frequency band of 50 Hz or less, or it may detect sound waves that include a low-frequency sound band that is 20 Hz or higher and 100 Hz or lower.

[0079] Furthermore, in the judgment devices 1-3, the first and second sensors are arranged to face opposite directions, but they can be positioned in any direction as long as directional infrasound is not mixed into the second sensor. For example, if the housing 10 is a tetrahedron and the opposite direction of the first sensor is defined as 0°, then the sensors should be positioned within a range of ±45°.

[0080] Furthermore, the determination devices 1 to 4 perform all of the determination process and output an alarm signal to the monitoring device 120 indicating that a suicide attempt using the toilet door 112 has occurred. However, the determination devices according to the embodiment do not have to perform all of the determination process. For example, the determination device according to the embodiment may have a first sensor and a second sensor and output a first physical quantity signal and a second physical quantity signal to the monitoring device 120. When the determination device according to the embodiment does not perform all of the determination process, the determination process is performed by the determination system according to the embodiment, which includes the determination device according to the embodiment.

[0081] Furthermore, while the determination devices 1 to 3 have a first sensor 11 and a second sensor 12 which are pressure sensors, the determination device according to the embodiment may have an acoustic sensor instead of the first sensor 11 and the second sensor 12. The determination device according to the embodiment extracts a second infrasound from the sound wave detected by the acoustic sensor, calculates an integral value from the extracted sound wave, and uses the calculated integral value to determine whether or not the sound wave has a peak value. Alternatively, the determination device according to the embodiment may use the calculated integral value to determine whether or not the sound wave has a potential peak value.

[0082] Furthermore, when the determination device 3 determines, using the calculated integral value, that the sound wave may have a peak value, it acquires the first physical quantity information and the second physical quantity information over the detection period. However, the determination device according to the embodiment may acquire the first physical quantity information and the second physical quantity information at predetermined detection cycles over the detection period and determine whether or not the sound wave has a peak value during the acquired detection period.

[0083] Furthermore, in the determination device 3, the signal processing unit 532 shifts the time axis of the second detected change value and compensates the second rate of change value so that the second peak value matches the first peak value to generate second shift value information. However, the determination device according to the embodiment may generate second shift value information by shifting the time axis of the second detected change value without compensating the second rate of change value so that the second peak value matches the first peak value. [Explanation of Symbols]

[0084] 1~3 Judgment device 11. First Sensor 12. Second Sensor 20, 40, 50 Processing Units 231, 431, 531 Acquisition Department 232, 432, 532 Signal Processing Unit 233, 433, 533 Correction section 234, 435, 536 Judgment section 235, 436, 537 Output section 434, 535 Peak detection unit 533 Peak Prediction Unit

Claims

1. A first sensor that detects a first physical quantity that is oriented in a first direction and represents a first sound wave including a frequency band below the low-frequency sound band, and outputs the detected first physical quantity as a first physical quantity signal, A second sensor that detects a second physical quantity that is oriented in a second direction different from the first direction and represents a second sound wave including a frequency band below the low-frequency sound band, and outputs the detected second physical quantity as a second physical quantity signal, The system includes a processing unit to which the first physical quantity signal and the second physical quantity signal are input, and the processing unit is An acquisition unit that acquires the first physical quantity corresponding to the first physical quantity signal as first physical quantity information, and also acquires the second physical quantity corresponding to the second physical quantity signal as second physical quantity information, A signal processing unit that performs predetermined signal processing on the first physical quantity information and the second physical quantity information to calculate the first sound wave information and the second sound wave information or parameters calculated from the second sound wave information, A correction unit generates a correction value for the first sound wave as correction value information by correcting the first sound wave information calculated by the signal processing using the second sound wave information or the parameters calculated by the signal processing, A determination unit that determines whether or not a predetermined event has occurred based on the correction value information, An output unit that outputs an event occurrence signal indicating that the event has occurred when it is determined that the event has occurred, A determination device characterized by having the following features.

2. The system further includes a peak detection unit that determines whether the first sound wave information has a first peak value which is equal to or greater than a predetermined peak threshold, and whether the second sound wave information has a second peak value which is equal to or greater than the peak threshold. The signal processing unit calculates a second compensation value obtained by compensating the second sound wave information so that the second peak value matches the first peak value, and generates the calculated second compensation value as second compensation value information. The determination device according to claim 1, wherein the correction unit generates the correction value information by correcting the first sound wave information on which the signal processing has been performed using the second compensation value.

3. The acquisition unit acquires the first physical quantity information and the second physical quantity information over a predetermined detection period. The signal processing unit performs the signal processing on the first physical quantity information and the second physical quantity information acquired over the detection period. The peak detection unit determines, during the detection period, whether the first sound wave information has a first peak value, and whether the second sound wave information has a second peak value. The signal processing unit calculates a second shift value as the parameter obtained by shifting the second sound wave so that the second peak time corresponding to the second peak value matches the first peak time corresponding to the first peak value, and generates the calculated second shift value as second shift value information. The determination device according to claim 2, wherein the correction unit generates the correction value information by correcting the first sound wave information on which the signal processing has been performed using the second shift value.

4. The system further includes a peak prediction unit that determines whether the first sound wave information may have a first peak value, and whether the second sound wave may have a second peak value. The determination device according to claim 3, wherein the acquisition unit acquires the first physical quantity information and the second physical quantity information over the detection period when the peak prediction unit determines that the first sound wave information may have a first peak value, or when the peak prediction unit determines that the second sound wave information may have a second peak value.

5. The determination device according to any one of claims 1 to 4, wherein the first direction is the direction toward the door of the toilet provided in the detention room.

6. A first sensor that detects a first physical quantity that is oriented in a first direction and represents a first sound wave including a frequency band below the low-frequency sound band, and outputs the detected first physical quantity as a first physical quantity signal, A second sensor that detects a second physical quantity that is oriented in a second direction different from the first direction and represents a second sound wave including a frequency band below the low-frequency sound band, and outputs the detected second physical quantity as a second physical quantity signal, An acquisition unit that detects the first physical quantity corresponding to the first physical quantity signal as first physical quantity information, and acquires the second physical quantity corresponding to the second physical quantity signal as second physical quantity information, A signal processing unit that performs predetermined signal processing on the first physical quantity information and the second physical quantity information to calculate the first sound wave information and the second sound wave information or parameters calculated from the second sound wave information, A correction unit generates a correction value for the first sound wave information as correction value information by correcting the first sound wave information calculated by the signal processing using the second sound wave information or the parameters calculated by the signal processing, A determination unit that determines whether or not a predetermined event has occurred based on the correction value information, An output unit that outputs an event occurrence signal indicating that the event has occurred when it is determined that the event has occurred, A determination system characterized by having the following features.

7. First physical quantity information is obtained as a first physical quantity indicating a first sound wave that includes a frequency band below the frequency band of low-frequency sound detected by a first sensor facing a first direction, and second physical quantity information is obtained as a second physical quantity indicating a second physical quantity that includes a frequency band below the frequency band of low-frequency sound detected by a second sensor facing a second direction different from the first direction. A predetermined signal processing is performed on the first physical quantity information and the second physical quantity information to calculate the first sound wave information and the second sound wave information or the parameters calculated from the second sound wave information. By correcting the first sound wave information calculated by the signal processing using the second sound wave information or the parameters calculated by the signal processing, the corrected value of the first sound wave information is generated as corrected value information. Based on the correction value information, it is determined whether or not a predetermined event has occurred. When it is determined that the aforementioned event has occurred, an event occurrence signal indicating that the aforementioned event has occurred is output. A determination method characterized by including the following.

8. First physical quantity information is obtained as a first physical quantity indicating a first sound wave that includes a frequency band below the frequency band of low-frequency sound detected by a first sensor facing a first direction, and second physical quantity information is obtained as a second physical quantity indicating a second physical quantity that includes a frequency band below the frequency band of low-frequency sound detected by a second sensor facing a second direction different from the first direction. A predetermined signal processing is performed on the first physical quantity information and the second physical quantity information to calculate the first sound wave information and the second sound wave information or the parameters calculated from the second sound wave information, By correcting the first sound wave information calculated by the signal processing using the second sound wave information or the parameters calculated by the signal processing, the corrected value of the first sound wave information is generated as corrected value information. Based on the correction value information, it is determined whether or not a predetermined event has occurred. When it is determined that the aforementioned event has occurred, an event occurrence signal indicating that the aforementioned event has occurred is output. A determination program characterized by having a computer perform the processing.

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