JP3895621B2 - Accident sound detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an accident sound detection apparatus for efficiently detecting only accident sounds from traffic sounds and accident sounds (including accident sounds such as collisions and sudden brake sounds that lead to accidents) at intersections and the like. .
[0002]
[Prior art]
In general, since many traffic accidents occur at intersections, a traffic accident status recording apparatus that records the status of accidents has been conventionally considered.
FIG. 9 is a block diagram showing a conventional traffic accident situation recording apparatus disclosed in, for example, Japanese Patent Laid-Open No. 4-338900.
9, 1 and 4 are traffic lights, 1B, 1Y, 1R, 4B, 4Y, 4R are signal lights, 2B, 2Y, 2R are signal lines, 3 is a signal light blinking device, 5 is a signal light symbol generator, and 6 is a time letter. A generating unit, 7 is an adding unit, 8 is an imaging device, 9 is an endless recording device, 10 is an ambient sound detecting device, 11 is a collision sound detecting circuit, 12 is a recording control device, and 13 is a magnetic recording / reproducing device.
[0003]
Here, the part that detects the accident sound is the ambient sound detection device 10 and the collision sound detection circuit 11. That is, the ambient sound detection device 10 detects an acoustic signal and sends it to the collision sound detection circuit 11. The collision sound detection circuit 11 determines whether or not the detected acoustic signal is a vehicle collision sound. When it is determined as a collision sound, the collision sound detection signal is sent to the recording control device 12.
In the collision sound detection circuit 11, whether or not the detected traffic sound is an accident (collision) sound is compared with the level of the input acoustic signal and a predetermined threshold value, and the level becomes equal to or higher than the threshold value. In the event of an accident. As a countermeasure against malfunction, a directional microphone is used for the ambient sound detection device 10, and a band elimination filter is provided in the path of the acoustic signal.
[0004]
[Problems to be solved by the invention]
By the way, in the collision sound detection circuit described in the above publication, a level comparison is made between an acoustic signal detected in the determination of the collision sound and a preset fixed threshold value. However, in general traffic sounds, there are many sounds with high levels other than accident sounds, such as sudden braking sounds, horn sounds, and runaway sounds. For this reason, the method of comparing the level of the detected acoustic signal with a fixed threshold value has a problem that many traffic sounds are determined as accident sounds in addition to the actual accident sounds.
In addition, there is a problem that information regarding the type of whether the detected accident sound is a collision sound or a sudden braking sound cannot be obtained at all.
[0005]
The present invention was made to solve the above-described problems, and does not use a signal level threshold to determine the accident sound, but calculates the fluctuation of the fundamental frequency of the input accident sound, If the pitch fluctuation is large, it is judged as a siren sound and excluded from the accident sound. This makes it possible to distinguish between sudden braking sound and siren sound, which could not be identified before, and to improve accident sound detection capability. An object is to provide a sound detection device.
[0006]
[Means for Solving the Problems]
An accident sound detection device according to the invention of claim 1 is an accident sound detection device for detecting an accident sound using an external acoustic signal, and the accident sound is obtained as two signals at different times. Obtain the respective fundamental frequencies from the capture means and signals acquired at different times from the accident sound capture means , determine the ratio of the two fundamental frequencies as the pitch fluctuation rate , and determine the magnitude of the pitch fluctuation rate And a pitch fluctuation sound removing means for excluding an output signal having a pitch fluctuation rate larger than a predetermined pitch fluctuation rate from the accident sound, and the accident sound capturing means is externally provided. A waveform shaping circuit for shaping the waveform of the acoustic signal, an A / D converter for converting the analog signal of the waveform shaping circuit into a digital signal, and a difference signal from the output signal from the A / D converter. A difference calculation means, a comparison circuit for comparing a difference signal from the difference calculation means with a reference difference value set in advance, and generating a trigger signal according to the comparison result, and a trigger from the comparison circuit Switch means for taking the output signal from the A / D converter based on the signal into the pitch fluctuation determination calculating means as a plurality of output signals having a predetermined delay time .
[0007]
In the accident sound detection apparatus according to the second aspect of the invention, the accident sound capturing means converts a waveform shaping circuit for shaping the waveform of the external acoustic signal, and converts an analog signal of the waveform shaping circuit into a digital signal. Comparing the A / D converter, the difference calculation means for extracting the difference signal from the output signal from the A / D converter, the difference signal from the difference calculation means and a reference difference value set in advance; A comparison circuit that generates a trigger signal according to the comparison result, and an output signal from the A / D converter based on the trigger signal from the comparison circuit as a plurality of output signals having a predetermined delay time. Switch means to be taken into the pitch fluctuation determination calculation means.
[0008]
According to a third aspect of the present invention, there is provided an accident sound detection device, wherein the pitch fluctuation determination calculating means calculates a plurality of autocorrelation functions for calculating autocorrelation functions from a plurality of output signals acquired from the accident sound capturing means. A plurality of fundamental frequency computing means for calculating a corresponding fundamental frequency based on each autocorrelation function from the plurality of autocorrelation computing means, and A based on each fundamental frequency from the plurality of fundamental frequency computing means And a pitch variation determining means for determining the pitch variation of the output signal from the / D converter.
[0009]
According to a fourth aspect of the present invention, there is provided an accident sound detection apparatus, wherein the pitch variation determination means obtains a pitch variation rate based on each fundamental frequency from the plurality of fundamental frequency calculation units, and the pitch variation rate is smaller than a predetermined value. If it is determined that the sound is an accident sound, and if it is greater than a predetermined value, it is determined that the sound is a pitch fluctuation sound outside the accident sound.
[0010]
According to a fifth aspect of the present invention, there is provided an accident sound detection apparatus comprising: a first switch that captures an output signal from the A / D converter based on a trigger signal from the comparison circuit; And a second switch for taking in an output signal from the A / D converter based on an output signal delayed from the delay circuit for a predetermined time.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a functional block diagram showing Embodiment 1 of the present invention.
In FIG. 1, 20 is an accident sound capturing means, 100 is an acoustic input signal from the ambient sound detection device 10 (see FIG. 9), 110 is an output signal of the accident sound capturing means 20, and 30 is an accident sound capturing means 20. Pitch fluctuation determination calculating means for determining the magnitude of the pitch fluctuation from the output signal 110 from 120, 120 is the output signal of the pitch fluctuation determination calculating means 30, and 40 is an accident sound capture based on the output signal 120 of the pitch fluctuation determination calculating means 30. Pitch fluctuation sound removing means for removing pitch fluctuation sound, for example, siren sound, from the output signal 110 of the means 20, and 130 is an output signal of the pitch fluctuation sound removing means 40.
[0012]
FIG. 2 is a circuit configuration diagram showing an example of a specific circuit configuration of the accident sound capturing means 20.
In FIG. 2, 21 is a waveform shaping circuit for shaping the waveform of the external acoustic input signal 100, 101 is an output signal from the waveform shaping circuit 21, and 22 is an output signal 101 from the waveform shaping circuit 21 that is converted from an analog signal to a digital signal. A is a digital output signal of the A / D converter 22, 23 is a difference calculation means for extracting a difference signal from the digital output signal 102, and 103 is a difference from the difference calculation means 23. 25, a reference difference value generation circuit for generating a difference signal (reference difference value) at a reference level, 24, a difference signal 103 from the difference calculation means 23, and a reference difference value from the reference difference value generation circuit 25 And the trigger signal Trg is generated when the difference signal 103 from the difference calculation means 23 is larger than the set reference difference value. . 26 is a first switch for taking in the output signal 102 of the A / D converter 22 based on the trigger signal Trg from the comparison circuit 24, 111 is an output signal (OUT1) taken in by the switch 26, and 27 is a comparison circuit. A delay circuit that delays the trigger signal Trg from 24 by a predetermined time Δt, 28 is a second switch that captures the output signal 102 of the A / D converter 22 based on the output signal of the delay circuit 27, and 112 is captured by the switch 28. Output signal (OUT2). The switches 26 and 28 and the delay circuit 27 constitute switch means.
[0013]
FIG. 3 is a circuit configuration diagram showing an example of a specific circuit configuration of the pitch variation determination calculation means 30.
In FIG. 3, 31 is an autocorrelation calculating means for calculating the autocorrelation function of the output signal 111 taken by the switch 26, that is, the input signal IN1, and 32 is the fundamental frequency (pitch) f1 of the output signal from the autocorrelation calculating means 31. Similarly, the basic frequency calculation means 33 for calculating, the autocorrelation calculation means 33 for calculating the autocorrelation function of the output signal 112 captured by the switch 28, that is, the input signal IN2, and the basic 34 of the output signal from the autocorrelation calculation means 33. Fundamental frequency calculating means 35 for calculating the frequency (pitch) f2, and 35 is a pitch fluctuation determining means for judging the magnitude of the pitch fluctuation from the basic frequency f1 from the basic frequency calculating means 32 and the basic frequency f2 from the basic frequency calculating means 34. .
[0014]
Next, the operation will be described with reference to FIGS.
Now, when an acoustic input signal 100 is generated and input to the accident sound capturing means 20 when an accident occurs, an unnecessary signal component is removed by the waveform shaping circuit 21 and an output signal 101 is generated.
The output signal 101 is converted from an analog signal to a digital signal 102 by an A / D converter 22. The output digital signal 102 is input to the difference calculation means 23, and the difference signal 103 of the digital output signal 102 is output from the difference calculation means 23. The difference signal 103 generally represents a change in the signal level, and a larger signal level is generated as there is a sudden level change. Conversely, if the level change is small even if the signal level is large, the level is small. Therefore, for example, when a sudden phenomenon occurs such as when an accident occurs, the difference signal 103 shows a large level change. Therefore, a reference difference value as a reference is generated in advance by the reference difference value generation circuit 25, and the difference signal 103 and the reference difference value are compared using the comparison circuit 24. When the difference signal 103 is larger than the reference difference value, it is determined that a traffic accident sound whose signal level changes abruptly is generated, and a trigger signal Trg is generated.
[0015]
The switch 26 is turned on by the trigger signal Trg from the comparison circuit 24, the output signal 102 of the A / D converter 22 is taken in, and the output signal 111 is input to the autocorrelation calculation means 31 of the pitch fluctuation determination calculation means 30. Further, the switch 28 is turned on by the trigger signal Trg from the comparison circuit 24 delayed by the delay circuit 27 by the predetermined time Δt, the output signal 102 of the A / D converter 22 is taken in, and the pitch fluctuation determination calculating means 30 is used as the output signal 112. To the autocorrelation calculating means 33.
[0016]
The autocorrelation calculating means 31 and 33 calculate the autocorrelation function of the input output signals 111 and 112. The spectrumgram of each output signal input to the autocorrelation calculating means 31 and 33 is as shown in FIG. In addition, there are a case where the frequency, that is, the pitch varies with the passage of time, and a case where the frequency, that is, the pitch is constant regardless of the passage of time, as shown in FIG. 4 and 5, the characteristic indicated by the bold line represents the lowest frequency of each output signal, that is, the fundamental frequency f0 (pitch).
Therefore, the autocorrelation calculating means 31 and 33 calculate an autocorrelation function as shown in FIG. Here, the autocorrelation function is a function that is symmetrical with respect to time 0, and repeats peaks and valleys with time in the case of positive time. If the time given to the first peak position by this autocorrelation function is t0, its reciprocal 1 / t0 becomes the fundamental frequency (pitch) f0.
[0017]
The output signals of the autocorrelation calculating means 31 and 33 are supplied to the fundamental frequency calculating means 32 and 34, respectively, and the fundamental frequency (pitch) is obtained from the autocorrelation function as described above. Therefore, the fundamental frequency f1 with the acquisition time t1 is calculated for the output signal 111 acquired by turning on the switch 26 by the trigger signal Trg from the comparison circuit 24, and similarly to the output signal 111 by the delay circuit 27. On the other hand, a basic frequency f2 is calculated for a capture time t2 with respect to the output signal 112 captured by turning on the switch 28 by the trigger signal Trg from the comparison circuit 24 delayed by a predetermined time Δt.
[0018]
FIG. 7 shows the relationship between the fundamental frequencies f1 and f2 computed by the fundamental frequency computing means 32 and 34 at this time. The time t1 is substantially the time when the output signal 111 is captured with respect to the fundamental frequency f1. The time t2 substantially represents the time when the output signal 112 is acquired with respect to the fundamental frequency f2, and the difference between the times t1 and t2 is Δt.
[0019]
In this way, the fundamental frequencies f1 and f2 obtained by the fundamental frequency calculating means 32 and 34 are supplied to the pitch fluctuation determining means 35, where the pitch fluctuation rate rp is obtained. The pitch fluctuation rate rp is calculated from a value obtained by dividing the fundamental frequency f2 by f1, that is, rp = f2 / f1.
[0020]
Next, as shown in FIG. 8, the pitch fluctuation determining means 35 determines whether or not the calculated pitch fluctuation rate rp is larger than a predetermined pitch fluctuation rate Δr, and the pitch fluctuation rate rp is a predetermined pitch fluctuation rate. If it is larger than Δr, it is determined that the signal fetched from the accident sound fetching means 20 to the pitch fluctuation judgment calculating means 30 has pitch fluctuation, that is, a pitch fluctuation sound, and the pitch fluctuation rate rp is greater than the predetermined pitch fluctuation rate Δr. If it is smaller, it is determined that the signal taken from the accident sound capturing means 20 to the pitch fluctuation determination calculating means 30 has no pitch fluctuation, that is, an accident sound, and the determination result is output to the pitch fluctuation sound removing means 40 as an output signal 120. Supply as.
[0021]
In the pitch fluctuation sound removing means 40, when the input output signal 120 is a signal indicating that the pitch fluctuation is large, this is a pitch fluctuation sound, for example, a siren sound, and therefore, the output signal in which the signal component is excluded from the accident sound. 130 is output. Further, in the pitch fluctuation sound removing means 40, if the input output signal 120 is a signal indicating that the pitch fluctuation is small, it is an accident sound. Output as an output signal 130 for a trigger signal.
[0022]
As described above, in the present embodiment, in order to discriminate between a sudden braking sound and a siren sound in an input acoustic signal such as an accident sound, the fluctuation of the fundamental frequency (pitch) is calculated, and the pitch fluctuation is predetermined. If it is larger than the value, it is judged as a siren sound and excluded from the accident sound. If the pitch fluctuation is smaller than the predetermined value, a trigger signal for recording as an accident sound is output. Thus, it is possible to distinguish between the sudden braking sound and the siren sound, and it is possible to efficiently detect only the accident sound and improve the detection ability of the accident sound.
[0023]
【The invention's effect】
As described above, according to the invention of claim 1, there is an accident sound detection device for detecting an accident sound using an external acoustic signal, wherein the accident sound is converted into two signals at different times. Each of the fundamental frequencies is obtained from the accident sound capturing means to be captured and the signals captured at different times from the accident sound capturing means , the ratio of the two fundamental frequencies is determined as the pitch variation rate , and the pitch variation rate Pitch fluctuation determination calculating means for determining magnitude, and pitch fluctuation sound removing means for excluding output signals having a pitch fluctuation rate larger than a predetermined pitch fluctuation rate from the accident sound, the accident sound capturing means, A waveform shaping circuit for shaping the waveform of the external acoustic signal, an A / D converter for converting an analog signal of the waveform shaping circuit into a digital signal, and a differential signal from an output signal from the A / D converter A difference calculating means to be taken out, a comparison circuit for comparing a difference signal from the difference calculating means with a reference difference value set in advance, and generating a trigger signal according to the comparison result, and a trigger from the comparison circuit Switch means for taking the output signal from the A / D converter based on the signal into the pitch fluctuation determination calculation means as a plurality of output signals having a predetermined delay time from each other. Therefore, it is possible to distinguish between sudden braking sound and siren sound, and it is possible to efficiently detect only the accident sound and improve the detection ability of the accident sound.
[0024]
According to a second aspect of the present invention, the accident sound capturing means includes a waveform shaping circuit that shapes the waveform of the external acoustic signal, and an A / A that converts the analog signal of the waveform shaping circuit into a digital signal. The D converter, the difference calculation means for extracting the difference signal from the output signal from the A / D converter, the difference signal from the difference calculation means and the reference difference value set in advance are compared, and the comparison A comparison circuit that generates a trigger signal according to the result, and the pitch fluctuation as a plurality of output signals having a predetermined delay time with respect to the output signal from the A / D converter based on the trigger signal from the comparison circuit Since it has the switch means to be taken into the judgment calculation means, there is an effect that it can contribute to efficiently detecting only the accident sound.
[0025]
According to a third aspect of the present invention, the pitch fluctuation determination calculating means includes a plurality of autocorrelation calculating means for calculating autocorrelation functions from the plurality of output signals acquired from the accident sound capturing means, A plurality of fundamental frequency computing means for calculating a corresponding fundamental frequency based on each autocorrelation function from the plurality of autocorrelation computing means, and the A / D based on each fundamental frequency from the plurality of fundamental frequency computing means Since the pitch variation judging means for judging the pitch variation of the output signal from the converter is provided, it is possible to distinguish between the sudden braking sound and the siren sound and to contribute to the improvement of the detection capability of the accident sound.
[0026]
According to a fourth aspect of the present invention, when the pitch variation determination means obtains a pitch variation rate based on each fundamental frequency from the plurality of fundamental frequency calculation units, and the pitch variation rate is smaller than a predetermined value, If it is determined that the sound is an accident sound and is greater than a predetermined value, it is determined that the sound is a pitch fluctuation sound outside the accident sound, so that the pitch fluctuation of the accident sound can be determined efficiently and reliably.
[0027]
According to a fifth aspect of the invention, the switch means includes a first switch for taking in an output signal from the A / D converter based on a trigger signal from the comparison circuit, and a trigger from the comparison circuit. Since the delay circuit that delays the signal for a predetermined time and the second switch that takes in the output signal from the A / D converter based on the output signal delayed from the delay circuit for the predetermined time, only the accident sound is efficient. There is an effect that it can contribute to detection well.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing a first embodiment of the present invention.
FIG. 2 is a block configuration diagram illustrating an example of an accident sound capturing unit according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram showing an example of pitch fluctuation determination calculation means in the first embodiment of the present invention.
FIG. 4 is a diagram for explaining an operation of an autocorrelation calculating unit according to the first embodiment of the present invention.
FIG. 5 is a diagram for explaining an operation of an autocorrelation calculating unit according to the first embodiment of the present invention.
FIG. 6 is a diagram for explaining an operation of an autocorrelation calculating unit according to the first embodiment of the present invention.
FIG. 7 is a diagram for explaining an operation of a fundamental frequency calculation unit in the first embodiment of the present invention.
FIG. 8 is a diagram for explaining an operation of a pitch variation determination unit according to the first embodiment of the present invention.
FIG. 9 is a block diagram showing a conventional traffic accident situation recording apparatus.
[Explanation of symbols]
20 accident sound capturing means, 21 waveform shaping circuit, 22 A / D converter, 23 difference calculating means, 24 comparing circuit, 25 reference difference value generating circuit, 26, 28 switch, 27 delay circuit, 30 pitch fluctuation determining calculating means 31, 32 Autocorrelation calculating means, 32, 34 Fundamental frequency calculating means, 35 Pitch fluctuation determining means, 40 Pitch fluctuation sound removing means.

Claims (4)

An accident sound detection device for detecting an accident sound using an external acoustic signal,
Accident sound capturing means for capturing the accident sound as two signals at different times ;
Pitch fluctuation determination calculation for obtaining each fundamental frequency from signals taken at different times from the accident sound capturing means, obtaining a ratio of the two fundamental frequencies as a pitch fluctuation rate , and determining the magnitude of the pitch fluctuation rate Means,
Pitch fluctuation sound removing means for excluding an output signal having a pitch fluctuation rate larger than a predetermined pitch fluctuation rate from the accident sound ;
Equipped with a,
The accident sound capturing means includes a waveform shaping circuit that shapes the waveform of the external acoustic signal, an A / D converter that converts an analog signal of the waveform shaping circuit into a digital signal, and the A / D converter. A difference calculating means for extracting a difference signal from an output signal from the comparator, a comparison circuit for comparing the difference signal from the difference calculating means with a reference difference value set in advance and generating a trigger signal according to the comparison result And switch means for taking the output signals from the A / D converter into the pitch fluctuation determination calculating means as a plurality of output signals having a predetermined delay time based on a trigger signal from the comparison circuit. Accident sound detection device characterized by. The pitch fluctuation determination calculating means includes a plurality of autocorrelation calculating means for calculating autocorrelation functions from a plurality of output signals received from the accident sound capturing means, and each self-correlation calculating means from each of the plurality of autocorrelation calculating means. A plurality of fundamental frequency calculating means for calculating a corresponding fundamental frequency based on the correlation function, and determining a pitch variation of the output signal from the A / D converter based on each fundamental frequency from the plurality of fundamental frequency calculating means accident sound detection device according to claim 1, characterized in that it comprises a pitch change determination means for. The pitch variation determination means obtains a pitch variation rate based on each fundamental frequency from the plurality of fundamental frequency calculation units, and determines that the pitch variation sound is outside the accident sound when the pitch variation rate is greater than a predetermined value. The accident sound detection device according to claim 2 . The switch means includes a first switch that captures an output signal from the A / D converter based on a trigger signal from the comparison circuit, a delay circuit that delays the trigger signal from the comparison circuit, and a delay circuit; The accident according to any one of claims 1 to 3 , further comprising a second switch that takes in an output signal from the A / D converter based on an output signal delayed by a predetermined time from the delay circuit. Sound detection device.

Images