JP7284548B1 - signal output device - Google Patents

Abstract

A signal output device and a signal output method capable of improving the safety of the mother and the fetus during delivery are provided. A signal output device (1) includes a signal acquisition unit that acquires a bioelectric signal from an abdomen (20) of a mother (2); processing and IMODWT (Maximum Overlap Discrete Wavelet Inverse Transform) processing to obtain a first feature signal contained in a first frequency band indicative of the motion characteristics of the uterine muscle 21 of the mother body 2 and a higher frequency than the first frequency band; , a second feature signal included in a second frequency band indicating features relating to the motion of the abdominal muscles 22 of the mother 2, and a second feature signal extracted from the same bioelectric signal by the signal extractor. and a signal output unit that sequentially outputs the first feature signal and the second feature signal in time series. [Selection drawing] Fig. 3

Description

The present invention relates to a signal output device that is worn on the abdomen of a mother for use.

Conventionally, there is known a birth monitoring device for monitoring uterine contraction of the mother's body during delivery. Intrauterine pressure catheters and mechanical strain gauge detectors fixed on the maternal abdomen (lateral labor transducers) have been used to measure uterine contractions; There was a problem in that it was easily affected by body movement and breathing.

Therefore, techniques for measuring uterine contractions non-invasively using skin electrodes placed on the maternal abdomen are being researched. Non-Patent Document 1 explains the contraction of the uterus from the electrophysiological characteristics of the uterus, and states that it is possible to provide intrauterine pressure noninvasively and unrestrictively to the mother's body.

Further, Patent Literature 1 discloses a technique for non-invasively monitoring muscle electrical activity such as uterine movement by applying measurement electrodes on the patient's skin.

Characterization of uterine activity by electrohysterography

Japanese Patent Publication No. 2006-523112

According to the technology disclosed in Patent Literature 1, it is possible to acquire a maternal bioelectrical signal and monitor intrauterine pressure and fetal cardiac activity during delivery. However, in Non-Patent Literature 1 and Patent Literature 1, it is not possible to monitor voluntary anger (straining), which is an important movement of the mother's body during delivery. For this reason, there is a concern that the torture that is not synchronized with the uterine activity is performed, which impedes the placental circulation and places a burden on the mother's body and the fetus.

SUMMARY OF THE INVENTION Accordingly, the present invention has been devised in view of the above-mentioned problems. It is an object of the present invention to provide a signal output device capable of improving safety.

The signal output device in the first invention comprises a signal acquisition unit that acquires a bioelectric signal from the abdomen of a mother, and MODWT (Maximum Overlap Discrete Wavelet Transform) processing on the bioelectric signal acquired by the signal acquisition unit. and IMODWT (Maximum Overlap Discrete Wavelet Inverse Transform) processing, a first feature signal included in a first frequency band indicating features related to the motion of the maternal uterine muscle, and a frequency higher than the first frequency band, a signal extraction unit for sequentially extracting a second feature signal included in a second frequency band indicating features related to the motion of the abdominal muscles of the mother in time series; and a signal output unit for sequentially outputting a first absolute value signal indicating the absolute value of the first characteristic signal and a second absolute value signal indicating the absolute value of the second characteristic signal in time series. characterized by

The signal output device in the second invention is the signal output device in the first invention, further comprising a signal evaluation unit that compares and evaluates the first characteristic signal and the second characteristic signal, wherein the signal evaluation unit includes the first characteristic signal and a second time at which the peak of the second characteristic signal appears.

A signal output device according to a third invention is, in the first invention or the second invention, a first signal envelope indicating the envelope of the first absolute value signal and a second signal indicating the envelope of the second absolute value signal. are sequentially output in chronological order.

According to the first to third inventions, the first feature signal included in the first frequency band indicating the feature relating to the motion of the uterine muscle and the second frequency indicating the feature relating to the motion of the abdominal muscle are obtained from the acquired bioelectrical signal. a second feature signal included in the band and a signal extraction unit for sequentially extracting a second feature signal in time series; a first absolute value signal and a second feature indicating the absolute value of the first feature signal extracted from the same bioelectric signal; and a signal output unit that sequentially outputs a second absolute value signal indicating the absolute value of the signal in time series. Therefore, anger and uterine contractions at the same time can be easily detected. In addition, it is possible to easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to improve the safety of the mother and the fetus during delivery.
Further, according to the first to third inventions, the signal output unit includes a first absolute value signal indicating the absolute value of the first characteristic signal, a second absolute value signal indicating the absolute value of the second characteristic signal, are sequentially output in chronological order. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are uniformly output regardless of the direction of the signal. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother and the fetus during delivery.

In particular, according to the second invention, the signal evaluation unit evaluates the time difference between the first time indicating the time at which the peak of the first feature signal appears and the second time indicating the time at which the peak of the second feature signal appears. further provide. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother and the fetus during delivery.

In particular, according to the third invention, the signal output section outputs the first signal envelope representing the envelope of the first absolute value signal and the second signal envelope representing the envelope of the second absolute value signal . Output sequentially in series. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are output more clearly. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother and the fetus during delivery.

FIG. 1(a) is a schematic diagram showing an example of the configuration of the signal output device 1 according to the first embodiment, and FIG. 1(b) shows an example of the configuration of electrodes externally connected to the signal output device 1. It is a schematic diagram. FIG. 2 is a flow chart showing an example of the operation of the signal output device 1 according to the first embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a mounting method of the signal output device 1 according to the first embodiment. FIG. 4 is a plan view showing an example of a mounting method of the signal output device 1 according to the first embodiment. FIG. 5 is a flow chart showing an example of detailed operation of the signal output device 1 in the first embodiment. FIG. 6 is a schematic diagram showing an example of information associated with the operation of the signal output device 1 in the first embodiment. FIG. 7 is a schematic diagram showing an example of a bioelectrical signal pattern acquired by the operation of the signal output device 1 in the first embodiment. FIG. 8 is a schematic diagram showing an example of a signal obtained by decomposing the bioelectric signal of FIG. 7 into specific frequency bands. FIG. 9 is a schematic diagram showing an example of a signal obtained by synthesizing signals in specific frequency bands among the signals in FIG. FIG. 10 is a schematic diagram showing an example of a signal down-sampled from the signal of FIG. FIG. 11 is a schematic diagram showing an example of a signal obtained by decomposing the signal of FIG. 10 into specific frequency bands. FIG. 12 is a schematic diagram showing an example of a signal obtained by synthesizing signals in specific frequency bands among the signals in FIG. FIG. 13 is a schematic diagram showing an example of a signal obtained by synthesizing a signal in a specific frequency band different from the signal in FIG. 9 from the signal in FIG. 14 is a schematic diagram showing an example of a signal indicating the absolute value of the signal in FIG. 12. FIG. FIG. 15 is a schematic diagram showing an example of a signal indicating the absolute value of the signal in FIG. 13. FIG. 16 is a schematic diagram showing an example of a signal showing the envelope of the signal in FIG. 14. FIG. 17 is a schematic diagram showing an example of a signal showing the envelope of the signal in FIG. 15. FIG. FIG. 18 is a schematic diagram showing an example of the configuration of the signal output device 1 according to the second embodiment. FIG. 19 is a flow chart showing an example of the operation of the signal output device 1 in the second embodiment. FIG. 20 is a flowchart showing an example of detailed operation of the signal output device 1 in the second embodiment. 21A and 21B are schematic diagrams showing an example of an evaluation method of an output signal associated with the operation of the signal output device 1 in the second embodiment. FIG. 22 is a schematic diagram showing an example of the signal processing method of the signal output device 1. As shown in FIG.

Hereinafter, an example of a signal output device as an embodiment of the present invention will be described in detail with reference to the drawings. It should be noted that the configuration in each figure is schematically described for explanation, and for example, the size of each configuration and the comparison of sizes for each configuration may be different from those in the drawings.

(First Embodiment: Signal Output Device 1)
An example of the configuration of the signal output device 1 according to the present embodiment will be described with reference to FIGS. 1 and 22. FIG.

The signal output device 1 is attached to the mother's abdomen during delivery, for example, and acquires bioelectric signals. The signal output device 1 extracts and outputs a signal indicating the action of the maternal abdominal muscle and a signal indicating the action of the uterine muscle from the acquired bioelectric signals. Since these two signals are extracted from the same acquired bioelectrical signal, they respectively indicate the action of the abdominal muscle and the action of the uterine muscle at the same time. Therefore, by using the signal output device 1, it is possible to easily grasp the difference between the movement of the uterine muscle due to the uterine contraction of the mother during delivery and the movement of the abdominal muscle due to anger, without using a plurality of devices. can. In addition, it is possible to obtain real-time information such as whether the movement of the abdominal muscles due to anger is early or late with respect to the movement of the uterine muscles due to uterine contraction, and to what extent. Therefore, the user of the signal output device 1 can try to synchronize the movement of the uterine muscle due to uterine contraction and the movement of the abdominal muscle due to anger, thereby improving the safety of the mother and the fetus during delivery. .

The bioelectric signals acquired by the signal output device 1 are, for example, as shown in FIG. Signals in the fetal electrocardiogram band (20 Hz to 60 Hz), which is the frequency band that indicates activity, signals in the maternal electrocardiogram band (10 Hz to 30 Hz), which is the frequency band that indicates the electrical activity of the maternal heart, and the action of the uterine muscle. It includes a signal in the EMG band (0.45 Hz to 2 Hz), which is the frequency band shown, and environmental noise due to respiration and the like. The signal output device 1 decomposes the acquired bioelectrical signal into predetermined frequency bands and extracts the abdominal electromyogram band signal and the uterine electromyogram band signal, respectively, thereby recognizing the action of the abdominal muscles of the mother's body. and signals indicative of the motion of the uterine muscles can be extracted.

The signal output device 1 includes a housing 10, a signal acquisition section 11, a signal extraction section 12, and a signal output section 13, as shown in FIG. 1(a), for example.

<Case 10>
The housing 10 is externally connected to, for example, a signal acquisition unit 11, and has a signal extraction unit 12 and a signal output unit 13 mounted thereon. The housing 10 may be equipped with a known microcontroller (not shown) in which, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) are integrated. It may function as the signal extraction unit 12 and the signal output unit 13 . At this time, the CPU reads the program stored in the ROM and executes it using the RAM as a work area, thereby realizing the functions of the signal acquisition section 11, the signal extraction section 12, and the signal output section 13. FIG. A DSP (Digital Signal Processor), which excels in processing digital signals, may be used instead of the microcontroller.

Further, the housing 10 may include, for example, an input unit such as a keyboard (not shown) and a display unit such as a display. At this time, the user of the signal output device 1 inputs various control commands and the like through the input unit to cause the signal acquisition unit 11 to acquire the bioelectric signal, and the output result of the signal output unit 13 is displayed on the display unit. You may let If the signal output device 1 is of a touch panel type, for example, an input section and a display section are integrally provided.

<Signal Acquisition Unit 11>
The signal acquisition unit 11 acquires a maternal bioelectric signal from, for example, the mother's abdomen during delivery. In this embodiment, the signal acquisition unit 11 is externally connected to one end of an electrically connectable lead wire, as shown in FIG. 1B, for example. At the other end of the lead wire, there are provided skin attachment electrodes 111 to 114 and an indifferent electrode 110 to be attached to the abdomen of the mother. The signal acquisition unit 11 can acquire bioelectric signals at positions where the respective electrodes 111 to 114 and the indifferent electrode 110 are attached via the respective electrodes 111 to 114, the indifferent electrode 110, and lead wires. . Disposable electrodes of silver/silver chloride, for example, are used as the respective electrodes 111 to 114 and the indifferent electrode 110 . Further, the signal acquisition unit 11 uses a biomagnetic sensor having functions equivalent to the respective electrodes 111 to 114 and the indifferent electrode 110 instead of the respective electrodes 111 to 114 and the indifferent electrode 110 to obtain bioelectric signals. may be obtained.

The signal acquisition unit 11 calculates each differential potential signal including information on the differential potential between each of the active electrodes 111 to 114 and the indifferent electrode 110, and then performs amplification processing and filtering processing on each differential potential signal. Amplification/filter processing unit 115 for acquiring the unipolar induced potential signal of each electrode, A/D conversion unit 116 for digitally converting the unipolar induced potential signal acquired by the amplification/filter processing unit 115, A/D and a montage processing unit 117 for obtaining a bipolar induced potential signal between the respective electrodes 111 to 114 based on the unipolar induced potential signal digitally converted by the conversion unit 116 .

The signal acquired by the signal acquisition unit 11 is stored in the RAM of the housing 10, for example. The signals acquired by the signal acquisition unit 11 are transmitted from the respective electrodes 111 to 114 and the indifferent electrode 110 to the housing 10 via lead wires, and are also transmitted using known wireless communication techniques such as Bluetooth and Wi-Fi. may be transmitted to the housing 10 via the

<Signal extractor 12>
The signal extracting unit 12 extracts, from the signals acquired by the signal acquiring unit 11, a signal included in a frequency band indicating features relating to the motion of the uterine muscle and a signal included in a frequency band indicating features relating to the motion of the abdominal muscles in time series. sequentially extracted. Each frequency band used as an extraction condition is specified based on a program pre-stored in the ROM of the housing 10, for example.

<Signal output unit 13>
The signal output unit 13 outputs the signal extracted by the signal extraction unit 12 . The conversion processing method is specified based on a program stored in the ROM of the housing 10, for example. The signal output unit 13 may output the signal extracted by the signal extraction unit 12 to, for example, a display (not shown) externally connected to the housing 10 .

(First Embodiment: Operation Method of Signal Output Device 1)
An example of the operation method of the signal output device 1 according to the present embodiment will be described with reference to FIGS. 2 to 17. FIG. The signal output device 1 performs operations via a program installed in the signal output device 1, for example.

The operation of the signal output device 1 includes, for example, a signal acquisition step S11, a signal extraction step S12, and a signal output step S13, as shown in FIG. Before the signal acquisition step S11, the electrodes 110 to 114 externally connected to the housing 10 are attached in advance to the abdomen of the mother's body.

<Preparation for Signal Acquisition Step S11>
FIG. 3 is a schematic cross-sectional view showing the abdomen 20 of the mother 2 to which the electrodes 110-114 are attached. The signal output device 1 can acquire a bioelectric signal including a signal indicating features relating to the motion of the uterine muscle 21 and a signal indicating features relating to the motion of the abdominal muscles 22 via the electrodes 110 to 114 .

Moreover, FIG. 4 is a plan view showing the abdomen 20 of the mother 2 to which the signal acquisition unit 11 is attached. Each electrode 110 - 114 is attached to the abdomen 20 of the mother 2 . For example, as shown in FIG. 4, the four electrodes 111, 112, 113, and 114 are attached to each of the electrodes 110 to 114 in each of the four regions obtained by dividing the uterine muscle 21 into upper, lower, left, and right regions. It is installed one by one. 3 and 4, the indifferent electrode 110 is attached at a position on the pubic side of the circumference of the uterine muscle 21, for example.

The reason why the mounting positions of the electrodes 110 to 114 are specified in this way is that while muscle contraction appears strongly at the fundus of the uterus, it tends to be weak at the lower part of the uterus and essentially absent at the cervix. be. In addition, the size of the uterus increases with the number of months of pregnancy, and the fundus of the uterus reaches the upper part of the external oblique muscle around the ninth month of pregnancy. Thus, in order to obtain a signal characteristic of the motion of the uterine muscle 21, the bipolar induced potential between the fundus and the cervix, i. Alternatively, it is necessary to acquire the bipolar induced potential between the Seki electrodes 112 and 113 . Also, in order to obtain a signal that indicates the characteristics of the action of the abdominal muscles 22 associated with maternal anger, it is necessary to obtain a unipolar induction potential, which is the differential potential between the interest electrode 112 and the indifference electrode 110 . Based on the above reasons, the arrangement positions of the electrodes 110 to 114 are determined. In addition, by arranging the electrodes 110 to 114 so as to leave the center of the abdomen 20 open, for example, attachment of a known ultrasonic Doppler heart rate probe or ultrasonic tomographic examination for observing the fetus 3 can be performed. It has the advantage of not interfering with the actual obstetric procedure.

During delivery, the delivery force of the fetus 3 is caused by an increase in intrauterine pressure due to the action of the uterine muscle 21 and an increase in intraabdominal pressure due to the action of the abdominal muscle 22 . As the uterine muscle 21 contracts, the uterine muscle 21 presses the fetus 3 in the direction indicated by the solid line in FIG. 3, for example. The abdominal muscles 22 press the fetus 3 via the uterine muscles in the direction indicated by the dashed dotted line in FIG. Coordination of pressure by the uterine muscle 21 and pressure by the abdominal muscle 22 effectively increases the delivery force of the fetus 3 . Therefore, it is useful for obtaining effective delivery output to obtain information on the operation of intrauterine pressure due to uterine contractions and information on the operation of intraabdominal pressure due to anger in chronological order. This leads to a reduction in the risks associated with childbirth for the mother 2 and the fetus 3.

<Signal acquisition step S11>
The signal acquisition step S11 is performed before the signal extraction step S12 and the signal output step S13, as shown in FIG. 5, for example. In the signal acquisition step S11, the signal acquisition unit 11 acquires a bioelectric signal D11 as shown in FIG. 6, for example. The bioelectrical signal D11 includes, for example, an abdominal wall-induced bioelectrical signal D111.

The signal acquisition unit 11 calculates each differential potential signal, which is the difference between the potential signals acquired from the respective electrodes 111 to 114 and the potential signal acquired from the indifferent electrode 110, for example, and then amplifies/filters the signals. Amplification and filtering are performed via 115 to obtain the unipolar induced potential of each of the electrodes 111-114. As conditions for the amplification process, a known set value used in an electrocardiograph or the like is adopted, and the sensitivity is, for example, 10 μV/mm. The filtering conditions employ well-known set values used in an electrocardiograph or the like, and are, for example, filtering that passes a band with a time constant of 0.35 seconds and a cutoff frequency of 0.45 Hz to 100 Hz.

After that, the signal acquisition unit 11 converts the acquired unipolar induction potentials of the respective electrodes 111 to 114 into digital signals via the A/D conversion unit 116 . A sampling frequency for converting a digital signal is, for example, 360 Hz. Furthermore, the signal acquisition unit 11 performs montage processing via the montage processing unit 117 on the unipolar induced potentials of the respective Seki electrodes 111 to 114 converted into digital signals, and converts the unipolar induced potentials between the Seki electrodes 111 to 114 into digital signals. Get the signal. That is, the signal acquiring unit 11 acquires a total of 10-system signals, including 4-system unipolar induced potential signals and 6-system bipolar induced potential signals, as abdominal wall-induced bioelectrical signals D111.

<<Bioelectric signal D11>>
The bioelectrical signal D11 is one of the bioelectrical signals of the mother's body 2, and includes a signal indicating features related to the motion of the uterine muscle 21 and the abdominal muscle 22. FIG. Here, the bioelectrical signal D11 refers to an electrical signal component, and does not include other signal components such as heartbeat, pulse, etc., generated from within the body due to biological phenomena. As an example of the bioelectrical signal D11, in this embodiment, an abdominal wall-induced bioelectrical signal D111 is obtained.

<<Abdominal wall-induced bioelectrical signal D111>>
The abdominal wall-derived bioelectrical signal D111 refers to a bioelectrical signal derived from the abdominal wall surface of the mother 2, ie, the skin surface on which the electrodes 110 to 114 are attached. Abdominal wall-induced bioelectrical signal D111 is shown, for example, in FIG. These signals include, in addition to signals indicating features related to the movement of the uterine muscle 21 and the abdominal muscle 22, physiological interference such as body movement and respiration of the mother 2, body movement and respiration of the fetus 3, power line interference due to lead wires, etc. Contains a lot of environmental noise. For this reason, as will be described later, it is necessary to remove these noises by extracting frequency bands that indicate features related to the motion of the uterine muscle 21 and the abdominal muscle 22 .

<Signal extraction step S12>
The signal extraction step S12 is performed after the signal acquisition step S11 and before the signal output step S13, as shown in FIG. 5, for example. In the signal extraction step S12, the signal extraction unit 12 extracts an extraction signal D12 from the bioelectric signal D11, as shown in FIG. 6, for example. The extracted signal D12 includes, for example, a primary decomposed signal D121, a primary synthesized signal D122, a sampling signal D123, a secondary decomposed signal D124, a first feature signal D125, and a second feature signal D126.

In the signal extraction step S12, for example, as shown in FIGS. 5 and 6, the signal extraction unit 12 performs abdominal wall-induced bioelectrical signals D111 acquired by the signal acquisition unit 11 using MODWT (Maximum Overlap Discrete Wavelet Transform). Primary decomposition processing is performed for each frequency band to obtain a primary decomposition signal D121 (S121). After that, using IMODWT (Maximum Overlap Discrete Wavelet Inverse Transform), primary synthesis processing of a specific frequency band is performed, and from the primary transformed signal D121, the frequency band indicating the feature related to the motion of the uterine muscle 21 of the mother 2 is The contained primary synthesized signal D122 including the low frequency band is extracted (S122).

The signal extraction unit 12 down-samples the extracted primary combined signal D122 in order to remove the environmental noise component, and obtains a sampled signal D123 (S123). After that, the sampled signal D123 is subjected to secondary decomposition processing for each frequency band using MODWT, obtaining a secondary decomposition signal D124 (S124), performing secondary synthesis processing of a specific frequency band using IMODWT, From the secondary decomposition signal D124, a first feature signal D125 including a first frequency band indicating features relating to the motion of the uterine muscle 21 of the mother 2 is extracted (S125).

In addition, in the signal extraction step S12, the signal extraction unit 12 uses the IMODWT to extract a second feature signal D126 including a second frequency band indicating features relating to the motion of the abdominal muscles 22 of the mother 2 from the primary decomposed signal D121. (S126).

<<extracted signal D12>>
The extracted signal D12 is one of the signal components included in the bioelectric signal D11, and includes a signal decomposed into specific frequency band components and a signal obtained by synthesizing the decomposed signals. The combination of decomposed signals on which the synthesized signal is based is selected to include frequency band components that are characteristic of the motion of the uterine muscle 21 and abdominal muscle 22 . When extracting the decomposed signal itself, the signal may be selected alone. As an example of the extraction signal D12, in the present embodiment, a primary decomposition signal D121 obtained by decomposing the bioelectric signal D11 into specific frequency band components is finally extracted from a frequency band that indicates features related to the movement of the uterine muscle 21. and a second feature signal D126 included in the frequency band indicating features related to the motion of the abdominal muscles 22 are extracted.

<<Primary decomposition signal D121>>
The primary decomposition signal D121 indicates each signal obtained by decomposing the abdominal wall-induced bioelectric signal D111 acquired by the signal acquisition unit 11 into specific frequency band components by the signal extraction unit 12 . For example, as shown in FIG. 8, the primary decomposed signal D121 is decomposed by symlet-4 wavelet transform as multi-resolution data with a sampling frequency of 360 Hz and a signal division hierarchy of 5 levels. In FIG. 8, "Level 1" is the frequency band component of 90 Hz to 180 Hz, "Level 2" is the frequency band component of 43.4 Hz to 93.3 Hz, and "Level 3" is the frequency band of 21.7 Hz to 46.5 Hz. "Level 4" indicates the component in the frequency band of 10.9 Hz to 23.3 Hz, and "Level 5" indicates the component in the frequency band of 5.43 Hz to 11.6 Hz. Note that "Approx" in the figure indicates a low frequency band component lower than Level 5, and indicates a frequency band component of 0.016 Hz to 5.61 Hz.

MODWT, for example, is used as a method for decomposing a specific frequency band component, and IMODWT, for example, is used as a method for synthesizing MODWT. MODWT and IMODWT are non-decimated discrete wavelet transforms and multi-resolution analysis methods used to process signals of arbitrary sample size. In the discrete wavelet transform, a signal is decomposed into high frequency band components and low frequency band components, and the decomposed low frequency band components are further decomposed into high frequency band components and low frequency band components. are equivalent. Since the discrete wavelet transform is a reversible transform, it can be applied to noise removal and the like by processing information once transformed and inversely transforming it. When the waveform of the signal to be extracted can be assumed, the waveform with noise removed can be restored by performing the discrete wavelet transform and the inverse discrete wavelet transform using a mother wavelet close to the waveform. The above-mentioned "symlet-4 wavelet" is a kind of mother wavelet, and is used for analysis of bioelectric signals because it resembles the QRS complex (an example of peak waveforms) of electrocardiographic signals.

Specifically, using the sampled signal as a reference, by generating a group of transform packets that gradually divide the frequency component into smaller and equal intervals, only waveforms similar to the waveform of the mother wavelet are extracted, and high-resolution time-frequency analysis is performed. and signal classification can be implemented. For example, the generated signal is extracted as a waveform with a similar scale obtained by scaling (stretching) or translating (translating) the mother wavelet, so it can be extracted without losing time-axis information. Also, a non-stationary signal can be decomposed and synthesized into different frequency bands (divided into half intervals in the example described above). Therefore, a highly accurate bandpass filter can be configured. By using MODWT and IMODWT, it is possible to sequentially extract the first feature signal D125 and the second feature signal D126 from the abdominal wall-induced biosignal D111 with high frequency resolution in real time and in time series. be.

<<Primary combined signal D122>>
The primary synthesized signal D122 indicates a signal obtained by combining and synthesizing the signals of the primary decomposed signal D121 by the signal extraction unit 12 . The primary combined signal D122 is, for example, the signal shown in FIG. The primary synthesized signal D122 is obtained by selecting the low frequency band component of, for example, "Approx (0.016 Hz to 5.61 Hz)" shown in FIG. It is obtained as a signal containing components in the frequency band of 61 Hz.

Incidentally, when extracting a signal that indicates features related to muscle movement, the sampling frequency is usually set to 1 kHz or higher in order to exclude the electrical signal of the heart. On the other hand, the sampling frequency exemplified in the present invention is set to 360 Hz. A preferable sampling frequency range includes the components of the second frequency band (for example, 29 Hz to 45 Hz and 77 Hz to 88 Hz; see later) that show features related to the movement of the abdominal muscle 22 and the movement of the uterine muscle 21 by one MODWT. As a value that can be decomposed into a component that can be extracted from the first frequency band (0.4 Hz to 4 Hz. See later) that indicates the characteristics of the second frequency band, the upper limit of the second frequency band (88 Hz) and filtering As the upper limit of the frequency band to extract the frequency band 88 Hz to 100 Hz between the upper limit (100 Hz) of the cutoff frequency, which is the condition, and the division interval of the frequency band by MODWT as 2 ^-1 times, the frequency band ²ⁿ times (n is a natural number) is preferable, and for example, the lower limit is preferably 176 Hz to 200 Hz or more, which is twice the frequency band. In addition, since the present invention requires real-time output of each signal, the sampling frequency is preferably lower than the normal sampling frequency of 1 kHz in order to reduce the amount of data to be processed. 352 Hz to 400 Hz or less, which is four times the frequency band, is preferable. For the above reasons, in the signal acquisition step S11, the sampling frequency at the time of conversion to a digital signal is preferably 176 Hz or more and 400 Hz ^or less, for example, 176 Hz or more and 400 Hz or less, or 176 Hz or more and 200 Hz or less, or 352 Hz or more and 400 Hz or less are more preferable.

<<Sampling signal D123>>
The sampling signal D123 indicates a signal obtained by down-sampling the primary combined signal D122 by the signal extraction unit 12 . The sampling signal D123 is, for example, the signal shown in FIG. The sampling signal D123 is obtained by down-sampling the primary synthesized signal D122 at a sampling frequency of 30 Hz, for example, as a suitable scale for classifying signals into a frequency band of approximately 0.45 Hz or less and a frequency band higher than that. get. In this case, by performing secondary decomposition processing using MODWT and secondary synthesis processing using IMODWT on the sampling signal D123, the signal in the low frequency band (0.016 Hz to 5.61 Hz) is converted to 2 and a signal with environmental noise removed such as physiological interference such as the frequency band (0.20 Hz to 0.34 Hz) characteristic of respiration of the fetus 3 can be obtained. In the present embodiment, since the frequency band representing the respiration characteristics of the mother 2 and the fetus 3 is included in the low frequency band component of "Approx" in the secondary decomposition signal D124 described later, "Approx" is excluded. By combining the signals, the environmental noise can be removed.

<<Secondary decomposition signal D124>>
The secondary decomposed signal D124 indicates each signal obtained by further decomposing the sampling signal D123 into specific frequency band components by the signal extraction unit 12 . The secondary decomposed signal D124 is decomposed by symlet-4 wavelet transform as multi-resolution data with a sampling signal frequency of 30 Hz and 5 levels, as shown in FIG. 11, for example. In FIG. 11, "Level 1" is the frequency band component from 7.5 Hz to 15 Hz, "Level 2" is the frequency band component from 3.62 Hz to 7.78 Hz, and "Level 3" is from 1.81 Hz to 3.88 Hz. "Level 4" indicates a frequency band component of 0.905 Hz to 1.94 Hz, and "Level 5" indicates a frequency band component of 0.452 Hz to 0.969 Hz. Note that "Approx" in the figure indicates a low frequency band component lower than Level 5, and indicates a frequency band component of 0.016 Hz to 0.485 Hz.

<<first feature signal D125>>
The first feature signal D125 indicates a signal obtained by combining and synthesizing the signals of the secondary decomposed signal D124 by the signal extraction unit 12 . The first characteristic signal D125 is, for example, the signal shown in FIG. The first feature signal D125 is a signal containing components in the frequency band of 0.452 Hz to 1.94 Hz, for example, by selecting "Level 4" and "Level 5" shown in FIG. is obtained as That is, the first feature signal D125 including the first frequency band (0.452 Hz to 1.94 Hz) indicating the motion of the uterine muscle 21 of the mother 2 is acquired. The first characteristic signal D125 can be utilized as an EHG (ElectroHysteroGram: uterine muscle action potential) that indicates the action of the uterine muscle 21, for example.

The relationship between the signals in the first frequency band and the motion of the uterine muscle 21 is described in "Characterization of uterine activity by electrohysterography". The electrical signal that indicates the action of the uterine muscle is composed of two types of waves, slow waves and fast waves, and the fast waves contain information about muscle activity. Also, high-speed waves are classified into a low frequency band and a high frequency band. Electrical signals in the frequency range 0.1 Hz to 0.6 Hz are always present during contractions during both pregnancy and labor, Alvarez waves, also known as uterine hypersensitivity, long-term low-frequency waves (LDBF waves), Contains information about unsteady manual contractions, also called Braxton-Hicks contractions. On the other hand, electrical signals in the frequency range 0.4 Hz to 4 Hz contain information about uterine contractions during labor. That is, it can be said that the first frequency band included in the frequency band of 0.4 Hz to 4 Hz shows the characteristics of the motion of the uterine muscle. Therefore, by extracting the first feature signal D125 included in the first frequency band, it is possible to efficiently acquire information about the motion of the uterine muscle 21 during delivery.

<<second feature signal D126>>
The second feature signal D126 indicates a signal obtained by combining and synthesizing the signals of the primary decomposed signal D121 by the signal extraction unit 12 . The second feature signal D126 is, for example, the signal shown in FIG. The second feature signal D126 is a signal containing components in the frequency band of 21.7 Hz to 93.3 Hz, for example, by selecting "Level 2" and "Level 3" shown in FIG. is obtained as That is, the second feature signal D126 including the second frequency band (21.7 Hz to 93.3 Hz) indicating the motion of the abdominal muscles 22 of the mother 2 is obtained. The second feature signal D126 can be utilized as an EMG (ElectroMyoGram: abdominal muscle action potential) that indicates the action of the abdominal muscle 22, for example. In this embodiment, since the sampling frequency and the frequency component division interval are selected in the signal primary decomposition (S121) in accordance with the second frequency band, the primary synthesized signal D122 including the first feature signal D125 , and the second feature signal D126 can be extracted based on each signal of the primary decomposed signal D121 obtained by one MODWT. In this case, the load on the signal output device 1 due to signal extraction is reduced, and each signal can be output in real time.

The relationship between the signal in the second frequency band and the movement of the abdominal muscles 22 is described in "Study on Maternal Abdominal Body Surface Electromyogram - Its Significance and Clinical Application - (Written by Kunio Nagasawa, Sapporo Medical University)". As a result of observation of MAS-EMG (maternal abdominal body surface electromyography) for 40 first births and 50 paritys, it is reported that about 10 Hz to 110 Hz is effective as the frequency characteristic of MAS-EMG. In addition, it is reported that the central frequencies of the left and right external abdominal oblique muscles with high myoelectric potential are 29 Hz to 45 Hz and 77 Hz to 88 Hz. That is, it can be said that the second frequency band, which is included in the frequency band of 10 Hz to 110 Hz and includes 29 Hz to 45 Hz and 77 Hz to 88 Hz, indicates the feature of abdominal muscle movement. Therefore, by extracting the second feature signal D126 included in the second frequency band, it is possible to efficiently acquire information about the motion of the abdominal muscles 22 during delivery.

<Signal output step S13>
The signal output step S13 is performed after the signal extraction step S12, for example, as shown in FIG. In the signal output step S13, the signal output unit 13, as shown in FIGS. D126 are sequentially output in time series (S131). In this case, anger and uterine contractions at the same time can be easily detected. In addition, it is possible to easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to improve the safety of the mother 2 and the fetus 3 during delivery.

In the signal output step S13, the signal output unit 13 sequentially outputs the processed first feature signal D125 and the processed second feature signal D126 as the processed signal D13 in time series. good too.

When outputting the processed signal D13, for example, a signal processing unit (not shown) mounted on the housing 10 processes the first feature signal D125 extracted by the signal extracting unit 12 by squaring the frequency. Further, the signal processing unit processes the second feature signal D126 extracted by the signal extraction unit 12 by squaring the frequency. After that, the signal output unit 13 sequentially outputs the first feature signal D125 and the second feature signal D126 processed by the signal processing unit in time series. By this processing, the S/N ratio of each signal is improved, and the separation accuracy of signal peaks can be improved. That is, the accuracy of visual determination of the time difference between the peak of the signal of the first feature signal D125 indicating the feature of the motion of the uterine muscle 21 and the peak of the signal of the second feature signal D126 indicating the feature of the motion of the abdominal muscle 22 is can be improved. For this reason, anger can be easily synchronized with uterine contraction. As a result, it is possible to further improve the safety of the mother and the fetus during delivery. In addition, in the case of squaring processing, the peak of each signal is uniformly output regardless of the direction of the signal, similarly to each of the absolute value signals D131 and D132, which will be described later. can be grasped more easily.

Further, the signal processing unit processes the first feature signal D125 extracted by the signal extraction unit 12, for example, as a first absolute value signal D131 indicating the absolute value of the first feature signal D125. Further, the signal processing section processes the second feature signal D126 extracted by the signal extraction section 12 as a second absolute value signal D132 indicating the absolute value of the second feature signal D126. After that, the signal output unit 13 sequentially outputs the first absolute value signal D131 and the second absolute value signal D132 extracted from the same bioelectric signal D11 and processed by the signal processing unit in time series. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are uniformly output regardless of the direction of the signal. In this case, the discrepancy between anger and uterine contraction can be more easily grasped. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

Further, the signal processing unit processes the first feature signal D125 extracted by the signal extraction unit 12, for example, as a first signal envelope D133 representing the envelope of the first feature signal D125. Further, the signal processing unit processes the second feature signal D126 extracted by the signal extraction unit 12, for example, as a second signal envelope D134 representing the envelope of the second feature signal D126. After that, the signal output unit 13 sequentially outputs the first signal envelope D133 and the second absolute value signal D134 extracted from the same bioelectric signal D11 and processed by the signal processing unit in time series. Compared to the feature signals D125 and D126, the signal envelopes D133 and D134 are smoothed in regions other than the signal peaks, making it easier to detect approximate changes in the signals and improving the separation accuracy of the signal peaks. be able to. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are output more clearly. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

<<Processing signal D13>>
The processed signal D13 is a signal obtained by processing the first feature signal D126 or the second feature signal D127. The processed signal D13 includes a first absolute value signal D131, a second absolute value signal D132, a first signal envelope D133, and a second signal envelope D134.

<<first absolute value signal D131>>
The first absolute value signal D131 refers to a signal that indicates the absolute value of the first feature signal D125. As shown in FIG. 12, the first feature signal D125 has a positive and negative potential difference that is reversed depending on the direction of the signal (the direction of the electric field). . Therefore, for example, as shown in FIG. 14, by indicating the absolute value of the first feature signal D125, the phases of the peaks of the signals due to uterine contraction included in the first feature signal D125, which are different in direction, are aligned in one direction. can be made

<<second absolute value signal D132>>
The second absolute value signal D132 refers to a signal that indicates the absolute value of the second feature signal D126. As shown in FIG. 13, the second characteristic signal D126 reverses the polarity of the potential difference depending on the direction of the signal (the direction of the electric field). For example, as shown in FIG. For example, the phases of the peaks in different directions can be aligned in one direction with respect to the peaks of the signal due to anger (abdominal muscle contraction) included in the second feature signal D126.

<<first signal envelope D133>>
The first signal envelope D133 refers to a signal representing, for example, the envelope of the first feature signal D125 or the envelope of the first absolute value signal D131. The first feature signal D125 and the first absolute value signal D131 contain a lot of unnecessary information for determining the peaks of the signals contained therein, and there is room for improvement in visibility and ease of detection. Therefore, by showing the envelope of the first absolute value signal D131 as shown in FIG. 16, for example, the visibility and ease of detection of the peak of the signal due to uterine contraction can be improved. As a method of forming the signal envelope, for example, a smoothing processing method such as low-pass filtering, processing to a moving average value, processing to a moving median value, etc. may be selected as appropriate. It should be noted that the moving median is preferable because it is less susceptible to outliers than the moving average and can well represent the original characteristics of time-series data. Although not shown, even when the first signal envelope D133 indicates the envelope of the first feature signal D125, visibility and ease of detection can be similarly improved.

<<second signal envelope D134>>
The second signal envelope D134 refers to a signal representing, for example, the envelope of the second feature signal D126 or the envelope of the second absolute value signal D132. The second feature signal D126 and the second absolute value signal D132 contain a lot of unnecessary information for determining the peaks of the signals contained therein, and have problems in visibility and ease of detection. Therefore, for example, as shown in FIG. 17, by processing the envelope of the second absolute value signal D132, it is possible to improve the peak visibility and the ease of detection of the signal due to anger (abdominal muscle contraction). The method of forming the signal envelope is the same as that of the first signal envelope D133. Although not shown, the second signal envelope D134 can similarly improve the visibility and the ease of detection even when it represents the envelope of the second feature signal D126.

After executing each step described above, the operation of the signal output device 1 in the present embodiment ends. Note that the signal output device 1 may, for example, repeatedly execute each step described above.

According to the present embodiment, from the acquired bioelectrical signal D11, the first feature signal D125 included in the first frequency band indicating the feature regarding the motion of the uterine muscle 21 and the second frequency indicating the feature regarding the motion of the abdominal muscle 22 A signal extraction unit 12 that sequentially extracts the second feature signal D126 included in the band in time series, and a first feature signal D125 and a second feature signal D126 that are extracted from the same bioelectric signal D11, and extracts the first feature signal D125 and the second feature signal D126. and a signal output unit 13 for sequentially outputting in series. Therefore, anger and uterine contractions at the same time can be easily detected. In addition, it is possible to easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to improve the safety of the mother 2 and the fetus 3 during delivery.

According to this embodiment, the signal output unit 13 outputs the first absolute value signal D131 indicating the absolute value of the first feature signal D125 and the second absolute value signal D132 indicating the absolute value of the second feature signal D126. Output sequentially in chronological order. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are uniformly output regardless of the direction of the signal. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

According to the present embodiment, the signal output unit 13 outputs a first signal envelope D133 representing the envelope of the first feature signal D125 and a second signal envelope D134 representing the envelope of the second feature signal D126. Output sequentially in chronological order. That is, the peak of the signal due to anger and the peak of the signal due to uterine contraction are output more clearly. Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

According to the present embodiment, from the acquired bioelectrical signal D11, the first feature signal D125 included in the first frequency band indicating the feature regarding the motion of the uterine muscle 21 and the second frequency indicating the feature regarding the motion of the abdominal muscle 22 A signal extraction step S12 for sequentially extracting the second feature signal D126 included in the band in time series, and a first feature signal D125 and a second feature signal D126 extracted from the same bioelectric signal D11 are extracted in time series. and a signal output step S13 for sequentially outputting in series. Therefore, anger and uterine contractions at the same time can be easily detected. In addition, it is possible to easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to improve the safety of the mother 2 and the fetus 3 during delivery.

(Second embodiment: signal output device 1)
An example of the configuration of the signal output device 1 according to this embodiment will be described with reference to FIG. This embodiment differs from the first embodiment in that the signal output device 1 further includes a signal evaluation unit 14 . Note that descriptions of the same configurations as those described above are omitted.

The signal output device 1 further includes a signal evaluation unit 14 in the housing 10, as shown in FIG. 18, for example. The signal evaluation unit 14 may be mounted in an electronic device such as a known laptop (notebook) PC or desktop PC that is externally connected to the housing 10 instead of being mounted in the housing 10 .

<Case 10>
For example, the signal evaluation unit 14 is mounted on the housing 10 . The housing 10 may have, for example, a microcontroller mounted thereon function as the signal evaluation unit 14 . At this time, the CPU reads out the program stored in the ROM and executes it using the RAM as a work area, thereby realizing the function of the signal evaluation section 14 .

<Signal evaluation unit 14>
The signal evaluation unit 14 compares and evaluates the signals output by the signal output unit 13 . The signal evaluation unit 14 outputs, for example, the time at which the peak of the signal included in the frequency band indicating the feature relating to the motion of the uterine muscle 21, which is output by the signal output unit 13, and the frequency band indicating the feature relating to the motion of the abdominal muscle 22. Evaluate the time difference between the time when the signal peak appears. The signal evaluation unit 14 outputs, for example, the evaluation result of the time difference. The output content of the evaluation result may be, for example, quantitative information specifying the time difference, or qualitative information specifying the degree of the time difference in several stages (good, acceptable, unsatisfactory, etc.).

(Second Embodiment: Operation Method of Signal Output Device 1)
An example of the operation method of the signal output device 1 according to the present embodiment will be described with reference to FIGS. 19 to 21. FIG.

The operation of the signal output device 1 further includes a signal evaluation step S14, as shown in FIG. 19, for example.

<Signal evaluation step S14>
The signal evaluation step S14 is performed after the signal output step S13, for example, as shown in FIG. In the signal evaluation step S14, the signal evaluation unit 14 detects respective peaks of the first feature signal D125 and the second feature signal D126 output by the signal output unit 13, for example, and compares the time difference between the peaks (S141 ). After that, the signal evaluation unit 14 outputs the evaluation result of the time difference of each peak (S142).

A known real-time QRS detection system, which is installed in advance in the housing 10 in which the signal evaluation unit 14 is mounted or an externally connected device in the housing 10 in which the signal evaluation unit 14 is mounted, is used for the peak detection method of each signal, for example. For example, the Pan-Tompkins (PT) algorithm is used.

FIG. 21 shows the peak of a first signal envelope D133 indicating the envelope of the first absolute value signal D131 and the peak of a second signal envelope D134 indicating the envelope of the second absolute value signal D132 in the signal evaluation unit 14. shows an example of detection and comparison of The first time t a indicating the time when the peak of the first signal envelope D133 appears is shown as t _a -1, t _a -2, _and t _a -3, respectively. Second times _tb indicating times when the peak of the second signal envelope D134 appears are indicated as tb _- 1, tb _- 2, and tb _- 3, respectively. At this time, the time differences T between the first time _ta and the second time _tb are indicated as Ta, _{Tb ,} and _Tc , respectively. That is, the signal evaluation unit 14 calculates the time difference T between a first time t a indicating the time at which the peak of the first feature signal D125 appears _and a second time t _a indicating the time at which the peak of the second feature signal appears. evaluate. In this case, the discrepancy between anger and uterine contraction can be more easily grasped. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

The first time _ta and the second time _tb are obtained by the signal output device 1 acquiring the current time when the bioelectrical signal D11 is acquired by the signal acquisition unit 11, and the signal output unit 13 acquires The current time and each feature signal D125, D126 are linked and output, and the signal evaluation unit 14 specifies the current time linked to each feature signal D125, D126 at the time when the peak appears. may be The first time t _a and the second time t _b are the current times at which the signal output device 1 outputs the feature signals D125 and D126 continuously output by the signal output unit 13, and The signal output unit 13 associates the current time with each of the feature signals D125 and D126 and outputs them. You may specify by the method to specify. Also, the first time _ta and the second time _tb may be specified using the operation start time of the signal output device 1 as a starting point instead of the current time.

For convenience of explanation, FIG. 21 shows a first signal envelope D133 representing the envelope of the first absolute value signal D131 as a signal from which information equivalent to EHG can be obtained, and Although the example in which the second signal envelopes D134 are compared with each other is described, the present invention is not limited to this. The signal evaluation unit 14 indicates, for example, the combination of the first feature signal D125 and the second feature signal D126, the combination of the first absolute value signal D131 and the second absolute value signal D132, or the envelope of the first feature signal D125. The time difference T may be evaluated using a combination of the first signal envelope D133 and the second signal envelope D134 representing the envelope of the second feature signal D126.

According to the present embodiment, the time difference T between the first time t _a indicating the time at which the peak of the first feature signal D125 appears and the second time t _a indicating the time at which the peak of the second feature signal appears is evaluated. It further includes a signal evaluation unit 14 that performs Therefore, it is possible to more easily grasp the difference between the anger and the contraction of the uterus. As a result, it is possible to further improve the safety of the mother 2 and the fetus 3 during delivery.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1 signal output device 10 housing 11 signal acquisition unit 110 indifferent electrode 111 to 114 interest electrode 12 signal extraction unit 13 signal output unit 14 signal evaluation unit 2 maternal body 20 abdomen 21 uterine muscle 22 abdominal muscle 23 abdominal cavity 3 fetus S11 signal acquisition step S12 signal extraction step S13 signal output step S14 signal evaluation step D11 bioelectric signal D111 abdominal wall derived bioelectric signal D12 extraction signal D121 primary decomposition signal D122 primary combined signal D123 sampling signal D124 secondary decomposition signal D125 first feature signal D126 second Characteristic signal D13 Processed signal D131 First absolute value signal D132 Second absolute value signal D133 First signal envelope D134 Second signal envelope ta First time _{t b Second} time T Time difference

Claims (3)

a signal acquisition unit that acquires a bioelectric signal from the mother's abdomen;
MODWT (Maximum Overlap Discrete Wavelet Transform) processing and IMODWT (Maximum Overlap Discrete Wavelet Inverse Transform) processing are performed on the bioelectrical signal acquired by the signal acquisition unit, and characteristics relating to the motion of the maternal uterine muscle are obtained. and a second feature signal included in a second frequency band having a frequency higher than that of the first frequency band and indicating a feature related to the action of the abdominal muscles of the mother's body, a signal extraction unit that sequentially extracts in time series;
A first absolute value signal indicating the absolute value of the first feature signal and a second absolute value signal indicating the absolute value of the second feature signal extracted from the same bioelectric signal by the signal extracting unit are extracted at a time. a signal output unit that sequentially outputs in series;
A signal output device comprising: further comprising a signal evaluation unit that compares and evaluates the first feature signal and the second feature signal;
The signal evaluation unit evaluates a time difference between a first time when the peak of the first feature signal appears and a second time when the peak of the second feature signal appears. The signal output device according to claim 1. The signal output unit sequentially outputs a first signal envelope indicating the envelope of the first absolute value signal and a second signal envelope indicating the envelope of the second absolute value signal in time series. 3. The signal output device according to claim 1 or 2, characterized by:

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