Arousal-level determining apparatus and arousal-level determining method
First Claim
1. An arousal-level determining apparatus comprising:
- a memory; and
a processor coupled to the memory executes a process configured to;
receive heartbeat signals for a subject;
generate heartbeat-interval variation data, which indicates changes in heartbeat intervals, on a basis of the heartbeat signals indicating the subject'"'"'s heartbeats;
apply a plurality of times a band-pass filter, which allows passage of a frequency band of a certain range of frequencies, to the heartbeat-interval variation data, the frequency band being changed for each of the plurality of times, and calculate spectral densities with respect to each frequency band, by overlapping a range of frequencies within a first frequency band of the band-pass filter with a second frequency band of the band-pass filter that is nearest to the first frequency band, to detect peaks respectively of the calculated spectral densities;
identify as a feature point a peak in the calculated spectral densities based on the detected peaks; and
determine the arousal level of the subject on a basis of a spectral density and a frequency of the identified feature point, the arousal level inversely indicating a degree of sleepiness of the subject.
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Abstract
An arousal-level determining apparatus includes a generating unit, a calculating unit, an identifying unit, and a determining unit. The generating unit generates heartbeat-interval variation data, which indicates changes in heartbeat interval, on the basis of heartbeat signals indicating subject'"'"'s heartbeats. The calculating unit applies a band-pass filter, which allows passage of a certain range of frequencies, to each frequency band in the heartbeat-interval variation data while changing the frequency band, and calculates spectral density with respect to each frequency band applied with the band-pass filter. The identifying unit identifies a feature point corresponding to a spectral density peak in the calculated spectral densities in the frequency bands. The determining unit determines subject'"'"'s arousal level on the basis of the identified feature point.
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Citations
8 Claims
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1. An arousal-level determining apparatus comprising:
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a memory; and a processor coupled to the memory executes a process configured to; receive heartbeat signals for a subject; generate heartbeat-interval variation data, which indicates changes in heartbeat intervals, on a basis of the heartbeat signals indicating the subject'"'"'s heartbeats; apply a plurality of times a band-pass filter, which allows passage of a frequency band of a certain range of frequencies, to the heartbeat-interval variation data, the frequency band being changed for each of the plurality of times, and calculate spectral densities with respect to each frequency band, by overlapping a range of frequencies within a first frequency band of the band-pass filter with a second frequency band of the band-pass filter that is nearest to the first frequency band, to detect peaks respectively of the calculated spectral densities; identify as a feature point a peak in the calculated spectral densities based on the detected peaks; and determine the arousal level of the subject on a basis of a spectral density and a frequency of the identified feature point, the arousal level inversely indicating a degree of sleepiness of the subject. - View Dependent Claims (2, 3, 4, 5)
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6. A non-transitory computer-readable recording medium having stored therein an arousal-level determining program causing a computer to execute a process comprising:
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receiving heartbeat signals for a subject; generating heartbeat-interval variation data, which indicates changes in heartbeat intervals, on a basis of the heartbeat signals indicating the subject'"'"'s heartbeats; applying a plurality of times a band-pass filter, which allows passage of a frequency band of a certain range of frequencies, to the heartbeat-interval variation data, the frequency band being changed for each of the plurality of times, and calculating spectral densities with respect to each frequency band, by overlapping a range of frequencies within a first frequency band of the band-pass filter with a second frequency band of the band-pass filter that is nearest to the first frequency band, to detect peaks respectively of the calculated spectral densities; identifying as a feature point a peak in the calculated spectral densities based on the detected peaks; and determining the arousal level of the subject on a basis of a spectral density and a frequency of the identified feature point, the arousal level inversely indicating a degree of sleepiness of the subject.
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7. An arousal-level determining method by a computer, the arousal-level determining method comprising:
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receiving heartbeat signals for a subject; generating heartbeat-interval variation data, which indicates changes in heartbeat intervals, on a basis of the heartbeat signals indicating the subject'"'"'s heartbeats; applying a plurality of times a band-pass filter, which allows passage of a frequency band of a certain range of frequencies, to the heartbeat-interval variation data, the frequency band being changed for each of the plurality of times, and calculating spectral densities with respect to each frequency band, by overlapping a range of frequencies within a first frequency band of the band-pass filter with a second frequency band of the band-pass filter that is nearest to the first frequency band, to detect peaks respectively of the calculated spectral densities; identifying as a feature point a peak in the calculated spectral densities based on the detected peaks; and determining the arousal level of the subject on a basis of a spectral density and a frequency of the identified feature point, the arousal level inversely indicating a degree of sleepiness of the subject.
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8. An arousal-level determining apparatus comprising:
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a processor; and a memory, wherein the processor executes a process comprising; receiving heartbeat signals for a subject; generating heartbeat-interval variation data, which indicates changes in heartbeat intervals, on a basis of the heartbeat signals indicating the subject'"'"'s heartbeats; storing the heartbeat-interval variation data in the memory; applying a plurality of times a band-pass filter, which allows passage of a frequency band of a certain range of frequencies, to the heartbeat-interval variation data in the memory, the frequency band being changed for each of the plurality of times, and calculating spectral densities with respect to each frequency band, by overlapping a range of frequencies within a first frequency band of the band-pass filter with a second frequency band of the band-pass filter that is nearest to the first frequency band, to detect peaks respectively of the calculated spectral densities; identifying as a feature point a peak in the calculated spectral densities based on the detected peaks; and determining the arousal level of the subject on a basis of a spectral density and a frequency of the identified feature point, the arousal level inversely indicating a degree of sleepiness of the subject.
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Specification