摘要 |
A living body is irradiated with a first light beam having a first wavelength and a second light beam having a second wavelength which is different from the first wavelength. The first light beam and the second light beam, which have been reflected or transmitted from the living body, are converted into a first electric signal corresponding to the first wavelength and a second electric signal corresponding to the second wavelength, as the observed pulse data. A light absorbance ratio obtained from the first electric signal and the second electric signal is computed, for each one of frequency ranges dividing an observed frequency band. It is determined that noise is not mixed into the observed pulse wave data in a case where a substantial match exists among light absorbance ratios computed for the respective frequency ranges.
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