A method for evaluating water surface fluctuation during bathing

A method has been developed for evaluating water surface fluctuation during bathing. Part of a laser beam reflects specularly on the water surface and its trajectory on the wall reflects the fluctuation of the water surface. The trajectory image sequence is analyzed using an image sequence processing based on spatial filtering. Both frequency and amplitude responses of the new method were inspected using an artificial wave generator. The spectral peak is obtained at the same frequency from the generator. The power of the spectral peak increases in proportion to the voltage of the generator. Heart rate, respiratory rate and activity during bathing were evaluated for healthy subjects (n=10). Results from this method were equal to those from contact methods in rates recorded. The slope of the power spectrum reflects the activity during bathing