Abstract
The purpose of this study is to examine the condition of "comfortable swinging". The swinging of the low frequency seems to be sensed in the semicircular canals which sense the posture. Therefore, an equipment is developed for measuring the three-axial acceleration on the ear where is near the semicircular canals. Then, acceleration on the ear of person swung by the active swing chair realizing the comfortable swing and by the active rocking chair changing the driving force with heartbeat fluctuation is measured. It is clarified that the power spectrum of the envelope of acceleration waveform shows the relationship of "1/f". Next, the acceleration on the ear of person riding a pickup truck with hard suspension, comfortable car with soft suspension and comfortable limited express train is measured. The deference between the power spectrum of the envelope of acceleration sensed comfortable and one sensed uncomfortable is clarified.
