EVALUATION METHODS FOR VIBRATION EFFECT

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Perceptional and emotional responses on continuous sinusoidal vibrations characteriz-ed as vibration greatness and unpleasant or unbearable feeling were reported in the pre-vious papers.In this paper, the vibration greatness of three kinds of pulses such as pulsed sinusoidal, damped and built-up vibrations is obtained in comparison with a continuous sinusoidal vibration. The frequency of the continuous sinusoidal vibration is selected to be the same as the fundamental frequency of each pulse. Ten male subjects sitting erect are given the whole body vibration in vertical and horizontal directions and the hand vibration in vertical direction.Durations and fundamental frequencies of the pulsed sinusoidal vibrations are changed between 0.005 and 6 sec, and 2-300 Hz respectively, but their level is maintained constant. The vibration greatness of the pulsed sine waves increases with their dura-tion up to approximately 2 sec in the frequecy range between 2 and 60 Hz. The rate of the increase can be approximated by the straight line with the slope of 7 dB / decade of duration.The vibration greatness of the damped vibration can be evaluated by peak-to-peak amplitude and duration of initial one period of its fundamental frequency.The vibration greatness of the built-up vibration can be estimated by its maximum peak-to-peak amplitude, fundamental frequency and duration corresponding to the am-plitude 1.5 dB below the maximum peak-to-peak amplitude.The perceptional threshold for the pulsed sinusoidal waves is also measured and can be approximated by the line with the same slope as that of the vibration greatness (7 dB / decade of duration).