EVALUATION METHODS FOR VIBRATION EFFECTS:PART 2. MEASUREMENT OF EQUAL SENSATION LEVEL FOR WHOLE BODY BETWEEN VERTICAL AND HORIZONTAL SINUSOIDAL VIBRATIONS

The sensation of horizontal vibration was equated to that of vertical vibration of the same frequency at 5, 10, 20, 30, 60, 100, 200 and 300 c/s. The sensation of vertical vibration above 5 c/s was found to be stronger than that of horizontal vibration by 10 dB for sitting and by 13 dB for standing. Then, the horizontal vibrations from 0.5 to 200 c/s were equated in sensation with the vertical vibration of 20 c/s at 30 dB (vibration acceleration level (VAL)) for sitting alone. The contours obtained in this experiment and the curves of the equal sensation for horizontal vibration on whole body are quite similar with each other except that VAL at the standard frequency (20 c/s) of the latter is larger by 10 dB than that of the former.