Psychophysical comparison of vertical and angular vibrations.

Three psychophysical matching experiments were conducted to compare the perceived intensity of angular vibrations, in roll, pitch or yaw, with the perceived intensity of Z-axis translational vibrations. Seated subjects matched their perceptions of the intensity of Z-axis stimulus vibrations--at six frequencies from 2.5-8 Hz, at each of three intensity levels--by adjusting the intensity of angular response vibrations at the same frequencies. The results showed that the acceleration of the angular matching responses increased significantly as a function of both the frequency and the intensity of the stimulus vibrations. Since the stimuli were chosen from existing Z-axis equal intensity contours, the mean matching responses define equivalent contours for angular vibrations. Determination of relationships between translational and angular vibration is essential for the development of improved vibration exposure criteria applicable to complex vibration environments.