Psychophysical assessment of angular vibration: comparison of vertical and roll vibrations

A psychophysical matching experiment was conducted to compare the perceived intensity of roll vibration with the perceived intensity of Z-axis translational vibration. Seated subjects matched their perceptions of the intensity of Z-axis vibrations by adjusting the intensity of roll vibrations of the same frequency. The Z-axis stimuli were administered at seven frequencies (from 2.5 to 10 Hz) at each of three intensity levels: the 25-min Fatigue-Decreased Proficiency (FDP) level, the 1-hr FDP level, and the 2.5-hr FDP level, as defined in ISO Standard 2631-1974. The results showed that the acceleration of the roll matching response increased significantly as a function of both the intensity and the frequency of the stimulus vibrations. Since the stimuli were chosen from existing Z-axis equal intensity contours, the mean matching responses define equivalent contours of equal intensity for roll vibration. These results provide information on the relationship between Z-axis vibrations measured in translational acceleration units of G and roll vibrations measured in angular acceleration units of rad/s2. The determination of such relationships is essential for the development of improved vibration exposure criteria applicable to complex vibration environments.