Hand transmitted vibration in a simulated industrial task: A psychophysical evaluation.

摘要

Continued occupational exposure to hand transmitted vibration (HTV) has been related to a series of disorders, which have been collectively defined as the hand-arm vibration syndrome (HAVS). Based on existing knowledge, the International Standard Organization has developed a standard for the measurement, evaluation and assessment of HTV, which documents the measurement and reporting methodology, the dose-response relationship, and the weighing filter for the assessment of HTV. Some researchers have emphasized the need for the development of improved weighing functions and dose-response relationships, for which it is vital to undertake further systematic investigations in order to enhance our understanding of HAVS, and to develop effective assessment methodologies, tool designs and workplace ergonomics. This study evaluated the effect that vibration dominant frequency (16 Hz, 31.5 Hz, 63 Hz, and 125 Hz) and vibration vector sum acceleration (3m/s2 and 5 m/s 2) had on human subjective response to hand transmitted vibration. Through a psychophysical methodology extensively used in Ergonomics, the individual’s perception of the physical stress associated with the intermittent operation of a simulated power hand tool was measured in a laboratory setting. During eight 40-minute trials (8 treatments = 4 vibration frequencies x 2 vibration accelerations), sixteen subjects were instructed to adjust the duration of intermittent rest periods in a simulated industrial task in order to find the maximum acceptable pace at which they estimated to be able to work for a normal 8-hour shift, without feeling sore, aching, with uncomfortable numbness in their hands and arms, or unduly fatigued. In addition to the subjects’ adjustment of rest time, their fingertip vibrotactile threshold shift, their maximum isometric grip force shift, and the absorbed power in their fingers were measured in all eight experimental trials. Results of this study indicated that vector sum acceleration had significant effects on selected rest time and digital absorbed power; and that vibration dominant frequency had significant effects on selected rest time, fingertip vibrotactile threshold shift and digital absorbed power. Finally, the dominant frequency of 31.5 Hz appeared to consistently represent the less stressful level for the vibration dominant frequency in this research study.