SUBJECTIVE MAGNITUDE OF WHOLE-BODY VIBRATION

Two experiments have been performed to investigate the relation between the level of whole-body vertical a//z vibration and the degree of discomfort it produces. The first experiment, which employed both magnitude estimation and magnitude production methods, suggested that the relation between discomfort, psi , and vibration level, phi , could be adequately expressed in the form psi equals k phi **n. However, the value of n differed greatly between subjects and had a mean value of 1 multiplied by (times) 13 when determined by the method of magnitude estimation and 1. 75 when determined by magnitude production. It is suggested that while the convenient value of unity will sometimes be a sufficient approximation to the value of n the response of a individuals cannot be well approximated by a single value. The second experiment required subjects to adjust the level of a whole-body vibration to correspond to phrases on a four point semantic scale of discomfort. It is shown that the variability in the data obtained by this semantic method is greater than that obtained by comparable numerical scaling methods such as magnitude production and intensity matching.