The frequency dependence of subjective reaction to vertical and horizontal whole-body vibration at low magnitudes

Abstract

The assessment of building vibration with respect to human response requires knowledge of the influence of vibration magnitude, frequency, direction, and duration. This article reports an experiment conducted to investigate the effect of three of these factors: frequency, magnitude, and direction. The method of magnitude estimation was employed with a sound reference stimulus (1/3 octave band centered at 1 kHz) so as to determine reaction to vertical (z-axis) and horizontal (y-axis) sinusoidal whole-body vibration. Twenty subjects were exposed to six acceleration magnitudes in the range 0.04–0.4 ms−2 rms at nine frequencies between 4 and 63 Hz. The relation between magnitude estimate ψ and acceleration magnitude φ was determined at each frequency in the psychophysical power form ψ=kφn. The value of the exponent n varied from 1.04 to 1.47 for vertical motion and from 0.68 to 1.99 for horizontal motion. For vertical motion, the effect of frequency was not significant; for horizontal motion, the exponent increased with increasing frequency. Vibration frequency weightings were determined to describe subjective response to whole-body vibration at low magnitudes that might occur in buildings.