Measurement of human head vibration

Abstract

In order to measure human head vibration, rigid tooth impressions which were closely fitting to the upper central incisors of the subjects were made from acrylic resin. The head vibration was measured with small vibration pickups which had been attached to the tooth impressions. In PART I, three subjects' heads were exposed to a sinusoidal vertical vibration at 15 frequencies in the range of 5 to 125 Hz with a constant acceleration amplitude of 0.08 G (RMS). The head vibration was measured on the tooth impressions and the results were compared with those on the forehead. The measuring method with the tooth impression was found to be highly reproducible. Based on the results, the head was estimated to hava a resonance of between 50 and 80 Hz. In PART II, the transmissibility of three subjects to sinusoidal vertical vibration was assessed on the tooth impressions at 16 frequencies in the range of 3.15 to 100 Hz with a constant acceleration amplitude of 0.1 G (RMS). Measurements of the fore-and-aft (X) and vertical (Z) vibration were made in the sitting and standing postures. The mean transmissibility of the subjects was estimated. In both postures, the mean transmissibility of the subjects showed a peak at 5 Hz, and decreased as the frequency increased from 6.3 Hz. The utility of tooth impressions for the measurement of head vibration is discussed. © 1981, National Institute of Occupational Safety and Health. All rights reserved.