Sensations, Perception Thresholds and Temporary Threshold Shifts of Whole Body Vibrations in Sitting and Standing Posture

The experiments were conducted to evaluate the subjective experience associated with sinusoidal whole body vibration. Exposures were carried out in vertical (z) direction with the subject placed in upright sitting and standing positions. According to the present results, the vibration perception level is approximately the same for both postures, about 80–90 dB, (re 1 μm/s2 (r.m.s)) when comparing frequencies below 100 Hz. The threshold values were found to be influenced by the body weight, heavy people being more sensitive to whole body vibration in sitting posture, light people being more sensitive to vibrations in standing posture. Furthermore, the present study clearly shows the existence of temporary threshold shifts (TTS) in perception of whole body vibration after 5 minutes of vibration fatigue. If measured c. 30 seconds after the end of the exposure the temporary threshold shifts were in the magnitude of 10 dB.