Threshold of Perception for Whole-Body Seated Vibration

A study was done to measure seated vibration perception thresholds in the vertical, lateral, and longitudinal directions at 2, 4, 8, 16, 32, 64, and 96 Hz. 4 male and 2 female subjects were tested. The testing was done on the Ford Vehicle Vibration Simulator (VVS), using a rigid seat with a backrest. A 3-down, 1-up adaptive Levitt algorithm was employed. Bandlimited noise prompting was done over headphones, with subjects eyes closed during stimuli, eliminating non-vibration cues. Subjects'feet moved with the seat at 2 & 4 Hz, eliminating leg motion cues. Test order was randomized over subjects. Thresholds were near 0.01 m/s/s at low frequency for all axes. This is lower than the literature for vertical, probably due to the moving footrest. Lateral thresholds surpassed 0.04 m/s/s around 32 Hz and then dropped down somewhat. Longitudinal vibration had a lower amplitude peak vs. frequency, probably due to backrest input. Vertical showed a peak at 32 Hz. 96 Hz thresholds were generally lower than the values in the literature.