The vibration discomfort of standing people: Relative importance of fore-and-aft, lateral, and vertical vibration

Few studies have compared the discomfort caused by vibration in different directions, and few have investigated the vibration discomfort of standing people. This study was designed to compare the discomfort experienced by standing people exposed to sinusoidal vibration in the fore-and-aft, lateral, and vertical directions. Using the method of magnitude estimation, 12 subjects estimated the discomfort caused by 4-Hz sinusoidal vibration at 10 different magnitudes. At 4 Hz, subjects were less sensitive to lateral vibration than to fore-and-aft vibration (Ky/Kx = 0.71), and more sensitive to vertical vibration than to horizontal vibration (Kz/Kx = 1.95; Kz/Ky = 2.77). Previous findings showing how the discomfort of standing people depends on the frequency of fore-and-aft, lateral, and vertical vibration were used to define frequency weightings that reflect relative sensitivity to vibration in each direction. The frequency weightings differ from those appropriate for seated people, and differ from the weightings for standing people in current standards that were mostly derived from understanding of the discomfort of seated people.

► Shows how direction of vibration affects the vibration discomfort of standing people.
► Shows vibration discomfort is different in seated and standing people.
► Standards for predicting vibration discomfort of seated and standing people can be improved.