MASKING FORE AND AFT VIBRATION UNDER TWO AXIAL WHOLE BODY VIBRATION

Abstract

The existence of masking effects for fore and aft vibration under two axial broadband randomvibrations of seated subjects was investigated. Subjects had to adjust equal level of stimulus sensation. Level of excitation (0.55 m/s2 r.m.s., 1.75 m/s2 r.m.s. and 2.25 m/s2 r.m.s.) and seat backrest position (position K inclined 14° with respect to vertical axis and position S in vertical position without inclination) were varied. Masking Threshold (MT) was determined for r.m.s. head acceleration in fore and aft direction. Sitting position as well as level excitation influenced on masking threshold. Linear regression can be used between MT and level of random excitation. Finally, some indicators explaining this phenomenon are presented.