Perceptional threshold and equal sensation characteristics for random vibrations of1 or 1/3-octave band were determined on the whole body in the vertical and the hori-zontal directions and on the hand in the vertical direction in the frequency range 2-250 Hz. Difference of sensation between the vertical and the horizontal whole bodyrandom vibrations with 1-octave band was examined and it was found out that the sen-sation of the vertical vibration was equalized to that of the horizontal vibration withthe level of 10 dB larger than that of the vertical vibration above 16 Hz.

Then, the vibration greatness value of the random vibration having continuous widefrequency spectrum was measured by subjective experiment and compared with thevalue estimated from each VG value of its frequency component resulting fromanalysis by an 1 or 1/3 octave band filter as,

VG_T=VG_M,1+0.3 ((ΣiVG_{i, 1})-VG_M,1) (1)

VG_T=VG_M,1/3+O.13((ΣiVG_{i, 1/3})-VG_M,1/3) (2)

where VG_T is the vibration greatness value (in VG) of the random vibration, VG_M is the largest VG value in all of the VG_i values, and ΣVG_i is the sum of the VG, values of all bands. The suffix of 1 or 1/3 indicates the data analyzed by the 1 or 1/3 octave band filter. The estimated VG_T values of the random vibrations are in good agreement with the observed ones in both filter bands.