Sixteen female and fifteen male subjects, 19-51 years of age participated in the present study. Its purpose was to determine various combinations of sinusoidal simultaneously presented (dual-axis) vertical and lateral whole-body vibrations that are sensed as equally strong as a preceding single-axis reference (a_w = 1.25 ms~(-2) r.m.s.) which was applied in either of both directions only and which had the same frequency, namely 1.6, 3.15, 6.3 or 12.5 Hz. The test motion consisted of a constant predefined and a variable component. The first was applied in the same direction and with either of 5 predefined percentages of the acceleration of the reference (10, 25, 50, 75, 90 percent). The variable component was perpendicuarly oriented to the first (resp. to the reference); its magnitude was varied by the subjects until the dual-axis test signal was judged as equally strong as the single-axis reference.
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