Temporary threshold shifts (TSSs) in vibrotactile perception produced by continuous vibration and repetitive shocks having one complete cycle of a 100 Hz sine wave and exponential decays. The repetition rate of the cycles was 5, 25, 50, or 100/s, while the root-mean-square (r.m.s.) acceleration measured over exposure of five minutes was held constant (weighted according to British Standard (BS) 6842 and International Standard (ISO) 5349). When exposed to five shocks per second at each of the three frequency-weighted acceleration magnitudes, the subjects developed a small TTS. Exposure to 100 shocks per second (continuous vibration) at each of the three frequency-weighted acceleration magnitudes caused a large TTS, although the total frequency-weighted energy was the same as when exposed to five shocks per second. The results suggest that the equal energy hypothesis underlying BS 6842 and ISO 5349 is inappropriate for the prediction of the TTS produced by repetitive shocks.