"Objective: Temporary threshold shifts (TTSs) of fingertip vibrotactile perception were measured in a laboratory study to examine the effects of handle size in combination with vibration frequency, amplitude, and frequency weighting, on human responses to hand–arm vibration (HAV).Methods: Ten healthy male subjects were exposed to two levels of HAV: 125 Hz–5.0 m/s2 and 125 Hz–20.0 m/s2 (represented as a combination of vibration frequency and rms acceleration) using two different handles (22 and 35 mm in diameter) excited with a shaker. A simplified version of method of limits were used to measure vibrotactile perception thresholds and TTSs were then calculated as the difference between fingertip vibrotactile perception thresholds measured before and after 5 min vibration exposure. Results: At 125 Hz–5.0 m/s2 vibration, the handle size significantly affected TTSs in fingertip vibrotactile perception. In contrast, the handle size did not significantly affect the TTSs at 125 Hz–2.0 m/s2 vibration. Conclusions: Our results suggest that handle size is more sensitive to the TTS in fingertip vibrotactile perception under relatively lower vibration level. From a viewpoint of risk assessment to HAV exposure, TTS after short-term exposure to HAV is indicative of HAV syndrome resulted from long-term exposure to HAV. Since the long-term effect has been the accumulation of repeated short-term effect of HAV, our results suggest that the tool handle size is recommended to be designed based on the vibration level so as to diminish TTS."

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