Cognitive after-effects of vibration and noise exposure and the role of subjective noise sensitivity.

This study investigated the effects on attention performance after exposure to noise and whole-body vibration in relation to subjective noise sensitivity. Sixteen high and 16 low sensitivity male students, as determined by the Weinstein Noise Sensitivity Questionnaire, participated in a within-subjects experiment. Noise and vibration stimuli similar to those usually occurring in forestry vehicles were presented either individually, combined or not at all in four separate sessions lasting approximately 44 min. After exposure, participants completed an attention task and made subjective ratings of alertness. No main effect of noise sensitivity was observed in MANOVA, thus the data was pooled with the data from a pilot study using the exact same procedure without using a noise sensitivity inclusion criterion. The combined data revealed performance degradation in the attention task after exposure to vibration, regardless as to whether it was presented alone or in combination with noise. Increased ratings of alertness after vibration exposure and decreased ratings of alertness after noise exposure were also found. Neither synergistic nor antagonistic effects were observed from the combined noise and vibration exposure.