Combined exposures of noise and whole-body vibration and the effects on psychological responses, a review

The aim of this review is to shed light on a research area that concerns the studies of psychological responses to combined exposures of noise and whole-body vibration (WBV). Vehicle drivers are a group of workers that are often exposed to multiple stressors like noise, WBV and mental loads. Degraded performance because of environmental stressors may lead to injury or accidents. Standards that govern health risk assessment do not take into consideration the complexities of these multiple exposure environments (ISO 1997a, ISO 1999). Some studies have shown that the effect of one factor may be different than the effect of two factors presented together. For example, negative combined effects have been found in tracking tasks (Sommer and Harris, 1973), in arithmetic tasks (Harris and Schoenberger, 1980), as well as in subjective ratings (Ljungberg, Neely, Lundstrom, 2004), although in many of the studies the noise and WBV stimuli have been very unlike those that can be found in real workmg environments. Applying methods from the "irrelevant sound" paradigm (e.g Jones, 1990) by using short-term memory tasks with a serial component as well as focus on frequencies rather than level has been revealed to tap the resources both objectively and subjectively more in both noise and WBV studies (e.g. Banbury et al. 2001; Kjellberg, 1990) Still, most experiments that have been conducted have focused on rather short exposure times in controlled laboratory settings. Using longer exposure times might also reveal other results since longer exposure times may be negatively related to sensitivity to noise and WBV (Abbate et al. 2004; Neely, Lundstrom, and Bjorkvist, 2002, Weinstein, 1978)