2015-03-01 12:00 - Messages

Uni-, bi- and tri-modal warning signals

Effects of temporal parameters and sensory modality on perceived urgency
Multi-sensory warnings can potentially enhance risk communication. Hereto we investigated how temporal signal parameters affect perceived urgency within and across modalities. In an experiment, 78 observers rated the perceived urgency of uni-, bi-, and/or tri-modal stimuli as function of 25 combinations of pulse duration (range 100–1600 ms) and inter pulse interval length (100–1600 ms). The results showed that perceived urgency increases with signal rate. Inter pulse interval showed a larger effect than pulse duration and the largest differences in perceived urgency as function of inter pulse interval occurred at the smallest pulse duration (100 ms). The effects of pulse duration and inter pulse interval were universal across modalities. Bi- and tri-modal signals were perceived as more urgent than each of their uni-modal constituents. We conclude that temporal parameters can be deployed to construct integrated, multi-sensory warning signals with a pre-specified degree of perceived urgency.

Source: van Erp JBF, Toet A, Janssen JB. Safety Sci. 2015; 72: 1-8.
http://dx.doi.org/10.1016/j.ssci.2014.07.022

Relationships of neurosensory disorders and reduced work ability to alternative frequency weightings of hand-transmitted vibration

Objective: This cohort study aims to compare the performance of alternative frequency weightings of hand-transmitted vibration (HTV) for the assessment of the exposure–response relationships for neurosensory disorders and reduced work ability among HTV-exposed workers.
Methods: In a 3-year follow up study, the occurrence of neurosensory symptoms and reduced work ability, and the response to quantitative sensory testing (grip force, manipulative dexterity, touch sensation) were investigated in 249 HTV-exposed workers and 138 healthy controls. Among the HTV-exposed workers, the sensory outcomes were related to measures of daily vibration exposure expressed in terms of 8-hour energy-equivalent frequency-weighted acceleration magnitude [A(8)]. To calculate A(8), the acceleration magnitudes of vibration were weighted by means of four alternative frequency weightings of HTV.
Results: The occurrence of neurosensory symptoms, reduced work ability, and abnormalities of sensory tests was greater among the HTV-exposed workers than the controls. Among the HTV-exposed workers, the deterioration of neurosensory outcomes and the reduction of work ability increased on par with the measures of vibration exposure. Exposure–response models revealed that the four alternative frequency weightings of HTV provided the same predictions for the probability of finger numbness among the exposed workers (observed 36% versus predicted 32%).
Conclusions: The findings of this study revealed significant dose–response relationships between measures of vibration exposure, sensory disorders, and reduced work ability among the HTV-exposed workers. There were no differences in the prediction of finger numbness between measures of vibration exposure calculated with alternative frequency weightings of HTV.

Source: Bovenzi M, Prodi A, Mauro M. Scand J Work Environ Health, 2015.
http://dx.doi.org/10.5271/sjweh.3490

NIOSH Study Spans over Thirty Years of Hearing Loss Trends

A new study from the National Institute for Occupational Safety and Health (NIOSH) examines thirty years of hearing loss trends experienced by workers exposed to noise while on the job, across various industries. The study, published by the American Journal of Industrial Medicine, found that while progress has been made in reducing the risk of hearing loss within most industry sectors, additional efforts are needed within the Mining, Construction, and Healthcare and Social Assistance sectors.

Source: http://www.cdc.gov/niosh/updates/upd-03-04-15.html

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