Localization of reverse alarms with personal safety equipment

Several factors can contribute to the occurrence of accidents involving reversing heavy vehicles, despite the mandatory use of reverse alarms in many workplaces.  Among others, reverse alarms can be difficult to localize in space, which may lead to errors in adequately identifying the source of danger. Previous studies have shown that traditional reverse alarms (“beep-beep”) are more difficult to localize in space than broadband alarms (“pschtt-pschtt”). In addition, personal safety equipment such as hearing protection devices and safety helmets, often required in noisy workplaces where reverse alarms are used, may potentially further impair localization.  This study explored the effect of passive hearing protection devices (earplugs, earmuffs and double protection) and use of a safety helmet on the ability of normal-hearing individuals to localize the two types of reverse alarms, in background noise, while performing a task. Consistent with previous findings, the broadband alarm was easier to localize than the tonal alarm.  While passive hearing protection can have a significant impact on sound localization (with a marked degradation in performance with double protection), use of a safety helmet has a more limited effect. Preliminary results from a study using the same methodology with level-dependent (sound restoring) hearing protection devices are also presented.