Effect of Hearing and Head Protection on the Localization of Tonal and Broadband Reverse Alarms

Abstract

Objective This study explored the effects of hearing protection devices (HPDs) and head protection on the ability of normal-hearing individuals to localize reverse alarms in background noise. Background Among factors potentially contributing to accidents involving heavy vehicles, reverse alarms can be difficult to localize in space, leading to errors in identifying the source of danger. Previous studies have shown that traditional tonal alarms are more difficult to localize than broadband alarms. In addition, HPDs and safety helmets may further impair localization. Method Standing in the middle of an array of eight loudspeakers, participants with and without HPDs (passive and level-dependent) had to identify the loudspeaker emitting a single cycle of the alarm while performing a task on a tablet computer. Results The broadband alarm was easier to localize than the tonal alarm. Passive HPDs had a significant impact on sound localization (earmuffs generally more so than earplugs), particularly double hearing protection, and level-dependent HPDs did not fully restore sound localization abilities. The safety helmet had a much lesser impact on performance than HPDs. Conclusion Where good sound localization abilities are essential in noisy workplaces, the broadband alarm should be used, double hearing protection should be avoided, and earplug-style passive or level-dependent devices may be a better choice than earmuff-style devices. Construction safety helmets, however, seem to have only a minimal effect on sound localization. Application Results of this study will help stakeholders make decisions that are more informed in promoting safer workplaces.

Situational Awareness: The Effect of Stimulus Type and Hearing Protection on Sound Localization

“…Indeed, while the mean RMSEs were smallest for the front monitors when HPDs were not used, when HPDs were used, the mean RMSEs for the front monitors exceeded the mean RMSEs for the right and left monitors. Previous studies also found better localization with earplugs than earmuffs [4,7,8,34,37].…”

“…Aside from testing additional types of HPDs with different attenuation spectra and levels, testing different types of speech stimuli is also necessary, particularly words and sentences with different durations and spectra. In addition, following Derey et al [37] who showed the effect of the sound category (vocalizations, traffic sounds, or tones) and behavioral relevance (neutral versus fearful sounds with differential effects on behavior) on localization, the effect of the content's relevance and the speaker's familiarity to the listener should also be tested. An additional limitation of the present study is that the attenuation level of HPDs was measured generally, using a free-field microphone, and not individually for each participant; adding the measurement of individual attenuation levels as a predicting factor for localization would be worthwhile.…”

Uso da dupla proteção auditiva na atenuação do ruído ocupacional

“…Esta revisão foi conduzida conforme as recomendações PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) 16 . As análises foram realizadas pelo programa RevMan 5 ®.…”

Towards a Holistic Model Explaining Hearing Protection Device Use among Workers

“…Table 2 presents known incompatibilities between HPD characteristics and those of the two other triad components and which were mainly gathered from a reference book [1] (see chapter 11) but also from the grey literature [66], research papers focusing on specific issues associated with HPD use [67][68][69] and a general survey on HPD use [70]. These incompatibilities can generate discomforts and thus lead to preferences for a given type of HPD, or in the worst case to the non-use of the HPD.…”

“…Earplugs are preferred by individuals favoring discrete hearing protectors and/or concerned with their hairstyle [1] Earmuffs can be difficult to wear in hot environments [1,67,68] Over-attenuating HPDs can block important environmental sounds such as alarm signals, machine sound and colleagues' speech [1] Earmuffs reduce the localization of the noise sources more than earplugs [69] HPD/Work environment Earplug insertion and removal can be time consuming and incompatible with work tasks when many removals are required during the work shift (and thus, earmuff are preferred in this case [1,70]) Earmuffs can interfere with movements when work is carried out in a tight space [1] Compared to earmuffs, earplug efficiency is more dependent on user training, skill and motivation [1] HPD requiring a periodic re-positioning is not adapted to work tasks based on a fast pace of repetitive movements [71] 1.…”