Objective: To determine whether a ski helmet reduces skiers' hearing particularly sounds that can warn skiers of potentially dangerous situations.
Design: Randomized repeated measures (first part), environmental field measurements (second part).
Setting: Audiology Centre of Rijeka Medical School, ski slopes at Platak resort.
Participants: Thirty healthy subjects not used to wearing a helmet each served as their own control.
Intervention: Ski cap, ski helmet, and no intervention in randomized order.
Main outcome measurements: Laboratory open-field audiometric testing: bareheaded, ski cap, and ski helmet (0.125-8 kHz protocol), and environmental A-weighted sound measurements on the slope for potentially dangerous situations like snowboarder breaking or skier passing by. In both parts of the study, the sound pressure levels (dB) and sound spectrum frequencies were analyzed.
Results: First part-No differences were found between bare head and wearing only a ski cap. Significant sound attenuation characteristics of the helmet were determined for frequencies 2, 4, and 8 kHz (P < 0.001). Second part-High sound pressure levels were found for all the danger sounds measured on the slope, especially at frequencies that were most affected by helmet sound attenuation (2-8 kHz) in previously conducted laboratory tests.
Conclusions: Helmets could influence the level of the hearing threshold in frequencies between 2 and 8 KHz. The spectrum of danger sounds on the slope has high pressure levels at frequencies that were most affected by helmet sound attenuation characteristics (2-8 kHz), so the helmet wearers might misinterpret the sounds of potentially dangerous situations because the sound might be distorted.