Objectives In a questionnaire conducted by The Royal Norwegian Navy in 2002/2003, 38% of the personnel reported to be much/very much exposed to noise and 24% reported reduced hearing. Based on these findings, further investigation on the working conditions on board naval vessels and mapping NIHL among the personnel on board was initiated. A part of this study is to compare noise levels and occurrence of hearing loss on large vessels like frigates and smaller vessels like coastal corvettes.

Methods Noise levels in areas were measured on three costal corvettes (CC) and three frigates (F) using Brüel & Kjær Hand-held Analyzer Type 2250. All personnel working on frigates and coastal corvettes were invited to audiometric testing, using Interacoustics AD226. NIHL was classified as ≥ 25 dB in at least one ear at 3000, 4000 or 6000 Hz. They completed a questionnaire concerning noise exposure and background information.

Preliminary Results Noise levels in cabins range from 68.5 dB(A) to 85.5 dB(A) in CC and from 42.1 dB(A) to 80 dB(A) in F. 157 persons were currently or previously working on F and 91 persons were currently or previously working on CC. The prevalence of NIHL among personnel in CC was 40.7% and 28.7% among personnel in F (Pearson Chi-Square test, P = 0.053). Mean age for CC was 32 and for F 28 years. When adjusting for age using logistic regression no differences in NHIL among the two vessel groups were found.

Conclusions The CC has higher measured noise levels than the F. Our analysis shows a higher prevalence of NIHL among personnel currently or previously working on CC compared to F. When adjusting for age the effect disappears. This may indicate that the NIHL found was not related to vessel group.