[Analysis of hearing protector fit-test results and factors influencing the effect of intensive training among noise-exposed workers]

Objective: To evaluate the noise reduction effect of hearing protectors and to investigate factors influencing the effect of intensive training among noise-exposed workers. Methods: A self-controlled before-and-after intervention study was conducted from March to June 2024. A total of 273 noise-exposed workers were randomly recruited from three machinery manufacturing enterprises in Tianjin. The personal attenuation rating (PAR) was measured using a hearing protector fit-testing system. Workers who failed to meet the standard received one-on-one intensive training and repeated tests. Between-group comparisons of baseline PAR values were performed using the Mann-Whitney U test or Kruskal-Wallis H test. Comparisons before and after intervention were conducted via the Wilcoxon signed-rank test and McNemar's paired chi-square test. Generalized linear models (Poisson distribution with log link function) were applied to analyze factors affecting intervention efficacy (post-intervention PAR minus pre-intervention PAR) . Results: Among the 273 workers, the baseline pass rate of PAR was 49.45% (135/273). Statistically significant differences in baseline PAR were observed among workers with different genders, years of service, noise exposure levels, and daily noise exposure durations (all P<0.05). For the 138 workers who failed the baseline test, the median PAR increased from 5 dB to 17 dB (Z=-9.82, P<0.001), and the pass rate increased to 92.31% (252/273). After adjusting for baseline PAR, male workers achieved better intervention effects than female workers (β=0.37, 95%CI: 0.13-0.61, P=0.003). Workers with a working seniority of≥26 years exhibited a poorer intervention effect compared with those with seniority ≤6 years (β=-0.71, 95%CI: -1.12~-0.30, P=0.001). Noise exposure level was negatively correlated with intervention outcomes (β=-0.03, 95%CI: -0.05~-0.02, P<0.001) . Conclusion: Hearing protector fit testing combined with one-on-one intensive training can significantly improve workers' Personal Attenuation Ratings (PAR). Female workers, those with longer service years, and those exposed to high noise levels show relatively smaller improvement and should be prioritized as key populations for targeted intervention.