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Published on: February 10, 2023
Effectiveness of Workplace Noise-risk Classification with Hearing Protection in Preventing Occupational Hearing Loss
1Emergency Office, Hunan Prevention and Treatment Institute for Occupational Diseases (Affiliated Prevention and Treatment Institute for Occupational Diseases of University of South China), Changsha, Hunan, PR China.
Objective:
This study aimed to evaluate the effectiveness of combining workplace noise-risk classification with a hearing protection program to prevent occupational noise-induced hearing loss (ONIHL).
Methods:
This retrospective cohort study included 400 male noise‑exposed workers from an automotive manufacturing company. Based on workshop‑level protection strategies implemented by the company, participants were assigned to either a control group ( n = 200, traditional measures) or an observation group ( n = 200, risk classification plus standardized hearing protection). Outcomes assessed at the end of 2023 included proper personal protective equipment use, average noise exposure, speech-/high‑frequency hearing loss, high‑frequency standard threshold shift (STS), and ONIHL incidence. Statistical comparisons were performed using independent t tests, χ 2 tests, and logistic regression.
Results:
Baseline characteristics were comparable between the groups ( P > 0.05). At follow‑up, the observation group showed significantly better outcomes (all P < 0.05): higher personal protective equipment compliance (87.50% versus 63.00%), lower noise exposure (86.26 ± 1.99 versus 88.72 ± 1.77 dB(A)), and lower rates of speech‑frequency hearing loss (20.00% versus 52.50%), high‑frequency hearing loss (35.00% versus 65.00%), high‑frequency STS (5.00% versus 20.00%), and ONIHL (1.00% versus 5.50%). Job-type subgroup analyses indicated a significant protective effect in stamping (STS: 3.85% versus 15.00%, P = 0.017), but not in welding (4.48% versus 13.85%, P = 0.061); machining showed a significant reduction (3.64% versus 14.55%, P = 0.047).
Conclusion:
The integrated strategy was associated with improved protection compliance, reduced noise exposure, and lower hearing loss rates. However, due to the non‑randomized, workshop‑level assignment, causal inferences should be made cautiously. Prospective studies are needed to confirm causality.
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