Longitudinal changes in hearing threshold levels of noise-exposed construction workers

Area of Science:

• Occupational Health
• Audiology
• Public Health

Background:

• Noise-induced hearing loss (NIHL) is a significant occupational health concern.
• Understanding the progression of NIHL is crucial for effective prevention strategies.

Purpose of the Study:

• To conduct a longitudinal analysis of audiometric data from noise-exposed workers.
• To investigate the development of NIHL as a function of noise exposure and age, especially within the first decade of exposure.

Main Methods:

• Analysis of pure-tone audiometry data from 17,930 construction workers over a 4-year period.
• Utilized linear mixed models to assess the relationship between hearing change, noise exposure, duration, and age.
• Investigated hearing loss patterns using data from 3,111 workers tested thrice.

Main Results:

• The mean annual hearing deterioration was 0.54 dB/yr, increasing with noise exposure and age.
• An unexpected improvement in hearing threshold levels (HTLs) was observed during the first decade of noise exposure.
• Hearing loss development exhibited a concave pattern over time, consistent with NIHL.

Conclusions:

• Hearing generally deteriorated over the study period.
• Observed improvements in HTLs at follow-up suggest measurement variation rather than actual hearing improvement.
• The study could not definitively assess NIHL development during the first decade due to these initial HTL improvements.