Leveraging Monaural Exposures to Reveal Early Effects of Noise: Evidence from Police Radio Ear-Piece Use.

The study is observational, so it cannot show that ear-piece use caused tinnitus or temporary symptoms. Exposure levels and durations were estimated from self-reported volume-control settings and usage times, combined with average past measurements of ear-piece output; they were not measured directly for each participant. Ear-piece models differed between forces and roles, and model-specific data were not available. The exposure metric assumes continuous ear-piece sound for 40 hours per week, while actual sound transmission was intermittent, so estimates may be overestimated or underestimated. Hearing outcomes were self-reported, including diagnosed hearing loss, with no record of the test context or professional who identified it. Self-selection may have attracted participants with auditory symptoms, and subjective interpretation could bias reporting of tinnitus, temporary symptoms, and exposure. Ear-piece users were mainly operational personnel and nonusers mainly staff, so job role and other hidden differences may confound the associations. Speech-in-noise testing was done at home on unrecorded consumer audio equipment, and some data were excluded for implausible thresholds. Key between-ear analyses excluded nonunilateral users and people who chose an ear because of hearing pathology in the other ear. These exclusions narrow the sample to consistent unilateral users. Additional bilateral noise from policing and recreational sources may have masked ear-piece effects.

The hearing research was funded by the Medical Research Council and supported by the NIHR Manchester Biomedical Research Centre. The initial Airwave Health Monitoring Study phase, including participant recruitment, was funded by the Home Office. Other funding came from the Medical Research Council and NIHR Health Protection Research Units. The authors declared no potential conflicts of interest.

Do not conclude that ear-pieces cause tinnitus or hearing loss. The study is observational, uses self-reported exposure and symptoms, and ear-piece users differ from nonusers in job role, so other hidden factors may explain the associations.