Evaluation of hidden hearing loss in normal-hearing firearm users

Area of Science:

• Audiology
• Neuroscience
• Occupational Health

Background:

• Noise exposure can cause temporary threshold shift (TTS) and cochlear synaptopathy, a form of "hidden hearing loss".
• Firearm use is a significant risk factor for noise-induced hearing deficits.
• Young adults with normal audiometric thresholds may still be at risk for cochlear synaptopathy.

Purpose of the Study:

• To evaluate the risk of noise-induced cochlear synaptopathy in firearm users.
• To compare cochlear nerve response in firearm users versus non-firearm users with normal hearing.

Main Methods:

• Retrospective study of 70 participants (18-25 years old), including 33 firearm users (EXP) and 37 controls (CNTRL).
• All participants had normal audiometric thresholds (≤20 dB HL from 0.25 to 8 kHz).
• Auditory function assessed using standard and extended high-frequency audiometry, Words-in-Noise, distortion product otoacoustic emissions, middle ear muscle reflex, and auditory brainstem response.

Main Results:

• No statistically significant differences in auditory performance were found between EXP and CNTRL groups.
• Importantly, 91% of firearm users reported consistent hearing protection use.
• This suggests hearing protection effectively preserves cochlear and neural auditory function.

Conclusions:

• Consistent use of hearing protection during firearm use prevents noise-induced cochlear synaptopathy.
• Inconsistent or incorrect hearing protection use may lead to cochlear injury.
• Selective neural injury is less likely in the absence of cochlear injury among firearm users.