Speaker
Description
High-level impulse noise from firearms and explosives poses a major risk of hearing injury, particularly for soldiers and police officers during routine training. When source reduction is not feasible, appropriate Hearing Protection Devices (HPDs) are required to limit individual exposure. However, HPDs must provide sufficient attenuation without unnecessarily compromising comfort, communication, and situational awareness. The required attenuation is usually derived from Damage Risk Criteria (DRC), but the DRC implemented in different national standards are not equivalent. Their predictions may differ substantially because they emphasize different signal properties, such as peak level, effective duration, weighted or unweighted sound exposure, waveform statistics, or auditory-model responses.This study compares several DRC under realistic conditions of HPD use. For this purpose, a shooting-noise dataset covering different weapons and indoor/outdoor environments is combined with impulse-noise insertion-loss measurements of active earmuff protectors, including configurations with and without protective glasses and additional headgear. The resulting estimated under-protector exposures and corresponding reference signals are analysed using criteria such as Pfander, A-weighted sound exposure, C-weighted peak level, AHAAH, and other exposure metrics. For each condition, hazard levels and Maximum Permissible Exposures are compared across criteria.The results show that realistic fitting conditions affect not only the transmitted level but also its interpretation by different DRC. In particular, seal leakage introduced by glasses increases under-protector exposure and may change the ranking of HPD configurations as well as the estimated admissible number of shots. Realistic fitting conditions and environmental acoustics should therefore be explicitly considered when deriving operational exposure limits.