Exposure to Peak Sound Pressure Levels in Military Fieldfire Ranges

Abstract

The most prevalent health problem among military personnel is noise-induced hearing loss due to impulse noise from gunfire and blasts or high noise levels from different types of military vehicles used by the Land, Naval and Air Forces. The current study aims to assess the noise levels military personnel are exposed to while conducting peacetime exercises with different types of weapons: automatic rifles, anti-aircraft guns, large calibre artillery systems and training ammunition. The peak sound pressure levels were measured with a Brüel & Kjaer Type 2260 noise analyser and instructors’ noise exposure was monitored using a noise dosimeter Casella CEL-350. Based on the measurements, safe distances from the noise sources with and without hearing protection were calculated. According to national legislation, the occupational peak sound pressure of the noise, should not exceed 137 dB(C). For the most presently studied guns, the sound levels were above 140 dB(C), thus exceeding the limit level value without hearing protection. For heavy machine guns and anti-aircraft cannons, the peak sound levels from a distance of 10 m were 147.5 dB(C) for the Browning (12.7 mm) and 148.6 dB(C) for the ZU-23-2 (23 mm). The safe distance for a person who is not wearing any ear protection is 100 m in case of the Browning and ~ 150 m in case of the ZU-23-2. When firing in a fieldfire range with large calibre artillery systems, the estimated short-term peak sound pressure amounts to 162.0 dB(C). The training ammunition PIL10T shows a maximum calculated peak noise level of 166.6 dB(C) at 2.5 m while the training grenade CN69 produces 132.7 dB(C) at 2.5 m. In the military fieldfire ranges, the peak noise pressure levels exceed the limit level value, except for the “eco-friendly” training grenade CN69. To fulfil the requirement (≤137 dB(C)), the noise generated by large-calibre artillery systems can be attenuated in the outer ear using foam earplugs and earmuffs at the same time, preferably with a Single Number Rating (SNR) of 36 + dB. While exercising with anti-aircraft guns, military personnel and observers without hearing protection should keep a safe distance (This study was financed by the Estonian Ministry of Defence project “Assessment and management of health risks among military personnel”. Any opinions or recommendations expressed in this article are those of the authors and do not necessarily represent the view of the Estonian Defence Forces.).KeywordsWeaponsPeak noise valueHearing protection