BACKGROUND: Conscripts have a risk for an acute acoustic trauma (AAT) due to exposure to large-caliber weapons or explosions despite the much tighter safety precautions than those for rifle-caliber weapons. AIMS: We aimed to investigate the population-based frequency of AATs after exposure to such noise sources during conscript training in the Finnish Defence Forces (FDF), and to evaluate their possible causes. MATERIALS AND METHODS: We collected all registered AAT incidents from the FDF over the available periods 1997-2003 and 2008--2010. RESULTS: The likelihood of having an AAT from heavy weapon or explosion noise was 0.07%, and the most common noise sources were cannons, bazookas and mortars. CONCLUSIONS AND SIGNIFICANCE: There is a constant need to survey, educate and train personnel regarding risks of noise at military exercises to prevent AATs. This study adds to the existing knowledge on the risk of hearing loss resulting from AAT in military settings.