This study aims to identify the noise exposure and verify if the hearing protection used by these workers is adjusted for the exposure to the impact noise during the activities of Basic Shot Instruction in the Brazilian Army produced by Light Automatic Fusils - FAL, caliber 7.62mm. This study can be considered analytical, since it seeks to establish causal relations among the diverse variables involved. It was used the qualitative approach, in the mapping of the working process; and also the quantitative approach in order to analyze the data in relation to this process. It was possible to have a close estimate of the reality on the basis of data collection triangulation, to include: systematic observation, half structured interview and experimental exercise. Based on the analyses, it can be stated these workers are exposed to a noise which ranges from 147.3 to 171 dB. Therefore, it can be concluded that the 3M 1100 hearing protection, which is largely used by military, do not provide noise reduction, since its reducing value corresponds to NRRsf at 12 dB. Thus, there is no effectiveness in hearing protection for the soldiers.