Noise: A Limiting Factor for the Use of Modern Weapon Systems?

Modern weapon systems produce very high levels of impulse and/or continuous noise. Exposure to intense noise induces mechanical and/or metabolic damage to the inner ear. At the hearing threshold the amplitude of the displacements of the sensory structures of the inner ear (stereocilia) is about 10 m (1/100 the diameter of the hydrogen atom). At 120 dB this amplitude reaches 1 micrometer (corresponding to an angular deflexion of ∼ 15 degrees of the stereocilia). Depending on the level of the noise, these structures may break off immediately (i.e., for large continuous and/or impulse noises) or be overpowered by fatigue failure mechanisms (figures 1 and 2).