Occupational acoustic trauma is a sudden change in hearing as a result of a single exposure to a sudden burst of sound, such as an explosive blast. The diagnosis of noise-induced hearing loss is made clinically by a physician and should include a study of the noise exposure history. It is almost always bilateral.
Audiometric patterns are usually similar bilaterally.
It almost never produces a profound hearing loss. Once the exposure to noise is discontinued, there is no significant further progression of hearing loss as a result of the noise exposure. Previous noise-induced hearing loss does not make the ear more sensitive to future noise exposure. As the hearing threshold increases, the rate of loss decreases. The greatest loss usually occurs at 4000 Hz.