[Progression of accident-induced hearing damage]

There are generally accepted opinions on the origin of auditory lesions due to accidents. The views on their possible progression, however, are divergent. One of the reasons is lack of sufficient information. Therefore serial audiological observations of such lesions are required, as are available for workers exposed to noise. In order to exclude the influence of noise on the organ of hearing, only auditory lesions which were strictly unilateral and which lay within a frequency range not susceptible to noise were followed up. The present study investigates the progressive decrease in hearing associated with the type of injury, the pure-tone audiometric pattern and the progress within a given period of time. It is remarkable that our material shows progressive hearing loss only after trauma due to explosion or head injury, and not after blast trauma. Thus it is not acoustic damage to the internal ear, but only mechanical damage which leads to progression. This theory was advanced by Lehnhardt many years ago.