[Limits between normal and pathologic auditory fatigue following acoustic stress with high peak pressures in its...

The extent of hearing fatigue as a consequence of acoustic impacts is an important factor in predicting an anticipated hearing impairment. It is essential to know whether hearing fatigue is due to physiological or pathological conditions. Mass screenings of thousands of soldiers suffering from hearing fatigue due to acoustic impact, showed that hearing fatigue is subject to considerable individual fluctuation. The time of recovery, or rather the time required by the auditory reception to return to the preimpact threshold, is of paramount importance. Recovery from an audiometrically traceable TTS within 10 minutes can be considered unobjectionable. Recovery time of up to half an hour can be found in 10--20% of the screened personnel, depending on the impact. This is within physiological variation range and can be considered unobjectionable. Recovery times of a TTS of up to 3 hours constitute a limit beyond which pathological effects in the cochlea can be expected. Recovery times of 24 hours and more signify a definite impairment if impacts continue.