Experimental exposure to impulse noise in the especially pathogenic impact frequency range.

The pathogenicity of impulse-induced noise depends not only on its intensity, but also on the repetition rate of the individual sound impacts. The reason is the effect exercised by the acoustical reflex. Its protective function is said by some experts to last for only little more than 2 seconds. For this reason, two groups of young persons were exposed to noise impacts whose repetition rates were 2 and 3 seconds, thus falling within the period of time in question. The resulting auditory fatigue (TTS) is analysed. The results of the measurements suggest that the activity of the acoustical reflex lasts less than 2 seconds under these test conditions.