Effects of frequency content from exposures with the same A-weighted equivalent level

According to traditional measurement methods, signals with the same A-weighted equivalent level should pose the same hazard to the auditory system. As a measure of hazard, it was assumed that Temporary Thresholds Shifts (TTS) reflect the onset of alterations to the hearing system that, if continued, will eventually lead to a permanent damage. Under this premise, results form a TTS experiment using three different band-passed signals taken from one channel of a binaural recording of an industrial mill are discussed [1]. The main result from this experiment is that there is a considerable difference in the resulting TTS after exposures presented at the same A-weighted equivalent level and vary only in frequency content.