[Annoyance and loudness measurements in auditory fatigue and recovery under different sound exposures].

In the course of two experimental studies the individual evaluations of noise annoyance during sound exposure were compared with the experimental auditory fatigue (TTS) and the recovery functions. In both studies, in fourteen young men with normal hearing capacity, a temporary threshold shift was built up and then the subjects were submitted during the recovery period to different second-noise levels (narrow band noise and white noise). The loudness estimations and the evaluations of noise annoyance were scaled at the same points as TTS was measured. The poststimulatory recovery of hearing was significantly delayed, even at noise levels of 65 and 75 db. The evaluations of loudness and noise annoyance corresponded well with the recovery of hearing. In the first experiment, the mean values of noise annoyance ratings increased after 16 min of the second noise exposure, in spite of a further decrement of auditory fatigue. In the second experiment, the mean values of noise annoyance ratings remained almost unchanged during the secondary noise exposure. Regarding individual evaluations, however, the noise annoyance ratings of half of the subjects increased whereas the other half decreased. These results are interpreted as a habituation respectively a sensitization process.