Annoyance caused by low frequency sounds : Spectral and temporal effects

The objective of the present laboratory studies was to enable refinements of the current rating procedure for low frequency sounds. To increase our insight into a relevant spectral issue, groups of adjacent frequency bands around 40, 50, and 63 Hz were presented at various sound level combinations. It was concluded that an energy-based summation model predicts annoyance better than the level of a dominant single frequency band does. With regard to unsolved temporal issues, the effects of two types of sound level variations were investigated. The results showed that when the time between successive sound events matches situations around busy airports or along busy railways, the annoyance is well predicted by the equivalent sound level. For amplitude modulated (AM) sounds (f_mod = 1 Hz), however, both overall level and AM depth have to be taken into account. Keywords : amplitude modulation, annoyance rating, energy summation, level variation, rating procedure.