Relative Duration of Quiet Periods Between Events Influences Noise Annoyance: a Laboratory Experiment with Helicopter Sounds
* Presenting author
Besides the commonly considered time-averaged noise exposure metrics such as the Lden, additional indicators (e.g., maximum level, eventfulness, or relative quiet time) might improve the prediction of noise annoyance. An experiment was carried out on the effects of relative duration of quiet periods on annoyance reactions to helicopter noise scenarios, with the relative duration being the ratio of total duration of quiet periods in a sound scenario to its total duration. Recorded flybys were spatially reproduced with a hemispherical loudspeaker array in the laboratory. Ninety-second noise scenarios were prepared, containing two, three, four, or five flybys. All scenarios exhibited the same Leq of 66.5 dB(A), however, differed in the number of flight events and the exposure levels of individual flybys. Subjects were asked to make paired comparisons (i.e., two-alternative forced choices) for three pairs of scenarios. In each pair, one scenario had a larger number of flybys than the other; i.e., 4 vs. 2, 5 vs. 2, or 5 vs. 3. An analysis of the data of 56 subjects was carried out to investigate the effect of the relative duration of quiet periods between events on annoyance. The results indicate that longer quiet periods may mitigate noise annoyance.