The Effect of Onset Rate on Aircraft Noise Annoyance. Volume 1. Laboratory Experiments

A laboratory study has been conducted to quantify the effect of onset rate on the annoyance of noise from aircraft operating on low-attitude military training routes (NTR). Using indoor and outdoor listening facilities, recordings of MTR sounds were presented to groups of participants. The recordings included actual sounds, plus sounds which had been modified to have particular onset rates and decay rates. Onset rates ranged from 1.3 to 152 dB/second. Sound exposure level of the stimuti varied from 65 to 95 dB indoors, and 80 to 110 dB outdoors. Participants recorded their annoyance on a nine-point scale. It was found that onset rate5 faster than 30 dB/second caused increased annoyance. The best fit to the data is an onset rate adjustment to SEL, which has the form of a linear relation on a dB versus log(rate) scale, from 0 dB at a rate of 30 dB/second to ii dB at 150 dBjsecond. Below 30 dBjsecond, there is no adjustment, and data were not collected at higher rates. Stimulus duration and decay rate were found to have some effect, but these quantities are sufficiently well correlated with onset rate that a model based on onset rate alone is adequate. It was found that the direction of approach of the aircraft was not a major effect, but there is a substantial difference in annoyance between indoor and outdoor settings.