Effects of a traffic noise background on judgments of aircraft noise

Abstract

Subjects were asked to rate their annoyance to recorded aircraft noises when combined with several levels of road traffic noise in two sets of numerical category scaling tests. The aircraft and traffic noise levels were typical of a closed-window indoor environment. For one set of tests, the mean background noise level was continuous, whereas for the other set of tests the mean background noise level was changed between each aircraft noise. Under the continuous background noise conditions, the rated annoyance was found to decrease consistently with increasing background noise level. For example, when the aircraft and traffic noise levels were of equal Intensity, the reduction in annoyance was the equivalent of a 5-dB reduction in aircraft noise. For the discontinuous background tests, no consistent change was noted. Regression analyses of the subjective annoyance ratings showed high correlation with the incremental noise pollution level, LNP, developed by D. W. Robinson [NPL Acre Report AC49 (1971)].