Influence of sound source recognition on annoyance judgment

Research on annoyance usually focuses on the annoyance estimation of the perceived acoustic signal. It disregards the fact that the basic aim of the auditory system is the detection of the properties of the sound source and not the sound signal itself. In this study the annoyance caused by a tram and a bus and two pairs of artificially modified original recordings has been investigated under two experimental conditions. In the first, subjects judged the noise annoyance of the original signals (the tram and bus) together with two modified sound sources (a tram-like bus and a bus-like tram). In the second, the original signals were judged together with another pair of modified sound sources (a tram-like noise and a bus-like noise). The tram-like bus and bus-like tram signals were created in the way that hybrid instruments are built, while the tram-like noise and bus-like noise were simply white noise shaped in accordance with the power spectrum envelope of the original signals. Although both types of modified signals had the same power spectra and time patterns as the original signals, the tram-like bus and bus-like tram signals were more similar in their effect on annoyance judgments to the original recordings than the tram-like noise and bus-like noise signals. It is shown that the same acoustic characteristics of signals, including the calculated loudness, does not necessarily entail the same annoyance judgments. The annoyance judgments of two original signals – the tram and bus – obtained in the two psychoacoustic experiments were not the same. A possible explanation of this phenomenon is discussed.