The importance of recording and playback technique for assessment of annoyance

The study presented here is part of a project with an overall aim to evaluate how different sound properties relate to annoyance. In order to achieve this it is necessary to study methodological aspects of importance for the experimentally evaluated annoyance. In previous studies of perception and response to sounds, several methods have been adopted both with regard to recording techniques (monophonic or binaural recordings), playback techniques (through headphones or loudspeakers) and subjective evaluation techniques. The present study was carried out to investigate if there is a difference in perception related to annoyance, loudness and unpleasantness between monophonic recordings played back through a loudspeaker and binaural recordings played back via headphones and to evaluate whether a possible difference depends on temporal and frequency characteristics as well as spatial characteristics of the sound. The experiment also investigates various psychometric methods for achieving responses from subjects, and different durations of the exposure were used. Fifty-four young students participated and three types of stimuli were used in the experiments: road traffic sound, everyday “restaurant” sounds (from using cutlery at platters, moving chairs, talking etc.) and a low-frequency ventilation sound. The stimuli were recorded with two different techniques (monophonic and binaural) and each stimulus was played back at three different sound levels. The monophonic recordings were presented through a loudspeaker and the binaural recordings were presented through both closed (circum-aural) and completely open (free of the ear) headphones. The results show that for all judgments (annoyance, loudness and unpleasantness), there was no significant main effect of recording and playback techniques; however significant interactions between techniques and sounds were found