Physiological responses related to pleasant and unpleasant sounds

Sound is a crucial factor in everyday life, since it impacts on people feelings and reactions to circumstances. Therefore, classifying sounds based on experiential, physiological, and behavioral responses becomes a key factor in the understanding of the relationship between sound and emotions. As reported in the literature, since using a single type of analysis results to be only partially reliable, there is an increasing demand of integration among the various kind of analyses. The aim of this study is to integrate both physiological and self-reported outcomes, in order to provide a more accurate information about the emotions induced by pleasant and unpleasant audio stimuli. In particular, several indices were extracted from physiological signals, which were matched with self-reported outcomes. The results of this study show that cardiac response in terms of sympathetic activation is significantly different for the two types of acoustic artefacts. To further support the physiological responses results, statistical analysis of Loudness, Roughness and Sharpness values was performed. The two types of stimuli seemed to be characterized by significantly different levels of Loudness and Roughness, which were found higher for unpleasant stimuli. Therefore, it is possible to conclude that only one type of measure is not always sufficient to characterize the emotional response to sounds and more than one measure is needed as indicator of listener emotions.