Affective and physiological responses to environmental noises and music

Abstract

Research suggests that respiratory patterns may reflect general dimensions of emotional response. In this study, we investigated the relationships between judgments of affective valence (pleasantness) and arousal and respiratory responses to acoustic stimuli. Sixteen environmental noises and 16 musical fragments of 30 s duration were presented to 31 participants, while respiration, skin conductance level and heart rate were recorded. Judgments of valence and arousal were registered using the 9-point Self-Assessment Manikin. For noises, breathing accelerated and minute ventilation augmented with decreases in pleasantness for low-arousal stimuli and with increases in arousal for positive stimuli. For music, breathing accelerated and minute ventilation augmented with increases both in rated valence and arousal. Skin conductance level increased with arousal ratings for music but not for noises, whereas mean heart rate increased with rated arousal for noises but not for music. Although both noises and music are sound-vibrations, differences in the relationships between affective judgments and physiological responses were found suggesting differences in the processing of the two types of acoustic stimuli.

Introduction

Emotional reactions can be evoked by stimuli in different sensory modalities. Those associated with processing pictures have been extensively investigated and several studies have provided evidence for a correspondance between physiological variables (skin conductance, heart rate, startle blink reflex, facial EMG, brain activity) and the emotional dimensions of valence and arousal (see Hamm et al., 2003 for review). We recently investigated respiratory responses while viewing affective pictures using the same dimensional framework (Gomez et al., 2004a). Several respiratory measures were found to covary with judgments of valence and arousal. To extend our knowledge of respiratory responses during affective processing, we investigated in this study affective and respiratory reactions while listening to environmental noises and musical passages.

Both noises and music are sound-vibrations. However, one would be hard-pressed to call the crying of a baby, a siren or a ringing telephone ‘music’. Thus, differences must exist between what we normally call noises and what we normally call music. These differences may be associated with different processing of the two types of acoustic stimuli and reflect themselves in different physiological responses. Theories of auditory event perception have highlighted a distinction between ‘everyday’ and ‘musical’ listening (Gaver, 1993). However, this account of listening in two ways has been recently challenged by Dibben (2001).

Only one study has assessed physiological responding (skin conductance, heart rate, startle blink reflex, facial EMG) to a large sample of naturally occurring sounds (Bradley and Lang, 2000). To our knowledge, no study has yet explored the relationships between self-reported affective responses and respiratory reactions to natural noises. A number of studies have investigated affective and physiological responses to music (for review see Bartlett, 1996). In her doctoral thesis, Witvliet (1998) adopted the framework of valence and arousal to assess the effects of music on skin conductance, heart rate, facial EMG, and the startle reflex. Few studies, however, have assessed respiratory responses (Krumhansl, 1997, Nyklı́cek et al., 1997) and none have included a detailed breathing analysis as recommended by respiratory psychophysiologists (Wientjes, 1992, Boiten et al., 1994).

The available evidence concerning the relation between emotions and respiration indicates that more rapid breathing is associated with increases in arousal (e.g. Nyklı́cek et al., 1997, Boiten, 1998, Van Diest et al., 2001). Until now, no clear relationship between respiratory volume and emotional dimensions have been obtained (Boiten, 1998, Gomez et al., 2004a, Gomez et al., 2004b). Mean inspiratory flow and minute ventilation increase with increases in arousal (Boiten et al., 1994, Boiten, 1998, Gomez et al., 2004a) but may also be influenced by the affective valence of the stimuli (Gomez et al., 2004a). Finally, very little is known about the influence of affective stimuli on the relative contribution of the rib cage and the abdomen to respiratory volume (Boiten, 1998).

The main purpose of the present study was to assess the relationships between judgments of affective valence and arousal and physiological responses to noises and to music. To this end, we presented 16 noise sources and 16 musical fragments to 31 participants, each lasting 30 s in duration. We recorded respiration, skin conductance level, heart rate and judgments of valence and arousal. Moreover, we were interested in comparing the two-dimensional distribution of valence and arousal ratings for noises and musical fragments.