To examine the basis of emotional changes to the voice, physiological and electroglottal measures were combined with acoustic speech analysis of 30 men performing a computer task in which they lost or gained points under two levels of difficulty. Predictions of the main effects of difficulty and reward on the voice were not borne out by the data. Instead, vocal changes depended largely on interactions between gain versus loss and difficulty. The rate at which the vocal folds open and close (fundamental frequency; f 0 ) was higher for loss than for gain when difficulty was high, but not when difficulty was low. Electroglottal measures revealed that f 0 changes corresponded to shorter glottal open times for the loss conditions. Longer closed and shorter open phases were consistent with raised laryngeal tension in difficult loss conditions. Similarly, skin conductance indicated higher sympathetic arousal in loss than gain conditions, particularly when difficulty was high. The results provide evidence of the physiological basis of affective vocal responses, confirming the utility of measuring physiology and voice in the study of emotion.Descriptors: Emotional prosody, Voice, Electroglottography, Physiology, Difficulty, ValenceThe acoustic characteristics of natural, often involuntary markers of emotion in the voice and the physiological mechanisms responsible for such vocal modulation have as yet received little attention from researchers. In contrast to studies of acted emotional speech, the small number of studies on natural or induced emotional speech (e.g., Alpert, Kurtzberg, & Friedhoff, 1963;Bachorowski & Owren, 1995;Simonov & Frolov, 1973) have failed to identify acoustic patterns specific to different emotions. Instead, most acoustic changes measured in real or induced emotional speech can most parsimoniously be explained in terms of the general physiological arousal characteristic of different emotions. This contrasts with the theoretical view (e.g., Scherer, 1986) that emotions affect the acoustic characteristics of speech along multiple dimensions in a manner similar to the pattern of physiological changes that accompany emotion (e.g., Bradley, Codispoti, Cuthbert, & Lang, 2001;Cacioppo, Klein, Bernston, & Hatfield, 1993).The reasons for the paucity of research on real or elicited emotional speech have been described elsewhere (e.g., Johnstone, van Reekum, & Scherer, 2001;Scherer, Johnstone, & Klasmeyer, 2003). These include the practical difficulty of inducing emotions in the laboratory and the fact that whatever emotional information is carried in speech is often shrouded or masked by other aspects (e.g., linguistic, social, cultural) of the speech signal, as well as the relatively recent development of affordable and effective speech analysis software and hardware. One of the major impediments has been the difficulty of obtaining high-quality, controlled sound recordings of real emotions. A solution to this has been the use of computer tasks and games to induce emotional responses, or at least ...
