Individual differences in cortisol stress response predict increases in voice pitch during exam stress

Abstract

Despite a long history of empirical research, the potential vocal markers of stress remain unclear. Previous studies examining speech under stress most consistently report an increase in voice pitch (the acoustic correlate of fundamental frequency, F0), however numerous studies have failed to replicate this finding. In the present study we tested the prediction that these inconsistencies are tied to variation in the severity of the stress response, wherein voice changes may be observed predominantly among individuals who show a cortisol stress response (i.e., an increase in free cortisol levels) above a critical threshold. Voice recordings and saliva samples were collected from university psychology students at baseline and immediately prior to an oral examination. Voice recordings included both read and spontaneous speech, from which we measured mean, minimum, maximum, and the standard deviation in F0. We observed an increase in mean and minimum F0 under stress in both read and spontaneous speech, whereas maximum F0 and its standard deviation showed no systematic changes under stress. Our results confirmed that free cortisol levels increased by an average of 74% (ranging from 0-270%) under stress. Critically, increases in cortisol concentrations significantly predicted increases in mean F0 under stress for both speech types, but did not predict variation in F0 at baseline. On average, stress-induced increases in voice pitch occurred only when free cortisol levels more than doubled their baseline concentrations. Our results suggest that researchers examining speech under stress should control for individual differences in the magnitude of the stress response.Keywords: speech under stress; fundamental frequency; cortisol; psychological stress; exam stress 3 Highlights• The finding that voice pitch increases under stress is often not replicated• We tested whether this is tied to variation in the severity of the stress response• Voice recordings and saliva were collected at baseline and during exam stress• Increases in cortisol levels predicted voice pitch under stress but not at baseline• Researchers examining speech under stress should control for the stress response

Tennis grunts communicate acoustic cues to sex and contest outcome

“…This is consistent with observations that F0 increases in response to stressors in both humans and nonhuman mammals (e.g. Briefer, 2012;Pisanski, Nowak, et al, 2016;Wittels, Johannes, Enne, Kirsch, & Gunga, 2002). Men's testosterone levels, which correlate negatively with F0 (Cartei et al, 2014;Dabbs Jr. & Mallinger, 1999), are also higher in winners than losers of competitive encounters (Booth, Shelley, Mazur, Tharp, & Kittok, 1989;Campbell, Orourke, & Rabow, 1988;Elias, 1981;Mazur & Lamb, 1980), and dynamic F0 shifts depend on perceived dominance in dyadic competitive scenarios (Puts, Gaulin, & Verdolini, 2006).…”

“…Players are also likely to experience greater physiological arousal and stress in later stages of matches as, being more proximal to the outcome of the match, individual points become more important in determining the winner. As F0 positively correlates with arousal and stress (Briefer, 2012;Pisanski, Nowak, et al, 2016), including psychological stress elicited during short-term physical tasks (Wittels, Johannes, Enne, Kirsch, & Gunga, 2002), this may contribute to the rise in F0 with match progress.…”

“…As vocalisations produced in a competitive context, tennis grunts may be affected by changes in players' physiological and psychological state (e.g. arousal and stress, which correlate positively with F0, Briefer, 2012;Pisanski, Nowak, & Sorokowski, 2016). Thus, we predicted that grunt F0 would correlate with the outcome of competitive contests (i.e., tennis matches).…”

“…This final prediction stems from the aforementioned negative relationship between F0 and dominance, and evidence that F0 increases under stress, distress, and arousal in both humans (Pisanski, Nowak, et al, 2016) and nonhuman mammals (Briefer, 2012 for review). Finally, we predicted that F0 cues in tennis grunts would influence listeners' attributions of vocalizer sex and match outcome.…”

Voice of Authority: Professionals Lower Their Vocal Frequencies When Giving Expert Advice

“…Other research has sought to identify the patterns and natural sequences of voice modulations occurring when people interact. For instance, nonverbal vocal parameters can change within the same individual across the span of a single conversation or interview (Gregory et al 1993), during oral examinations (Pisanski et al 2016d), when lying (Ekman et al 1976), or depending on the conversational partner (e.g., infant-directed speech: Wang et al 2019). It is not entirely clear how much of these vocal changes are a consequence of emotional arousal, or a result of conscious voice modulation.…”