"This Is What a Mechanic Sounds Like": Children's Vocal Control Reveals Implicit Occupational Stereotypes

Effects of testosterone on speech production and perception: Linking hormone levels in males to vocal cues and female voice attractiveness ratings

This study sets out to investigate the potential effect of males' testosterone level on speech production and speech perception. Regarding speech production, we investigate intra- and inter-individual variation in mean fundamental frequency (fo) and formant frequencies and highlight the potential interacting effect of another hormone, i.e. cortisol. In addition, we investigate the influence of different speech materials on the relationship between testosterone and speech production. Regarding speech perception, we investigate the potential effect of individual differences in males' testosterone level on ratings of attractiveness of female voices. In the production study, data is gathered from 30 healthy adult males ranging from 19 to 27 years (mean age: 22.4, SD: 2.2) who recorded their voices and provided saliva samples at 9 am, 12 noon and 3 pm on a single day. Speech material consists of sustained vowels, counting, read speech and a free description of pictures. Biological measures comprise speakers' height, grip strength, and hormone levels (testosterone and cortisol). In the perception study, participants were asked to rate the attractiveness of female voice stimuli (sentence stimulus, same-speaker pairs) that were manipulated in three steps regarding mean fo and formant frequencies. Regarding speech production, our results show that testosterone affected mean fo (but not formants) both within and between speakers. This relationship was weakened in speakers with high cortisol levels and depended on the speech material. Regarding speech perception, we found female stimuli with higher mean fo and formants to be rated as sounding more attractive than stimuli with lower mean fo and formants. Moreover, listeners with low testosterone showed an increased sensitivity to vocal cues of female attractiveness. While our results of the production study support earlier findings of a relationship between testosterone and mean fo in males (which is mediated by cortisol), they also highlight the relevance of the speech material: The effect of testosterone was strongest in sustained vowels, potentially due to a strengthened effect of hormones on physiologically strongly influenced tasks such as sustained vowels in contrast to more free speech tasks such as a picture description. The perception study is the first to show an effect of males' testosterone level on female attractiveness ratings using voice stimuli.

Gender-Ambiguous Voices and Social Disfluency

Recently, gender-ambiguous (nonbinary) voices have been added to voice assistants to combat gender stereotypes and foster inclusion. However, if people react negatively to such voices, these laudable efforts may be counterproductive. In five preregistered studies (N = 3,684 adult participants) we found that people do react negatively, rating products described by narrators with gender-ambiguous voices less favorably than when they are described by clearly male or female narrators. The voices create a feeling of unease, or social disfluency, that affects evaluations of the products being described. These effects are best explained by low familiarity with voices that sound ambiguous. Thus, initial negative reactions can be overcome with more exposure.

Human talkers change their voices to elicit specific trait percepts

The voice is a variable and dynamic social tool with functional relevance for self-presentation, for example, during a job interview or courtship. Talkers adjust their voices flexibly to their situational or social environment. Here, we investigated how effectively intentional voice modulations can evoke trait impressions in listeners (Experiment 1), whether these trait impressions are recognizable (Experiment 2), and whether they meaningfully influence social interactions (Experiment 3). We recorded 40 healthy adult speakers' whilst speaking neutrally and whilst producing vocal expressions of six social traits (e.g., likeability, confidence). Multivariate ratings of 40 listeners showed that vocal modulations amplified specific trait percepts (Experiments 1 and 2), which could be explained by two principal components relating to perceived affiliation and competence. Moreover, vocal modulations increased the likelihood of listeners choosing the voice to be suitable for corresponding social goals (i.e., a confident rather than likeable voice to negotiate a promotion, Experiment 3). These results indicate that talkers modulate their voice along a common trait space for social navigation. Moreover, beyond reactive voice changes, vocal behaviour can be strategically used by talkers to communicate subtle information about themselves to listeners. These findings advance our understanding of non-verbal vocal behaviour for social communication.

Peer audience effects on children's vocal masculinity and femininity

Existing evidence suggests that children from around the age of 8 years strategically alter their public image in accordance with known values and preferences of peers, through the self-descriptive information they convey. However, an important but neglected aspect of this 'self-presentation' is the medium through which such information is communicated: the voice itself. The present study explored peer audience effects on children's vocal productions. Fifty-six children (26 females, aged 8-10 years) were presented with vignettes where a fictional child, matched to the participant's age and sex, is trying to make friends with a group of same-sex peers with stereotypically masculine or feminine interests (rugby and ballet, respectively). Participants were asked to impersonate the child in that situation and, as the child, to read out loud masculine, feminine and gender-neutral self-descriptive statements to these hypothetical audiences. They also had to decide which of those self-descriptive statements would be most helpful for making friends. In line with previous research, boys and girls preferentially selected masculine or feminine self-descriptive statements depending on the audience interests. Crucially, acoustic analyses of fundamental frequency and formant frequency spacing revealed that children also spontaneously altered their vocal productions: they feminized their voices when speaking to members of the ballet club, while they masculinized their voices when speaking to members of the rugby club. Both sexes also feminized their voices when uttering feminine sentences, compared to when uttering masculine and gender-neutral sentences. Implications for the hitherto neglected role of acoustic qualities of children's vocal behaviour in peer interactions are discussed. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part II)'.

Voice Cues Influence Children’s Assessment of Adults’ Occupational Competence

The adult voice is a strong bio-social marker for masculinity and femininity. In this study we investigated whether children make gender stereotypical judgments about adults’ occupational competence on the basis of their voice. Forty-eight 8- to 10- year olds were asked to rate the competence of adult voices that varied in vocal masculinity (by artificially manipulating voice pitch) and were randomly paired with 9 occupations (3 stereotypically male, 3 female, 3 gender-neutral). In line with gender stereotypes, children rated men as more competent for the male occupations and women as more competent for the female occupations. Moreover, children rated speakers of both sexes with feminine (high-pitched) voices as more competent for the female occupations. Finally, children rated men (but not women) with masculine (low-pitched) voices as more competent for stereotypically male occupations. Our results thus indicate that stereotypical voice-based judgments of occupational competence previously identified in adults are already present in children, and likely to affect how they consider adults and interact with them in their social environment.