Adult listeners are capable of identifying the gender of speakers as young as 4 years old from their voice. In the absence of a clear anatomical dimorphism in the dimensions of pre-pubertal boys' and girls' vocal apparatus, the observed gender differences may reflect children's regulation of their vocal behaviour. A detailed acoustic analysis was conducted of the utterances of 34 6-to 9-year-old children, in their normal voices and also when asked explicitly to speak like a boy or a girl. Results showed statistically significant shifts in fundamental and formant frequency values towards those expected from the sex dimorphism in adult voices. Directions for future research on the role of vocal behaviours in pre-pubertal children's expression of gender are considered.Introducing a recent special issue on gender and relationships, Leman and Tenenbaum (2011, p. 153) draw attention to 'the ways in which children practise future gender roles in everyday interactions with their peers and parents'. Indeed, children are known to exhibit gender-typed patterns of behaviour from a young age. Boys and girls prefer gender-normative toys (Martin, Eisenbud, & Rose, 1995) and play styles (Hay et al., 2011;Munroe & Romney, 2006) and are more likely to choose same-sex peers as playmates (Golombok et al., 2008;Zosuls et al., 2011). We also know that young children are capable of regulating their behaviour in gender-typed ways -what we might call 'self-presentation of gender' -under given social circumstances, such as the presence of a same-sex peer group (Banerjee & Lintern, 2001). With regard to verbal behaviour, much attention has been paid to the content, style, language use, and social dynamics of boys' and girls' conversations (e.g., Leaper & Smith, 2004;Leman, Ahmed, & Ozarow, 2005). Yet, surprisingly, one of the most obvious aspects of gender difference in verbal interactions -the voice itself -has been largely ignored.Adults can identify the gender of speakers as young as 4 years of age by listening to their voice only (Perry, Ohde, & Ashmead, 2001). In post-pubertal speakers, sex differences in the dimensions of the vocal apparatus give males a lower fundamental frequency (pitch) and lower vocal tract resonances (or formants). Before puberty, boys also speak with lower vocal tract resonances than girls (but with the same pitch: Perry et al., 2001). However, these acoustic differences are not supported by a corresponding anatomical sex dimorphism, suggesting that they have a strong behavioural dimension: children seem to adjust the length of their vocal tract to produce formant frequencies characteristic of their gender. See Appendix S1 for details on sex dimorphism in the human voice.The hypothesis that children control this aspect of their vocal behaviour is plausible in the light of empirical research showing that children from a young age make use of the voice, along with other cues such as faces, in discriminating males and females (see Ruble, Martin, & Berenbaum, 2006). The expression of voice gender is therefore a v...
