Gender-related acoustic features of voices may play a role in perceived aptitude for academic subjects and occupations. In the present study, parents and teachers rated the perceived competence of children with respect to a range of gender-stereotyped academic subjects and future possible occupations. Ratings were based solely on re-synthesized recordings of 8 children (4 girls, 4 boys) saying a single sentence. Resynthesis involved changing format spacing only, either to the mean for each gender in the larger group from which the four speakers had been selected, or to one standard deviation above or below that mean. In Experiment 1, the speakers were rated for perceived competence in academic subjects by 61 parents and 38 teachers. Results showed that lowered or raised voices led to ratings of different levels of competence in traditionally masculine-typed or feminine-typed academic subjects, although the effects were clearer for boy speakers than for girl speakers. In Experiment 2, the speakers were rated for perceived competence in future occupations by 49 parents and 50 teachers. Results showed that perceptions of both boys’ and girls’ aptitude for gender-typed occupations were even more clearly affected in stereotypical ways by the raised or lowered voices. The results have implications for possible interventions with adults to prevent unintentional stereotyping of children, and also point to the value of this method as an implicit measure of parents’ and teachers’ stereotyping of academic subjects and occupations.