Long-term average spectrum (LTAS) analysis of sex- and gender-related differences in children's voices.

Long-term average spectrum (LTAS) analysis offers representative information on voice timbre providing spectral information averaged over time. It is particularly useful when persistent spectral features are under investigation. The aim of this study was to compare perceived sex of children to the LTAS analysis of their audio signals. A total of 320 children, aged between 3 and 12 years, were recorded singing a song. In an earlier analysis, the recorded voices were evaluated with respect to perceived and actual sex by experienced listeners. From this group, a subgroup of 59 children (30 boys and 29 girls) was selected. The mean LTAS revealed a peak at 5 kHz for children perceived with confidence as boys, and a flat spectrum at 5 kHz for children perceived confidently as girls (whether male or female in actuality).