The purpose of this study was to investigate acoustic attributes of the voices of preadolescent children as a function of sex and age. Voice samples of the sustained vowel /a/ were obtained from 180 children, 15 males and 15 females at ages five, six, seven, eight, nine, and ten years. Measurement of fundamental frequency was obtained to determine sex‐related differences and age‐related trends. This acoustic analysis revealed that a male/female difference in fundamental frequency emerged by age seven, and that fundamental frequency decreased significantly in male children only, between age five and age ten.