FormalPara Core Messages

How do the high-speed videos change from the prepubertal over the pubertal to the postpubertal period?

  • How do the tonal range, dynamic range, and Voice Range Profile of the voice develop for girls and boys?

  • How does the fundamental frequency of the speaking voice (F0) develop in girls and boys?

  • How does the relationship between the voice parameters and the pediatric stages change in girls and boys?

  • How do the androgen and estrogen hormones relate to childhood development stages of voice change in girls and boys?

Measurements that include high-speed films, Voice Range Profiles, and conversational speech fundamental frequency provide important information which—when interpreted in conjunction with pediatric and hormonal parameters—can expand our understanding of the way in which the development of the voice proceeds.

Considering the information which we have accumulated from our investigations, we can answer the questions which we posed at the start of this work in the following way:

  • How do high-speed videos change during childhood, from the prepubertal over the pubertal to the postpubertal period?

    High-speed videos have some characteristics in childhood around the pubertal period, where irregularity of the margins of the vocal folds can suggest two child and two adult registers. The vocal folds are hardly ever shiny and often thickened, with a rear glottal insufficiency.

  • How do the tonal range, dynamic range, and Voice Range Profile of the voice develop for girls and boys?

    The Voice Range Profile in tones times dB(A) changes gradually for both sexes during childhood. In puberty, they temporarily decrease in the age range around 13.5 and 14.5 years; this phenomenon is more pronounced for boys than for girls. Voice Range Profiles of the various categories (soprano, alto, tenor bass) are not significantly related to pediatric and hormonal development in childhood. The yearly development of average Voice Range Profiles is presented; they are significantly related to estrogens and androgens.

  • How does the fundamental frequency of the speaking voice (F0) develop for boys and girls?

    The speaking voice (F0) changes in both sexes during childhood, especially in puberty. For boys, the change is dependent on the serum testosterone level (and predicted by the fall of the sex hormone-binding globulin (SHBG)), and for girls on the estrone level, predicted by the rise hereof and the enhanced semitone range during speech.

    In the male group, the focus is on the mean fundamental frequency of the speaking voice (mean F0) dropping one octave during a period of around 8 months, while in girls, the focus is mainly on the semitonal range of the speaking voice which expands to five semitones in Hz one octave higher up than boys, which means a double activity of the vocal folds compared to boys. For both sexes, the age parameter was around 13.5 and 14.5 years.

  • How does the relationship between the voice parameters and the pediatric stages change in boys and girls?

    The voice changes take place during stages 2–4 of puberty, during the period when the testosterone level rises in boys related to a fall on the mean F0 of one octave. For girls, the drop in the fundamental frequency of the speaking voice (mean F0) of one-third to one-fourth octave follows the increasing levels of estrone and estrone sulfate and the expanded semitonal range of the speaking voice. The timing of puberty and the way in which it proceeds are different for boys and girls.

  • How do the androgen and estrogen hormones relate to childhood development stages of voice change in girls and boys?

    The voice changes during puberty depend on the testosterone level and the estrone level, respectively, for boys and girls, independently of age. Nevertheless, the changes of voice are hormone dependent in various ways and take for both sexes around 13.5 and 14.5 years. The falling level of SHBG significantly precedes (predicts) the drop in the fundamental frequency of the speaking voice (mean F0) in boys in pediatric stages 2–4. In girls, the increasing semitone range and estrone values precede (predict) the drop in mean F0.

Our results can be the basis for further research, e.g., for the voice also as a biomarker in pathology. Until now, it has not been possible to set up results for girls corresponding to boys. Apart from reasons of tradition, limited knowledge of girls’ voices and the way in which they change during puberty have played a role. To achieve optimal understanding of the development of vocal expression for girls, one should take into consideration that the speaking voice should lie in the biologically determined frequency range that is correct for each individual; this is especially important in pathology [1, 2].