Biological Development and the Normal Voice in Puberty

The pubertal voice in musically trained (voice conscious) boys and girls was investigated with voice range profiles and fundamental frequency (F0) in running speech during reading of a standard text. The methods were based on: 1) development and evaluation of the function of phonetograph 8301 made by the firm Voice Profile, 2) combined electroglottographic and stroboscopic examination of the movements of the vocal folds in speech. The voice analysis was compared with measurements of: 1) pubertal stages in youngsters and 2) hormonal analysis of all androgens and in girls also estrogens. The voice range profile measured total pitch and loudness range and an area calculation was made of measured semitones x dB(A). An evaluation was made of the electroglottographic curve, combining it with a marking of the stroboscopic phases of the vocal folds on the curve with a photocell. The electroglottographic single cycles were stable and 2000 consecutive electroglottographic cycles were measured in 48 boys and 47 girls, aged 8-19 years, in order to measure fundamental frequency in a reading situation. Individual and average voice range profiles for sopranos, altos, tenors and bassos were examined. The yearly change of voice range profiles showed a correlation to total serum testosterone of r = 0.72 in the boys, and serum estrone of r = 0.47 in the girls. The change in fundamental frequency in puberty was analyzed in 48 boys. Single observations of the fundamental frequencies showed that total serum testosterone over 10 nmol/l serum probably represented values for a boy with a pubertal voice. The voice parameters were analyzed in 47 girls. However, hormonal analysis and pubertal examination was only possible in 41 girls. F0 was only related to estrone r = -0.34 (p < 0.05). The increase of estrone and of fundamental frequency range (F0 range) had a predictive value (p < 0.05) for the fall of F0 from 256 to 241 Hz in puberty.