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अमूर्त

Biological Development and the Normal Voice in Childhood

Mette Pedersen, Anne B Alexius Agersted and Bilal Hussain Akram

The voice in musically trained boys and girls was investigated with phonetograms and fundamental frequency in running speech during reading of a standard text (F0). The methods were based on

• Phonetography of voice profiles

• Combined electroglottographic and stroboscopic examination of the movements of the vocal folds in speech.

The voice analysis was compared with measurements of

• Pubertal stages in youngsters

• Hormonal analysis of all androgens and in girls also estrogens

The phonetograms measured the total pitch and loudness range as well as an area calculation in measured semitones × 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 phonetograms for sopranos, altos, tenors and bassos were examined. The yearly change of phonetograms 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 (F0) 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.