Development of aerodynamic aspects in children's voice.

To determine the changes with increasing age in children this study measured the air flow and the acoustic signal in children aged 4-15 years. The subglottal pressure was estimated from the intraoral pressure during the phonation of the word 'ipipi'. From these parameters the glottal resistance and the glottal efficiency were calculated. Since these parameters depend on the sound pressure level, a linear regression of the parameters versus the sound pressure level was done, and the values for 75 dB SPL were taken for statistical analysis. The study found a subglottal pressure in younger children between 6 and 10 cm water column, which seemed to diminish with age. The phonatory flow rate was between 50 and 150 ml/s in younger children, which seemed to increase with age. The glottal resistance did not depend on age, values of 20-250 Ns/m5 at a sound pressure level of 75 dB exceed those for adults given in the literature. The measurements for the glottal efficiency showed a broad variability between 20 ppm and 400 ppm.