Physiology of vocal production in the newborn

Vocal folds of newborns are histologically different from children and adults. Reinke’s space is not clearly individualized. As shown by Titze, this structure is absolutely needed for vocal fold vibration [1]. The hypothesis for vocal production in newborn is that the air column generates itself the acoustic turbulences (vortex) from which the sound merges. Some other possible vibrators within the mammalian production system include the vocal tract [2]. Acoustic analysis of excised larynx of 38 weekstime dead human foetus was performed. An acoustic analysis and a phase portrait were calculated on each recorded sample. A newborn cry was also recorded with the same DAT. Anatomical measurements were performed and a virtual model (Gambit) was designed to modelize turbulences with vocal folds in phonatory position (Fluent 6.0). All data were correlated with those obtained by Laser Doppler Velocimetry. The fundamental frequency of the sound produced by a fixed larynx was higher than those produced by fresh sample or newborn. Phase portraits are very different in each sample. High-frequency whirlwinds were modelized upon each vocal fold. Preliminary results suggest that newborn phonation is a vortex effect coupled with a vibration of supraglottic structures.