Pediatric high speed digital imaging of vocal fold vibration: a normative pilot study of glottal closure and phase closure characteristics.

Objective: The aim of the study is to characterize normal vibratory patterns of both glottal closure and phase closure in the pediatric population with the use of high speed digital imaging.

Methods: For this prospective study a total of 56 pre-pubertal children, 5-11 years (boys=28, girls=28) and 56 adults, 21-45 years (males=28, females=28) without known voice problems were examined with the use of a new technology of high speed digital imaging. Recordings were captured at 4000 frames per second for duration of 4.094 s at participants' typical phonation. With semi-automated software, montage analysis of glottal cycles was performed. Three trained experienced raters, rated features of glottal configuration and phase closure from glottal cycle montages.

Results: Posterior glottal gap was the predominant glottal closure configuration in children (girls=85%, boys=68%) with normal voice. Other glottal configurations observed were: anterior gap (girls=3.6%, boys=0%), complete closure (girls=7%, boys=10%) and hour glass (girls=0%, boys=11%). Adults with normal voice also demonstrated predominantly higher percentage of posterior glottal gap configuration (females=75% male=54%) compared to the configurations of anterior gap (females=0% male=7%), complete closure (females=2% male=39%), hour glass (females=3.6% male=3.6%). A predominantly open phase (51-70% of the glottal cycle) was observed in 86% girls and 71% boys. Compared to children, adult females showed a predominantly balance phased closure 46%, followed by open phase (39%) and predominantly closed phase (14%). Adult males showed a predominantly closed phase (43%), followed by predominantly open phase (39%), followed by a balanced phase (18%).

Conclusions: This is a first study investigating characteristics of normal vibratory motion in children with high speed digital imaging. Glottal configuration and phase closure for children with normal voices are distinctly different compared to adults. The results suggest that posterior glottal gap and a predominantly open phase of the glottal cycle should be considered as normal glottal configuration in children during modal pitch and loudness. This study provides preliminary information on the vibratory characteristics of children with normal voice. The data presented here may provide the bases for differentiating normal vibratory characteristics from the disordered in the pediatric population.