Assessment of Tongue Position and Laryngeal Height in Two Professional Voice Populations

Purpose: The purpose of this study was to advance our current knowledge of singer physiology by using ultrasonography in combination with acoustic measures to compare physiological differences between musical theater and opera singers under controlled phonation conditions. Furthering our understanding of singing physiology is important for determining proper technique for training specific singing styles, and for guidance in the prevention and treatment of voice injury. The primary objectives addressed in this study were: 1) To determine if differences in hyolaryngeal and vocal fold contact dynamics occur between two professional voice populations (musical theater and opera) during singing tasks, and 2) To determine if differences occur between musical theater and opera singers in oral configuration and associated acoustic resonance during singing tasks. Method: Twenty-one singers (10 musical theater; 11 opera) were included in this study. All participants were currently enrolled in a music program for at least two semesters. Experimental procedures consisted of sustained phonation on the vowels /i/ and /ɑ/ during both a low-pitch and high-pitch tasks. Measures of hyolaryngeal elevation, tongue height, and tongue advancement were assessed using ultrasonography. Vocal fold contact dynamics were measured using electroglottography. Simultaneous acoustic recordings were obtained during all ultrasonography procedures for analysis of the first two formant frequencies. Results: Significant oral configuration differences, as reflected by measures of tongue height and tongue advancement, were seen between the singing groups. Measures of acoustic resonance also showed significant differences between singing groups during specific tasks. Hyoid elevation was not statistically different between groups, however a trend towards higher hyoid positioning during selected tasks was observed for the musical theater group relative to the opera group. Vocal-fold contact dynamics were not different between groups, though musical theater singers did display slightly higher contact quotient values compared to the opera singers. Conclusions: These findings suggest that musical theater singers alter their laryngeal and lingual structures differently than opera singers under certain controlled conditions. Because singers are at such a high risk of developing a voice disorder, understanding how these two groups of singers manipulate their laryngeal physiology may improve identification of negative vocal behaviors and serve as a preventative step in vocal hygiene