Vowel-Specific Tongue Adjustments in the Register Transition of Female Operatic Singers

Objective: The change in register from head to chest voice has been widely associated with laryngeal adjustments, including greater vocal fold adduction, longer glottal closed phase, and vocal fold thickening [Henrich, D. N. (2006) LPV 31]. Vocal tract length has been shown to have an effect on the transition [Tokuda et al. (2010) JASA 127], and there is evidence for supralaryngeal differences between registers with respect to resonance frequencies [Echternach et al. (2011a) JASA 129]. However, comparatively little research has looked at differences in the position of supralaryngeal articulators. Echternach and colleagues conducted a series of real-time MRI studies investigating the shape of the supraglottal vocal tract between registers, and reported that the tongue dorsum was more elevated in falsetto than in modal voicing for male alto operatic singers [Echternach et al. (2011b) J. Voice 25]. Another study comparing classical singers and yodellers found the tongue dorsum to be more elevated for higher pitches [Echternach et al. (2011c) LPV 36]. These studies showed significant variation across individuals and different vowels [Echternach et al. (2014) J. Voice 28]. However, these studies measured the tongue at only two points: tongue dorsum height and pharynx width. The present study aims to provide a qualitative investigation into the specific tongue adjustments made during register shifts by female operatic singers.

Method: We will report on overall changes in tongue contour using ultrasound imaging of the midsagittal plane. Female opera singers will be recorded singing a chromatic scale through their register transition on six different vowels: /a, e, i, o, u, ɚ/.

Results and Conclusion: Results from a pilot study of one mezzo-soprano and one soprano indicate that tongue adjustments made between the registers are vowel-dependent. For low and mid vowels /a, e, o, ɚ/, the tongue dorsum is more elevated in head voice than in chest voice, while high vowels /i, u/ show little no difference in tongue position between the registers. We will discuss whether the previously identified patterns are observed in results from a larger pool of singers, and implications for voice pedagogy.