Computerized tomography measures during and after artificial lengthening of the vocal tract in subjects with voice disorders

Abstract

Purpose.The present study aimed to observe the effect of two types of tubes on vocal tract bidimensionaland tridimensional images.Methods.Ten participants with hyperfunctional dysphonia were included. Computerized tomography was per-formed during production of sustained [a:], followed by sustained phonation into a drinking straw, and then repetitionof sustained [a:]. A similar procedure was performed with a stirring straw after 15 minutes of vocal rest. Anatomicdistances and area measures were obtained from computerized tomography midsagittal and transversal images. Vocaltract total volume was also calculated.Results.During tube phonation, increases were measured in the vertical length of the vocal tract, oropharyngeal area,hypopharyngeal area, outlet of the epilaryngeal tube, and inlet to the lower pharynx. Also, the larynx was lower, andmore closure was noted between the velum and the nasal passage.Conclusion.Tube phonation causes an increased total vocal tract volume, mostly because of the increased cross-sectional areas in the pharyngeal region. This change is more prominent when the tube offers more airflow resistance(stirring straw) compared with less airflow resistance (drinking straw). Based on our data and previous studies, it seemsthat vocal tract changes are not dependent on the voice condition (vocally trained, untrained, or disordered voices),but on the exercise itself and the type of instructions given to subjects. Tube phonation is a good option to reach ther-apeutic goals (eg, wide pharynx and low larynx) without giving biomechanical instructions, but only asking patientsto feel easy voice and vibratory sensations.