ABSTRACT
OBJECTIVES: This study aimed to estimate vocal loading in loud phonation of a vowel and two widely used semiocclusion voice exercises (SOVTEs). Impact stress (IS) was estimated from glottal closing speed, inertial forces from the second derivative of glottal opening and closing. STUDY DESIGN: Experimental study in vivo. METHODS: A vocally healthy male sustained the [o:] vowel with habitual loudness and loudly: (1) without a tube, (2) into a silicone "Lax Vox" type tube (35 cm in length, 10 mm in diameter) outer end submerged 10 cm in water, and (3) into a straw (length 12.6 cm, diameter 2.5 mm) the outer end in air. He tried to use equal effort in all loud samples. High-speed video-laryngo-endoscopy was performed with a rigid scope. Oral air pressure (Poral) was registered in a mouthpiece through which the endoscope was inserted into the larynx and to which the tubes were attached air-tightly. RESULTS: Compared with vowel phonation at habitual loudness, mean of maximal glottal width (max GW) increased by 44.1% for loud tube phonation and decreased by 1.8% for loud straw phonation, and mean absolute value of minimum GW time derivative dmin increased by 57.1% for tube and by 29.5% for straw suggesting faster glottal closing. Compared with loud vowel phonation, max GW increased by 22.6% for loud tube phonation, while it decreased by 16.6% for loud straw phonation. For the tube, dmindecreased by 7.6% and for the straw by 23.8%. Maximal acceleration (ACC) and deceleration (DC) values were larger for the tube and smaller for the straw than the values for both vowel phonations. CONCLUSIONS: IS, deduced from dmin, increased in loud SOVTEs compared to vowel phonation at a conversational loudness, but remained lower in loud SOVTEs than in loud vowel phonation, particularly with a narrow straw, which also reduced inertial forces, as suggested by the reduced ACC and DC.
ABSTRACT
PURPOSE: Coughing is related to voice problems, since it involves firm glottal closure, fast glottal opening, and high subglottic pressure and flow rate. In this study, the glottal area variation and movements of laryngeal structures during coughing and phonation are compared. METHODS: High-speed laryngoscopy recordings were made of a normophonic male participant with a healthy larynx producing a neutral vowel and coughing. Oral air pressure was registered in a mouthpiece, through which an endoscope was inserted into the pharynx. Electroglottography, acoustic, and pressure signals were recorded simultaneously. The glottal width variation at the membranous and cartilaginous parts of the glottis was derived from the high-speed images, and the strong vibration of the false vocal folds was also registered. RESULTS: In coughing, compared to ordinary vowel phonation in nearly the same sound pressure level (93-94 dB6cm), the glottal width was 25% larger at the middle of the vocal folds, the maximum glottal opening velocity was 39% higher, and the maximum glottal width declination rate during glottal closing was up to three times higher. The maximum acceleration was 40% higher, and the maximum deceleration was 47% higher. Fundamental frequency f0 was the highest (ca. 400 Hz) at the beginning of the first phase of a typical coughing process. During the last part of the coughing process, f0 decreased from ca. 250 Hz to ca. 85 Hz at the phonation offset. CONCLUSIONS: The remarkable increase in maximum glottal width declination rate implies much higher vocal fold loading in coughing compared to phonation.
ABSTRACT
OBJECTIVES: Water resistance voice therapy applies phonation into water through a tube. This study investigates how strenuous this therapy can be for the vocal folds in terms of impact stress (IS). It further examines whether it is possible to estimate the IS using the contact quotient (CQ) and maximum derivative from an electroglottogram (EGG). STUDY DESIGN: Experimental study. METHODS: A male participant sustained a rounded back vowel [u:] or [o:] at a comfortable speaking pitch and loudness, and phonated into a silicone "Lax Vox" tube submerged 2 cm in water. High-speed videolaryngoscopy was performed with a rigid scope. Oral air pressure (Poral) was registered in a mouthpiece through which an endoscope was inserted into the larynx. An EGG was recorded. RESULTS: The CQEGG from the EGG and the closed quotient from the glottal width (CQarea) increased, while the maximum glottal amplitude and absolute value of derivative minimum (dmin) and also the derivative maximum from the EGG decreased for phonation into water. Normalized amplitude quotient from the glottal width variation also decreased but the change was not significant. CONCLUSIONS: Based on the glottal area findings, water resistance therapy does not seem to increase vocal fold loading (in terms of increased IS) even if the increase of CQarea, and CQEGG suggest so. CQEGG may qualitatively correspond to that of area, but the reliability of CQ (from the glottal area or the EGG) and the maximum derivative from the EGG as estimates of IS in semiocclusion exercises warrant further studies.
