Phonation into a tube, also known as the "resonance tube method," consists of a group of exercises that make use of semi-occlusions of the vocal tract, including lip trills, tongue trills, and humming. These exercises were originally devised to treat velopharyngeal insufficiency, and were found to be useful also for voice training and therapy. The beneficial outcomes of these exercises have been reported for various kinds of voice disorders, and their efficacy has been theoretically proven by computer simulation.
On the other hand, most studies on semi-occluded exercises used vocal tract models without adequate practical data. To address this problem, this study employed a stroboscope to visualize the shape of vocal fold vibration during phonation into a tube in patients with vocal fold nodules. Practical observations showed that vocal fold vibration amplitudes increase immediately. This result indicates that the exercises make the voice more efficient, as shown in the computer simulation.
Although a larger sample pool and more extensive follow-up would be necessary in order to make a general and definitive conclusion, we positively recommend the resonance tube method for patients with vocal fold nodules because it is easy to access and continue at home.
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