Aims: To demonstrate physiological changing of vocal tract's structures during overtone singing with commercial magnetic resonance imaging (MRI) Fast Imaging Employing Steady State Acquisition (FIESTA) dynamic sequence.
Methods and materials: A 1.5 T MRI with a 16 channel head-and-neck coil and a FIESTA sequence were used. A temporal resolution of 0.155 sec (7 image/s). A single professional singer was studied. The MR acquisition is made while the singer performed a predetermined singing sequence. Three different overtone singing techniques were examined (L-technique, J-technique, and NG technique) and one effect (Ezengileer) applied to L-technique. For each overtone technique we evaluated MRI movement of lips, tongue, velopharyngeal closure, and relationship among tongue and pharyngeal posterior wall/soft palate. To cancel the noise over-imposed, the dynamic MRI was subsequently dubbed in studio with the audio of the preset overtone sing. Dubbed MR images were analyzed with an Overtone Analyzer Software and different sound frequencies were identified and pointed out as colored lines.
Results: This study shows that different overtone techniques are related to a specific conformation of tongue, lips, soft and hard palate and motion's relation changing between them. Only a correct conformation of vocal tract's structure allows resonance and so to hear desired fundamental and harmonic pitch in overtone singing.
Conclusion: The preliminary data of our study demonstrates that FIESTA dynamic MRI sequence can be used to depict changing of position of vocal tract's structure in overtone singing techniques with a good temporal and anatomic resolution.
Keywords: FIESTA MRI; MRI; Overtone singer; Speech science; Vocal tract; Voice physiology.
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