Phonation in a straw. Experimental in vivo measurement of subglottic pressure with EVA@ device
Résumé
Introduction: We used vocal reeducation techniques based on exercices with a straw for more than 20 years. It seems to allows a gentle vibration of the vocal cords as well as a progression of the cordal ad- duction force proportional to resistance due to the straw. Our aim is to study the intraoral and subglottic pressures (IOP and SGP) and the modalities of the glottic vibration during these exercices. Method: The subject is a male vocal professional, with no voice pathology. The subglottic pressure was recorded by a probe placed between the first and the second tracheal ring and the intraoral pressure by a probe placed in the mouth. The voice is produced after a short expiration time, to obtain a sufficient and stable air flow, controlled with the hand at the extremity of the straw. Eight models of straw with different calibre and length were tested. The data were collected with the EVA@device and analysed with the Phonedit software (Sq-Lab, Aix en Provence). Results: A pressure gradient exists between the SGP and the IOP, variing with the voice frequency, and close to the phonation pressure threshold. The pressures are bigger when the straw calibre is small, the straw long and the frequency high. The vocal cord contact is differed when the straw is long. Conclusion: The phonation exercices with the straw require an output airflow control and thus allows an optimal adaptation of the SGP and vocal coaptation without risk for the free border of the vocal cords.