Effects of a simulated system of straw phonation on the complete phonatory range of excised canine larynges.

PURPOSE: This study investigated the effects of straw phonation therapy on the aerodynamic and acoustic parameters of the vocal folds at different levels of elongation and subglottal pressure. METHODS: 20 excised canine larynges were used in both experimental (straw phonation therapy simulation) and control conditions. Aerodynamic parameters, including phonation threshold pressure (PTP), phonation instability pressure (PIP), phonation pressure range (PPR), phonation threshold flow (PTF), phonation instability flow (PIF), phonation flow range (PFR), were obtained at different levels of vocal fold elongation (0%, 10%, 20%). Acoustic parameters, including fundamental frequency (F0), jitter, shimmer, signal noise ratio (SNR) were detected at different levels of vocal fold elongation (0%, 10%, 20%) and subglottal pressure (15 cmH2O, 20 cmH2O, 25 cmH2O). RESULTS: Significant decreases in PTP and PTF and significant increases in PIP, PIF, PPR, and PFR occurred in experimental condition at all levels of elongation when compared with control condition. However, no significant changes of acoustic parameters were obtained between conditions at all levels. CONCLUSION: At different levels of vocal fold elongation, straw phonation not only lowered the onset of normal voice, but also elevated the onset of chaotic voice, indicating a better voice economy and voice control. Moreover, the improved phonatory range demonstrated that straw phonation had the potential to prevent voice users who have high voice demand from voice fatigue and vocal damage.

Effects of Varying Lengths and Diameters During Straw Phonation on an Excised Canine Model.

OBJECTIVE/BACKGROUND: Straw phonation, a well-established method of vocal exercise, started over 100 years ago. However, some of the most basic questions about best practices remain including the ideal extension length and the ideal restriction (semiocclusion) diameter. This study aims to help answer these questions by looking at both separately, with all other variables controlled. METHODS: Four (4) straws with lengths of 5, 25, 50, and 75 centimeters and 4 restrictions with diameters of 3, 9, 15, and 21 mm were tested, separately. They were attached to the end of a simulated vocal tract which was then affixed to an excised canine larynx. Airflow was increased until the larynges achieved self-sustained phonation then aerodynamic, acoustic, and electroglottographic data were collected. RESULTS: There was a significant decrease in the phonation threshold pressure using the 5 and 25 cm straw lengths and the 9 and 15 mm restrictions. The phonation threshold flow and contact quotient saw insignificant changes, except in the case of the 3 mm restriction. DISCUSSION: It is theorized that the increased inertive reactance helps to decrease phonation threshold pressure. By controlling for all other variables, the effects of the length or diameter of the straw can be analyzed in isolation. These results narrow the significant range of lengths and diameters used in straw phonation.