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

Abstract

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. 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. 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. 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.