The effect of phonation into a straw on the vocal tract adjustments and formant frequencies. A preliminary MRI study on a single subject completed with acoustic results

Abstract

Phonation into a straw is used in voice training and therapy. This study investigated its’ effects on the vocal tract adjustments. Magnetic resonance images were taken from one female phonating first on [a:], then into a plastic drinking straw and then again on [a:]. Acoustic samples were recorded from her and 10 other females. The samples were analyzed for fundamental frequency, sound pressure level (SPL), five lowest formant frequencies ( F 1– F 5) and SPL of the speaker's formant cluster range (2.5–4.5 kHz). During and after phonation into a straw, the midsagittal area of the vocal tract increased and the velar closure improved. The ratio of the transversal area of the lower pharynx over that of the epilarynx increased both during (27%) and after the straw (20%). The overall SPL and the SPL of the speaker's formant cluster increased. The frequencies of F 2, F 4 and F 5 decreased, while F 3 increased. The distances between F 4 and F 3 and F 5 and F 4 decreased by 49%. For the 10 subjects, F 3 increased, F 4 decreased and the distance between F 3 and F 4 decreased significantly. The results suggest that exercising with a straw helps establishing a speaker's formant cluster, which increases loudness and thus improves vocal economy.