Direct measurement of pressures involved in vocal exercises using semi-occluded vocal tracts.

The aim of this study was to rank vocal exercises using semi-occluded vocal tracts (SOVT) as a function of their effect on subglottal pressure (SGP) and on transglottal pressure (TGP). Direct measurements were performed in two healthy females. The correct realization of vocal exercises was controlled by maintaining a constant airflow at the phonation onset. TGP varied from 1.8 to 5.9 hPa among SOVT, in the same range as phonation threshold pressure values. SGP varied among subjects from 19.4 for 2-mm straw to 3.2 hPa for closed vowel. SOVT could be ranked in voice rehabilitation from the greatest to the smallest effects on SGP as following: 1) 2-mm straw; 2) 5-mm straw and fricative /v/; 3) 8-mm straw and nasals /m/ and /n/; 4) vowel /i/.