Electroglottographic study of seven semi-occluded exercises: LaxVox, straw, lip-trill, tongue-trill, humming, hand-over-mouth, and tongue-trill combined with hand-over-mouth.

Introduction: Semi-occluded vocal tract exercises (SOVTE) are often used in voice clinics. SOVTE change the acoustic vocal tract impedance in relation to the glottis impedance, improving voice quality. However, differences among SOVTE, such as the number of vibration sources into the vocal tract, are often disregarded by clinicians.