On the effects of various vocal training methods on glottal resistance and efficiency. A preliminary report

The glottal resistance, i.e. the ratio of subglottic pressure to glottal flow, and the laryngeal efficiency, i.e. the ratio of oral acoustic power to aerodynamic subglottal power (multiplication of subglottig pressure and glottal flow), were measured for 11 subjects (3 males) with normal voices and for 1 female patient with glottal insufficiency in the repeated production of the nonsense word /paappa/ immediately before and after 1 min of vocal exercising with /beta:, m:/ and phonation into a narrow glass tube. For the subjects with normal voices the glottal resistance decreased in most cases and the laryngeal efficiency in half of the cases due to increased glottal flow. In contrast, for the patient the glottal resistance and efficiency increased due to decreased glottal flow. The results suggest that the vocal exercises instantly affected the control of the glottal width.