Vocal intensity in falsetto phonation of a countertenor: an analysis by synthesis approach.

An analysis by synthesis paradigm was implemented to model glottal airflow and vocal tract acoustics for the falsetto phonation of a trained countertenor. Changes in vocal intensity were measured as a function of subglottal pressure, open quotient of the time-varying glottal airflow pulse, and formant tuning. The contributions of laryngeal adduction (open quotient of the glottal flow pulse) and of formant tuning to intensity change were derived from modeled data. The findings were: (1) Subglottal pressure accounted for almost 90% of the variation in SPL in falsetto phonation. (2) The open quotient of the glottal flow pulse was remarkably constant in these falsetto phonations, and thus did not affect vocal intensity significantly. (3) Formant tuning occurred in two out of nine possibilities for the vowel /a/. These instances did not support the concept of systematic exploitation of formant tuning.