Objective Characterization of Phonation Type Using Amplitude of Flow Glottogram Pulse and of Voice Source Fundamental

Phonation type, a phonatory dimension ranging from hypofunctional/breathy to hyperfunctional/pressed, is important both from a clinical and acoustical point of view; hyperfunctional voice can lead to voice disorders and hypofunctional voice reduces text intelligibility. Five male singers sang diminuendo sequences of the syllable /pae/ and three of them also produced speech or singing samples with different phonation types which were rated for phonatory pressedness by a panel of voice experts. The sequences were analyzed by inverse filtering and the associated subglottal pressures were estimated as the oral pressures during the /p/ occlusion. The results showed strong quasi-linear correlations between the peak-to-peak amplitude of the flow glottogram (henceforth pulse amplitude) and mean subglottal pressure, mean airflow, and the level difference between the first and second voice source partials L₁-L₂. These correlations were found to vary systematically with phonation type. Regardless of phonation type, the correlation between the pulse amplitude and the amplitude of the voice source fundamental frequency was very close to 1.0. The level difference between the first and second spectrum partials L₁-L₂ in narrow-band long-term-average spectra of speech and singing was found to vary systematically with phonation type in a manner related to voice experts' ratings of perceived degree of pressedness. The findings support the assumption that the combination of subglottal pressure and level of the voice source fundamental is useful for an objective measure of phonation type.