A study of temporal structure of glottal flow derivative estimates obtained via inverse filtering

This paper presents a comparative study of the temporal structure of the glottal flow derivative estimates in relation to an idealized view of voice source realizations as defined by Liljencrants-Fant´s model. Specifically, we endeavor to ascertain the extent by which Liljencrants-Fant´s model can be used to represent the glottal flow derivative estimates obtained via closed-phase pitch synchronous inverse filtering of recorded speech. The study includes several phonation types and two examples of voice pathology. The study has established the following. Due to the limited degrees of freedom, Liljencrants-Fant´s model is only capable of adequately representing the “coarse” glottal pulse structure. The “fine” structural elements can constitute a considerable part of a glottal flow derivative realization, and we have presented evidence that they contain information related to voice individuality. In addition, we have shown that LF-parameters do not always accurately portray significant events in the vocal fold dynamics.