Analysis of voice production in breathy, normal and pressed phonation by comparing inverse filtering and videokymography

The present study addresses comparison of two analysis methods of voice production, inverse filtering and videokymography (VKG). Speech data were collected from two male speakers using sustained phonation during laryngoscopy (sound corresponding approximately to the vowel /ä/). The type of phonation was varied between breathy, normal, and pressed. From the waveforms given by inverse filtering, the time length between the positive and negative peak of the glottal flow derivative and the length of the fundamental period was measured. The length of the open phase and the length of the fundamental period was measured from the VKG-images. The results suggest that the time length between the positive and negative peak of the flow derivative equals the length of the open phase of the VKG-image (i.e., the time difference between the opening and closing of the middle line of the vocal folds) for phonations with complete closure of the glottis.