Investigation of singing with and without vibrato, using high-speed videolaryngoscopy and electroglottography

This study aimed to characterize the biomechanics of vibrato and non-vibrato phonation in professional singers, focusing on vocal fold oscillation patterns and cuneiform cartilage movements. Ten vocally healthy, professionally-trained, western classical singers were instructed to sustain the vowel [i:] without vibrato, with vibrato, and again without vibrato, for approximately two seconds for each quality. Data were collected via acoustic recordings, electroglottography (EGG), and transnasal high-speed videoendoscopy. After segmentation, glottal area waveforms (GAW) were analyzed, and temporal trajectories of fundamental frequency ( fo) and glottal parameters were compared. Cuneiform cartilage movement was tracked in three spatial dimensions using the videoendoscopic image sequences. The participants maintained a relatively stable mean fo across conditions, with no significant differences in open quotient (OQEGG and OQGAW) and closing quotient (ClQ) regarding vibrato and non-vibrato. During vibrato, most participants showed a higher OQ in vibrato fo minima than in maxima. Vibrato was associated with lower cepstral peak prominence and higher sound pressure level (SPL), and SPL courses inverse to fo modulation. The cuneiform tubercle tracking correlated to fo showed vertical and horizontal movements which followed, in one subject, an epiglottis forward positioning, presumably due to a tilting by cricothyroid muscle activity linked to the vibrato phenomenon.