Deviant vocal fold vibration as observed during videokymography: The effect on voice quality

Videokymographic images of deviant or irregular vocal fold vibration, inclu ding diplophonia, the transition from falsetto to modal voice, irregular vi bration onset and offset, and phonation following partial laryngectomy were compared with the synchronously recorded acoustic speech signals. A clear relation was shown between videokymographic image sequences and acoustic sp eech signals, and the effect of irregular or incomplete vocal fold vibratio n patterns was recognized in the amount of perceived breathiness and roughn ess and by the harmonics-to-noise ratio in the speech signal. Mechanisms ca using roughness are the presence of mucus, phase differences between the le ft and right vocal fold, and short-term frequency and amplitude modulation. It can be concluded that the use of simultaneously recorded videokymograph ic image sequences and speech signals contributes to the understanding of t he effect of irregular vocal fold vibration on voice quality.