Deviant Vocal Fold Vibration as Observed During Videokymography: The Effect on Voice Quality

Videokymographic images of deviant or irregular vocal fold vibration, including diplophonia, the transition from falsetto to modal voice, irregular vibration 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 speech signals, and the effect of irregular or incomplete vocal fold vibration patterns was recognized in the amount of perceived breathiness and roughness and by the harmonics-to-noise ratio in the speech signal. Mechanisms causing roughness are the presence of mucus, phase differences between the left and right vocal fold, and short-term frequency and amplitude modulation. It can be concluded that the use of simultaneously recorded videokymographic image sequences and speech signals contributes to the understanding of the effect of irregular vocal fold vibration on voice quality.     

Functional Analysis of Voice Using Simultaneous High-Speed Imaging and Acoustic Recordings

We present a comprehensive, functional analysis of clinical voice data derived from both high-speed digital imaging (HSDI) of the larynx and simultaneously acquired acoustic recordings. The goals of this study are to: (1) correlate dynamic characteristics of the vocal folds derived from direct laryngeal imaging with indirectly acquired acoustic measurements; (2) define the advantages of using a combined imaging/acoustic approach for the analysis of voice condition; and (3) identify new quantitative measures to evaluate the regularity of the vocal fold vibration and the complexity of the vocal output -- these measures will be key to successful diagnosis of vocal abnormalities. Image- and acoustic-based analyses are performed using an analytic phase plot approach previously introduced by our group (referred to as 'Nyquist' plot). Fast Fourier Transform (FFT) spectral analyses are performed on the same data for a comparison. Clinical HSDI and acoustic recordings from subjects having normal and specific voice pathologies, including muscular tension dysphonia (MTD) and recurrent respiratory papillomatosis (RRP) were analyzed using the Nyquist plot approach. The results of these analyses show that a combined imaging/acoustic analysis approach provides better characterization of the vibratory behavior of the vocal folds as it correlates with vocal output and pathology.     

Objective Voice Quality Analysis Before and After Onset of Unilateral Vocal Fold Paralysis

This study was designed to investigate objective voice quality measurements in unilateral vocal fold paralysis (UVFP) by eliminating intersubject variability. To our knowledge this is the first report objectively analyzing paralytic dysphonia as compared to the same voice before onset of UVFP. The voices of two male subjects were prospectively recorded before and after the onset of iatrogenic UVFP (thoracic surgery).The following acoustic measurements of the vowel /a/ were performed using the CSL and MDVP (Kay Elemetrics): jitter, shimmer, harmonics-to-noise ratio, cepstral peak prominence, the relative energy levels of the first harmonic, the first formant and the third formant, the spectral slope in the low-frequency zone (0-1 kHz and 0-2 kHz), and the relative level of energy above 6 kHz. Distribution of spectral energy was analyzed from a long-term average spectrum of 40 seconds of text. Laryngeal aerodynamic measurements were obtained for one patient before and after onset of paralysis using the Aerophone II (Kay Elemetrics). Pitch and amplitude perturbation increased secondary to UVFP, while the harmonics-to-noise ratio and the cepstral peak prominence decreased. A relative increase in the mid-frequency and high-frequency ranges and a decrease in the low-frequency spectral slope were observed. Mean airflow rate and intraoral pressure increased, and glottal resistance and vocal efficiency decreased secondary to UVFP. The findings of this self-paired study confirm some but not all the results of previous studies. Measures involving the fundamental and the formants did not corroborate previous findings. Further investigation with vocal tract modeling is warranted.