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.     

Vocal Improvement After Voice Therapy in Unilateral Vocal Fold Paralysis

Unilateral vocal fold paralysis (UVFP) is associated with changes in acoustic and aerodynamic voice measurements and can have a significant impact on a patient's quality of life. Few objective data regarding the efficacy of voice therapy for UVFP exist. The aim of this study was to retrospectively analyze voice modifications in a group of patients with UVFP before and after voice therapy. Forty patients with UVFP of different etiology were included in the study. Each subject had voice therapy with an experienced speech/language pathologist twice a week; the mean number of sessions was 12.6. A multidimensional assessment protocol was used; it included videoendoscopy, the maximum phonation time (MPT), the GIRBAS scale, spectrograms and a perturbation analysis, and the Voice Handicap Index (VHI). Pre- and posttreatment data were compared by means of the Wilcoxon and Student's t tests. A complete glottal closure was seen in 8 patients before voice therapy and in 14 afterward. Mean MPT increased significantly. In the perceptual assessment, the difference was significant for five out of six parameters. A significant improvement was found on spectrographic analysis; as for perturbation analysis, the differences in jitter, shimmer, and noise-to-harmonic ratio values were significant. VHI values showed a clear and significant improvement. A significant improvement of voice quality and quality of life after voice therapy is an often reached and reasonable goal in patients with UVFP.     

Acoustic Analysis of Voice Quality with or without False Vocal Fold Displacement After Cordectomy

Conventional cordectomy by means of a laryngofissure is one of the therapeutic options for treatment of early glottic cancer. To improve the poor voice quality related to this kind of operation, many authors have developed different techniques to repair the mucosal defect. We analyzed voice quality acoustically and compared it after cordectomy alone and after cordectomy with the reconstruction of the vocal cord in a group of 14 patients affected by T1 glottic carcinoma. All the patients underwent postoperative speech therapy. Three patients who underwent cordectomy with reconstruction showed the presence of diplophonia, while two patients without reconstruction showed the presence of bitonality. The differences of the acoustic parameters (jitter, shimmer, harmonic-to-noise ratio) between the two groups of patients were not statistically significant. Reconstruction of the vocal cord does not seem to improve voice quality after cordectomy even in combination with postoperative speech therapy.     

Objective Voice Analysis for Dysphonic Patients: A Multiparametric Protocol Including Acoustic and Aerodynamic Measurements

The purpose was to determine the clinical value of a multiparametric objective voice evaluation protocol including acoustic and aerodynamic parameters measured mainly on a sustained /a/. This was done by comparison with perceptual analysis of continuous speech by a jury composed of 6 experienced listeners. Voice samples (continuous speech) from 63 male patients with dysphonia and 21 control subjects with normal voices were recorded and assesed by a jury of listeners. The jury was instructed to classify voice samples according to the G (overall dysphonia) component of the GRBAS score on a 4-point scale ranging from 0 for normal to 3 for severe dysphonia. Objective parameters were recorded on an EVA^® workstation. As usual with this type of system, parameters were measured mainly on a sustained /a/. Measured parameters included fundamental frequency (F₀), intensity, jitter, shimmer, signal-to-noise ratio, Lyapunov coefficient (LC), oral airflow (OAF), maximum phonatory time (MPT), and vocal range (range). Estimated subglottic pressure (ESGP) was determined on a series of /pa/. Discriminant analysis was performed to detect correlation between jury classification and combinations of parameters. Results showed that a nonlinear combination of only six parameters (range, LC, ESGP, MPT, signal-to-noise ratio, and F₀) allowed 86% concordance with jury classification. Discussion deals with the relative importance of the different objective parameters for discriminant analysis. Special emphasis is placed on two measurements rarely made in routine clinical workup, i.e., estimated subglottic pressure and Lyapunov coefficient.