The Influence of Voice Training on Vocal Learner's Objective Acoustic Voice Components.

OBJECTIVE: Acoustic parameters of voice were studied in music majors throughout 18 months of training to understand the influence of voice training on voice. METHODS: Twenty-three students from Xiamen Music School between 12 and 15 years old were enrolled. Acoustic examination was performed three times- every 6 months for 18 months. Various traditional acoustic parameters were measured, including dysphonia severity index (DSI), jitter, and D-value of vocal range. Nonlinear dynamic measures were also measured, including diffusive chaos to construct voice type component profiles (VTCPs), spectrum convergence ratio, and nonlinear energy difference ratio. The results were analyzed by multivariate analysis of variance. RESULTS: Over the study duration, there was an improvement of DSI (P = 0.002), and D-value of vocal range (P = 0.000). Among nonlinear parameters, only voice type component data demonstrated significant changes during the study duration. Both Voice Type Component 1(VTC1) and VTC3 values differed from Time 1 to Time 2 as well as from Time 1 to Time 3. The proportion of VTC1 in samples generally decreased, while VTC3, representative of aperiodicity, increased. Both nonlinear energy difference ratio and spectrum convergence ratio exhibited no significant changes throughout the study. CONCLUSION: Professional voice training can improve DSI and D-value of vocal range in singers' voices. These parameters have potential to be used for voice training evaluation and screening. Many nonlinear parameters did not detect differences in the healthy voices studied, but VTCPs created using intrinsic dimension present a valuable new method, visualizing increases in aperiodicity of the speaking voices after professional voice training.

Do the Nonlinear Dynamic Acoustic Measurements, Nonlinear Energy Difference Ratio and Spectrum Convergence Ratio, Correlate with Perceptual Evaluation of Esophageal Voice Speakers?

BACKGROUND: The acoustic assessment of phonation after total laryngectomy is challenged by signal aperiodicity which makes frequency-based acoustic measures less reliable. This is important for patients who use esophageal voice since voice samples mostly include type III (highly aperiodic) and 4 (chaotic) signals. As such, using non-linear measures, which are better suited for aperiodic phonation, may be useful to investigate the relationship between acoustic signal characteristics and perception of esophageal voice quality. OBJECTIVES: This study aimed to investigate whether nonlinear dynamic acoustic methods, nonlinear energy difference Ratio (NEDR) and spectrum convergence ratio (SCR), were correlated with perceptual measures in subjects who used esophageal phonation. METHODS: Thirty-one subjects who had undergone total laryngectomy and use esophageal voice as a rehabilitation method were included in this study. Expert and non-expert raters listened to the esophageal voice samples from the subjects and rated vowels and connected speech samples on a scale from 1 to 7 on dysphonia severity and intelligibility. In addition, non-linear acoustic analysis was performed to calculate NEDR and SCR. Analysis from the raters was compared to the non-linear acoustic analysis to find the correlation between the variables. RESULTS: There were no significant correlations between any of the non-linear acoustic measures NEDR and SCR and the perceptual ratings at the significance level of 0.05. Correlations were calculated for each acoustic measure among the expert raters and among the non-expert raters in both connected speech samples and sustained vowel fragments. CONCLUSIONS: In conclusion, the nonlinear dynamic acoustic analyses of spectrum convergence ratio and nonlinear energy difference ratio do not have a significant correlation with perceptual measures of esophageal voice.

Evaluating the Voice Type Component Distributions of Excised Larynx Phonations at Three Subglottal Pressures.

Purpose The excised canine larynx provides an advantageous experimental framework in the study of voice physiology. In recent years, signal processing methods have been applied to analyze phonations in excised canine larynx experiments. However, phonations have a highly complex and nonstationary nature corresponding to different proportions of regular and chaotic signal elements. Current nonlinear dynamic methods that are used to assess the degree of irregularity in the voice fail to recognize the distribution of voice type components (VTCs). Method Based on measures of intrinsic dimension, this article presents a method to analyze the VTC distribution of phonations in excised canine larynx experiments. Thirty-nine phonation samples from 13 excised canine larynges at three different subglottal pressures were analyzed. Results Phonation produced with subglottal pressures above phonation instability pressure (PIP) and below phonation threshold pressure (PTP) resulted in high proportions of Voice Types 3 and 4, characterized by chaotic and noisy signals. Phonation produced with pressure between PTP and PIP contained mostly Type 1 voice, characterized by a regular and nearly periodic signal. Mean proportions of all VTCs varied significantly in comparisons of phonations produced with Sub-PTP and PTP as well as in comparisons of phonations produced with PTP and PIP. Conclusions Across all VTCs, the VTC profiles of normal and abnormal phonation differ significantly. Normal phonation is strongly associated with VTC1 (Voice Type Component 1), whereas abnormal phonation exhibits increased VTC4 (Voice Type Component 4). The study further demonstrates the ability of intrinsic dimension to successfully detect multiple voice types in an acoustic signal and highlights the need for expanded use of intrinsic dimension in human voice. Supplemental Material https://doi.org/10.23641/asha.14417585.

Evaluation of Diffusional Characteristics and Microstructure in Unilateral Vocal Fold Paralysis Using Diffusion Tensor Imaging.

OBJECTIVE: To investigate the value of diffusion tensor imaging (DTI) in the evaluation of vocal fold tissue microstructure after recurrent laryngeal nerve (RLN) injury. METHODS: Six canines were divided into 2 groups: a unilateral vocal fold paralysis group (n = 4) and a control group (n = 2). The RLN was cut in the unilateral vocal fold paralysis group, and no intervention was applied in the control group. After 4 months, the canines' larynges were removed and placed in a small animal magnetic resonance imaging (MRI) system (9.4T BioSpec MRI; Bruker, Germany). After scanning, the vocal folds were isolated, sectioned, and stained. The slides were then analyzed for the cross-sectional area and muscle fiber density through feature extraction technology. Pearson correlation analysis was performed on the DTI scan and histological section extraction results. RESULTS: In the vocal fold muscle layer, the fractional anisotropy (FA) of the unilateral RLN injury group was higher than that of the control group, and the Tensor Trace was lower than that of the control group. This difference was statistically significant, P < .05. In the lamina propria, the FA of the unilateral RLN injury group was lower than that of the control group, P > .05, and the Tensor Trace was lower than that of the control group, P < .05. The muscle fiber cross-sectional area of the RLN injury group was significantly smaller than the control group with statistical significance, P < .05, and the density of muscle fibers was lower, P < .05. The correlation coefficient between FA and the cross-sectional area was -0.838, P = .002, and .726; P = .017 between Tensor Trace and the cross-sectional area. CONCLUSION: Diffusion tensor imaging is an effective method to assess the changes in the microstructure of atrophic vocal fold muscle tissue after RLN injury.