The effect of viscosity changes in the vocal folds on the range of oscillation*
Summary
Changes in vocal fold oscillation threshold pressure were induced in excised canine larynges by experimentally causing fluid movement into and out of the vocal folds. The transport was facilitated by exposing the vocal folds to various osmotic solutions, and it was assumed that changes in hydration caused changes in the internal tissue viscosity. A range of oscillation threshold pressures was measured for each condition of hydration by varying length and glottal width. The oscillation threshold pressure shifted as predicted. Decreased hydration (increased viscosity) raised the threshold of oscillation, and increased hydration (decreased viscosity) lowered the threshold of oscillation. This apparently represents the first in vitro model for the study of the effect of viscosity changes of the internal environment of the vocal folds on phonation.
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Cited by (117)
The Efficacy of the NHS Waterpipe in Superficial Hydration for People With Healthy Voices: Effects on Acoustic Voice Quality, Phonation Threshold Pressure and Subjective Sensations
2024, Journal of VoiceCitation Excerpt :The effects of the hydration treatment on AVQI (v03.01) and its subparameters were somewhat against what one could expect on the basis of previous studies. According to Finkelhor and colleagues,3 by adding low-viscosity fluid, such as saline, to the tissue, the viscoelastic properties should improve. Indeed, this relationship has been verified by earlier studies.7,8
This study examined the efficacy of the NHS waterpipe as a superficial hydration treatment in voice production in healthy young women.
This is a prospective, single-blind, within- and between-subject experimental design.
Thirty six female university students (mean age 24.6 years, range 19–45 years) were recruited to the study. Participants were randomized to two experimental groups (E1 and E2) and a control group. E1 underwent hydration treatment with the NHS waterpipe filled with 0.9% saline that was immersed in a cup of heated water. E2 underwent a similar treatment but without heated immersion. The control group received no treatment. Acoustic Voice Quality Index (AVQI v03.01) and its subparameters, phonation threshold pressure, self-perceived phonatory effort and sensation of throat dryness was measured at three time points (before the intervention and immediately and 15 minutes after it).
The Tilt of the AVQI's subparameters increased significantly in the E1 (P = 0.027) and E2 groups (P = 0.027) after the intervention. Furthermore, the E1 group had significantly lower harmonics-to-noise-ratio values at the third measurement point compared to the E2 group (P = 0.023). These findings may result from fluid transported to the vocal fold level. The sensations of throat dryness decreased in the E1 (P = 0.001) and E2 groups (P < 0.0005) after the intervention. Perceived phonatory effort decreased statistically significantly at the final measurement point in the E1 (P = 0.002) and E2 (P = 0.031) groups. No variables changed in the control group.
The waterpipe seems to be efficient in hydrating vocal folds on single use. It seems to be more efficient when employed with a hot water bath, albeit slightly impairing some acoustic values in the short term. Without the heated fluid, it still seems to decrease sensations of throat dryness and affect acoustic voice quality. The waterpipe does not seem to have an effect on phonation threshold pressure, and it seems to lower self-perceived effort just as efficiently whether the waterpipe is employed using a hot water bath or not. Further research is needed to prove the efficacy of long-term usage and usage with voice patients.
Nasal Breathing Through a Damp Gauze Enhances Surface Hydration of the Vocal Folds and Optimizes Vocal Function
2023, Journal of VoiceThe present study proposes a direct surface hydration system based on nasal breathing through a damp gauze. The goal is to observe whether such direct hydration procedure positively modifies vocal fold functionality by improving voice quality and enhancing the mobility and pliability of the vocal fold mucosa.
Sixty-one young adults without voice problems were enrolled and were randomly divided into three double-blinded treatment groups. In the first group (the gauze group), participants breathed through the nose wrapped in a damp gauze for 10 minutes while doing vocal warm-up exercises to facilitate water penetration into the mucosal layers of the vocal folds. The second group (the exercise group) performed the same warm-up exercises as the gauze group for 10 minutes without hydration procedures. The third group (the control group) talked using their normal speaking voice for 10 minutes. The participants were evaluated before and after the treatment tasks with three tests: a laryngostroboscopic examination (ie, the glottic closure, the amplitude of the mucosal wave, and the maximum opening of the glottic space); voice acoustic analysis (multidimensional voice program); and a perceptual voice evaluation (GRBAS scale).
Results showed that after the use of a damp gauze, glottic closure, the amplitude of the mucosal wave, the maximum opening of the glottic space, the shimmer, and the B of GRBAS all improved.
Findings showed significantly better vocal results for the participants of the gauze group, suggesting the damp gauze procedure to be an effective, fast, and economical procedure to improve and optimize vocal fold functionality. It can be hypothesized that the obtained results are related to an improvement in vocal folds surface hydration and viscoelasticity.
Nebulized Saline Solution: A Multidimensional Voice Analysis
2023, Journal of VoiceTo verify the effect of nebulization on the voice of dysphonic and non-dysphonic individuals on acoustic, perceptual-auditory, aerodynamic, electroglottographic, laryngeal parameters and on the self-perception of vocal discomfort.
All the research subjects were submitted to vocal evaluation, laryngeal and voice self-perception. Then, the participants remained in vocal rest for a period of 10 minutes and the analysis mentioned above were again performed. After this first stage, the participants were submitted to the nebulization for a period of 10 minutes and the all analysis above were again performed. Descriptive analysis of the variables was carried. In the comparison of the pre- and post-nebulization groups, the Paired T-Student Test was used for variables with non-dysphonic distribution and the Wilcoxon Test for variables with asymmetric distribution. When categorical variables were evaluated (perceptual-auditory evaluation and laryngeal assessment), the Pearson's Chi-square test was used. In all analysis, a significance level of 5% was considered. The intra-rater agreement in the auditory-perceptual and perceptual-visual assessment was assessed using the AC1 statistic, using the R program. For this purpose, 20% of the voice samples and laryngeal images were replicated blindly and interpreted by the evaluators at the time evaluations.
The results of this research show that non-dysphonic individuals have more positive vocal and laryngeal effects after nebulization than dysphonic ones. It is also observed that the EGG measurement was the most sensitive to the effect of nebulization, with an increase in the Closed quotient (CQ) in all groups evaluated. Regarding acoustic measurements, it is noted that the effect of nebulization in men is more evident than in women. After nebulization, there was an increase in fundamental frequency in the group of non-dysphonic women and dysphonic and non-dysphonic men. A decrease in the amplitude perturbation quotient values is observed in all groups, besides a reduction in the pitch perturbation quotient values after nebulization in non-dysphonic men groups. There was improves aerodynamic efficiency in groups of dysphonic and non-dysphonic men and in the self-perception of vocal discomfort in all groups studied after the hydration procedure. The results of this study demonstrate a significant improvement in the mucosal wave after nebulization in the groups of women and men who are not dysphonic.
The nebulization procedure with saline solution improves acoustic measurements, the electroglottographic closed quotient and vocal self-perception of dysphonic and non-dysphonic women and men. Nebulization increases the mucosal wave of the vocal folds in non-dysphonic women and men and improves the aerodynamic efficiency of men.
A systematic review and meta-analysis on the outcomes of type I thyroplasty in the irradiated neck
2023, American Journal of Otolaryngology - Head and Neck Medicine and SurgeryType I thyroplasty has been well-documented as a safe and effective treatment modality for vocal fold motion impairment, as well as other select cases of persistent glottic insufficiency. However, history of prior radiation to the neck has traditionally been viewed as a relative, if not formal contra-indication to this procedure. The objective of this systematic review was to analyze all available data in the literature on type I thyroplasty in previously irradiated patients and perform a meta-analysis assessing whether complications and revision rates are significantly different between radiated and non-irradiated patients. Secondary outcomes were to compare voice outcomes between these cohorts.
Several databases were screened for relevant citations using the PICO process. The quality of studies and risk of bias were evaluated using the MINORS scoring system. Main endpoints for analysis in this study were complication rate and revision rate. Secondary endpoint was reported voice outcome.
Three articles were included in the analysis. Zero major complications were reported, including no instances of implant extrusion or explantation. There was an 11.8 % rate of minor complications. There were similar rates of revision between radiation and control groups. There was no significant difference in voice outcomes between groups. The average MINORS score of the studies suggested a high risk of bias.
Based on limited quality evidence, this review suggests that type I thyroplasty is safe and feasible in carefully selected irradiated patients, with comparable complication and success rates as their non-irradiated cohorts. Further large-scale studies are warranted.
Vocal Hygiene in Collegiate Singers—Does Formal Training Relate to Practices?
2021, Journal of VoiceBackground: Vocal hygiene is vitally important for protecting vocal quality and promoting vocal longevity. It includes adequate hydration, avoidance of environmental irritants, and refraining from phonotraumatic behaviors such as screaming, excessive talking, and throat clearing. Formal singing training in addition to enhancing singing techniques, is also assumed to promote good vocal hygiene. Consequently, we investigated whether collegiate singers with formal training are more likely to practice good vocal hygiene habits than untrained collegiate singers. Methods: We completed a prospective cohort study, where collegiate singers at Stanford University were voluntarily enrolled in an annual vocal health clinic. Full laryngeal exams were performed and demographic information, formal vocal training status, and information on vocal hygiene habits were obtained through questionnaires. The results were then analyzed by grouping singers as “untrained” if less than 1 year of formal training, and “trained” if greater than a year. Results: A total of 82 singers were included for analysis, with 49 (59.8%) having greater than one year of formal training. Trained singers were more likely to employ a primary musical singing style of classical or operatic singing compared to untrained singers who were more likely to utilize “R&B” (P < 0.001). No significant differences were found between groups for hydration practices (P = 0.20), caffeine consumption (P = 0.73), warm up practices (P = 0.08), and phonotraumatic behaviors. Alcohol consumption, smoking tobacco, marijuana, e-cigarette usage was similar between groups. Overall, 11% of our sample reported intermittent less than daily marijuana use, with one singer reporting daily consumption. None of the singers in this sample used e-cigarettes. These rates are noticeably lower than the agematched United States population. Perceptions of cigarettes, marijuana, electronic cigarettes, alcohol, and caffeine were also the same between groups, with the vast majority of singers perceiving these agents as harmful to the voice (64%–100% depending on the agent). No laryngeal pathology was identified during laryngeal examination of any singers. Conclusions: Vocal hygiene habits are similar between trained and untrained collegiate singers. This likely relates to a desire for vocal longevity irrespective of prior training. This may dispel the long-held assumption that formal training was necessary to develop good vocal habits. We do however, present a very homogenous, highly educated sample of collegiate singers from Stanford University, having significantly less at-risk behavior than their aged-matched counterparts in the general US population. A lack of laryngeal pathology despite extensive vocal demands may also be reflective of good vocal hygiene habits.
Outcomes of voice therapy in children with benign vocal fold lesions
2020, International Journal of Pediatric OtorhinolaryngologyThis study aims to examine the effect of voice therapy on dysphonia on children with benign vocal fold lesions, as measured by perceptual evaluation using the Consensus Auditory Perceptual Evaluation of Voice (CAPE-V) and acoustic and aerodynamic measures (jitter, shimmer, noise-to-harmonic ratio, phonation threshold pressure, mean airflow during voicing, subglottic pressure during comfortable phonation).
Prospective disease-specific outcomes database.
Subjects identified in the database consisted of 28 children (14 male, 14 female) between the ages of three and eighteen. Pre- and post-therapy perceptual, acoustic and aerodynamic measures were compared using two-sided paired t-test.
There was a statistically significant difference in perceptual ratings of voice quality (p < .001) and in phonation threshold pressure before and after therapy (p = .034). While acoustic measures improved after therapy, changes were not statistically significant.
Children with dysphonia secondary to benign vocal fold lesions showed positive change in perceptual ratings of voice quality and in phonation threshold pressure after voice therapy.
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Presented at the Sixteenth Symposium: Care of the Professional Voice, June 1987.