The multidimensional nature of pathologic vocal quality

Although the terms "breathy" and "rough" are frequently applied to pathological voices, widely accepted definitions are not available and the relationship between these qualities is not understood. To investigate these matters, expert listeners judged the dissimilarity of pathological voices with respect to breathiness and roughness. A second group of listeners rated the voices on unidimensional scales for the same qualities. Multidimensional scaling analyses suggested that breathiness and roughness are related, multidimensional constructs. Unidimensional ratings of both breathiness and roughness were necessary to describe patterns of similarity with respect to either quality. Listeners differed in the relative importance given to different aspects of voice quality, particularly when judging roughness. The presence of roughness in a voice did not appear to influence raters' judgments of breathiness; however, judgments of roughness were heavily influenced by the degree of breathiness, the particular nature of the influence varying from listener to listener. Differences in how listeners focus their attention on the different aspects of multidimensional perceptual qualities apparently are a significant source of interrater unreliability (noise) in voice quality ratings

Functional testing of a tissue-engineered vocal fold cover replacement

ABSTRACT OBJECTIVES: Tissue engineering may provide a treatment for severe vocal fold scars. This study quantifies mechanical properties and demonstrates vibration of a tissue-engineered vocal fold cover replacement. METHODS: Tissue-engineered constructs were produced from fibrin and adipose-derived stem cells. Optimized bilayered constructs contained epithelial and mesenchymal cell phenotypes in a stratified geometry. For comparison, homogeneous constructs did not have epithelial differentiation. Elastic modulus was determined using indentation. Immunohistochemical labeling for type I collagen was performed. A bilayered construct was also tested in phonation in an excised larynx model. RESULTS: Bilayered vocal fold cover replacements had indentation moduli similar to human vocal fold covers (mean construct modulus 6.8 kPa). Collagen deposition occurred in the middle of the construct. Homogeneous constructs had a mean modulus of 8.3 kPa, and collagen was concentrated at the surface. An excised larynx with unilateral vocal fold cover replacement phonated and exhibited mucosal waves at physiologic airflow. CONCLUSION: Bilayered tissue-engineered constructs were produced that exhibited indentation modulus, microstructure, and vibration similar to that exhibited by human vocal fold covers. © 2010 American Academy of Otolaryngology-Head and Neck Surgery Foundation. All rights reserved. T issue engineering may provide treatment for vocal fold scarring. We propose that replacing the entire vocal fold cover may be more effective than addressing only the lamina propria in severe cases. We have produced a stratified tissue-engineered construct resembling the vocal fold epithelium and lamina propria using adipose-derived stem cells (ASC) in fibrin. 1 With epidermal growth factor (EGF) and an air interface, the ASC differentiate into epithelial cells near the surface and mesenchymal cells within the construct bulk. We now assess whether this candidate cover replacement has mechanical and vibratory properties similar to the native vocal fold. Methods Institutional Review The UCLA Institutional Review Board approved the use of donated human lipoaspirate, cryoprecipitate, and cadaveric larynges. Fibrin-ASC Constructs ASC were isolated from lipoaspirate and cultured. 2 For fibrin constructs, cryoprecipitate was mixed with ASC and thrombin. 1 Three hundred L was polymerized within Transwell inserts (Cole-Parmer, Vernon Hills, IL), then concentrated ASC were added to the surface. Half of the constructs were cultured with an air interface and were supplied 10 ng/mL EGF and 10% fetal bovine serum in the culture medium (bilayered group). The remaining constructs had EGF-free culture medium and were submerged under liquid (homogeneous group). All were harvested at two weeks. For immunohistochemistry, samples were frozen, sectioned, and fixed onto slides. After blocking with goat serum, a rabbit antibody to type I collagen (DAKO, Denmark) was applied and detected with a goat-anti-rabbit fluorescein isothyocyanate-conjugated antibody. For a phonating construct, a 3 ϫ 1 cm rectangular well was scored in the base of a sterile culture dish. Cryoprecipitate-ASC-thrombin mixture was pipetted into the well. After the mixture gelled, additional concentrated ASC were added to the surface. Culture medium containing EGF bathed the gel on all sides but not on the surface. The sample was harvested at three weeks. Indentation A 1-mm indenter tip mounted onto a force transducer indented the construct surface in 0.025-mm steps until reach

A comparison of type I thyroplasty and arytenoid adduction

Glottal incompetence is a common laryngeal disorder causing impaired swallowing and phonation. The resultant voice has been characterized as weak and breathy with a restricted pitch range. Currently, medialization thyroplasty and arytenoid adduction are two of the surgical treatments for patients with glottal incompetence. However, few studies have evaluated the changes in objective measures of speech with type I thyroplasty and arytenoid adduction. In this study, 59 patients with glottal incompetence underwent either type I thyroplasty or arytenoid adduction. Acoustic (jitter, shimmer, and harmonics-to-noise ratio) and aerodynamic (airflow, subglottic pressure, and glottal resistance) measures were obtained both pre- and postoperatively. No significant differences were found among acoustic or aerodynamic measures for operation type. However, a significant pre/postsurgery effect was observed for translaryngeal airflow. In addition, no significant differences were found among the measures for patients with traditional compared with nontraditional operative indications. Patients who developed glottal insufficiency due to previous laryngeal surgery (e.g., vocal fold stripping) demonstrated no statistically significant improvement in acoustic or aerodynamic measures following thyroplasty or arytenoid adduction. © 1995 Lippincott-Raven Publishers, Philadelphia

Development of the ex vivo laryngeal model of phonation.

Objectives/hypothesisThe direct study of human phonation is limited by the invasive and painful nature of human laryngeal neuromuscular manipulation. As a platform for the study of human phonation, indirect models have been utilized for decades such as animal, cadaveric, and computational. We sought to develop a research method allowing direct scientific control of virtually living larynges to expand our ability to understand human phonation.Study designCanine and porcine models.MethodsNineteen canine larynges were surgically removed and reperfused with progressively adapting methodologies to create ex vivo phonation.ResultsFull neuromuscular stimulation and phonation were ultimately achieved in the ex vivo larynx. As compared with alternative perfusate solutions, heparinized whole blood was found to result in the most robust neuromuscular response. Modification of the reperfusion technique from a continuous flow to a pulsatile pump system resulted in dramatic increases in neuromuscular response and longevity of the organ. The experimental findings were repeated to demonstrate reliability of the ex vivo model.ConclusionsThe ex vivo larynx model is demonstrated to be a repeatable platform for phonatory research. The process of development has been comprehensively described in the present report. Although the described experimental model was designed for phonatory research, this model can be readily adapted for investigations of organ transplant preservation techniques, effects of organ ischemia, and neuromuscular reinnervation capabilities.Level of evidenceNA

Exit jet particle velocity in the in vivo canine laryngeal model with variable nerve stimulation

This study extends previous work on exit jet particle velocity in the in vivo canine model of phonation by measuring air particle velocity at multiple locations in the midline of the glottis and across multiple levels of recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) stimulation. In a second experiment, exit jet particle velocity was measured at midline and offmidline positions with constant levels of RLN and SLN stimulation. In this study, peak particle velocity was higher at the anterior commissure than at the posterior commissure in the midline of the glottis, and peak particle velocity was higher at the midline than at offmidline positions. In addition, increasing levels of RLN stimulation resulted in increasing peak particle velocity; however, increasing levels of SLN stimulation failed to produce a uniform effect on peak particle velocity

Comparison of voice analysis systems for perturbation measurement

Dysphonic voices are often analyzed using automated voice analysis software. However, the reliability of acoustic measures obtained from these programs remains unknown, particularly when they are applied to pathological voices. This study compared perturbation measures from CSpeech, Computerized Speech Laboratory, SoundScope, and a hand marking voice analysis system. Sustained vowels from 29 male and 21 female speakers with mild to severe dysphonia were digitized, and fundamental frequency (Fo), jitter, shimmer, and harmonics- or signal-to-noise ratios were computed. Commercially available acoustical analysis programs agreed well, but not perfectly, in their measures of Fo. Measures of perturbation in the various analysis packages use different algorithms, provide results in different units, and often yield values for voices that violate the assumption of quasi-periodicity. As a result, poor rank order correlations between programs using similar measures of perturbation were noted. Because measures of aperiodicity apparently cannot be reliably applied to voices that are even mildly aperiodic, we question their utility in quantifying vocal quality, especially in pathological voices. © 1996, American Speech-Language-Hearing Association

Effects of RLN and SLN stimulation on glottal area

In vivo canine experiments have demonstrated that vocal fold stiffness varies proportionately with changing levels of recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) stimulation. This study evaluated the morphologic changes in the glottis at varying levels of nerve stimulation and the presumed effects on laryngeal air particle velocity. Stroboscopic data from the in vivo canine model of phonation were examined under varying conditions of RLN and SLN stimulation. Computerized analysis of stroboscopic Images was used to reconstruct the glottal area vs. time waveforms. As RLN stimulation increased, glottal area per cycle decreased (p \u3c 0.05). However, as SLN stimulation increased, glottal area per cycle increased (p \u3c 0.05). These results support the hypothesis that increasing RLN stimulation at similar levels of SLN stimulation produces an increase in air particle velocity, whereas an increase in SLN stimulation causes a decrease in air particle velocity. © 1994, Official journal of the American Academy of Otolaryngology–Head and Neck Surgery Foundation. All rights reserved

Preliminary Study of the Open Quotient in an Ex Vivo Perfused Human Larynx

ImportanceScientific understanding of human voice production to date is a product of indirect investigations including animal models, cadaveric tissue study, or computational modeling. To our knowledge, direct experimentation of human voice production has previously not been possible owing to its invasive nature. The feasibility of an ex vivo perfused human phonatory model has recently allowed systematic investigation in virtually living human larynges with parametric laryngeal muscle stimulation.ObjectiveTo investigate the association between adductor muscle group stimulation and the open quotient (OQ) (the fraction of the cycle during which the glottis remains open) of vocal fold vibration.Design, setting, and participantsAn ex vivo perfused human tissue study was conducted at a physiology laboratory. Human larynx recovered from organ donors within 2 hours of cardiac death was used. The study was performed on May 19, 2014; data analysis took place from June 1, 2014, to December 15, 2014.InterventionsPerfusion with donated human blood was reestablished shortly after cardiac death. Ex vivo perfused human phonation was then achieved by providing subglottal airflow under graded neuromuscular electrical stimulation bilaterally to the intrinsic adductor groups and cricothyroid muscles.Main outcomes and measuresPhonation resulting from the graded states of neuromuscular stimulation was evaluated using high-speed vibratory imaging; the OQ was derived through digital kymography and glottal area waveform analysis.ResultsDuring constant glottal flow, a stepwise increase in adductor muscle group stimulation decreased the OQ. Quantitatively, OQ values decreased with increased stimulation levels from 2 V (OQ, 1) to 5 V (OQ, 0.68) and reached a lower limit of 8 V (OQ, 0.42). Increased stimulation above maximal muscle deformation was unable to affect OQ beyond this lower limit.Conclusions and relevanceTo our knowledge, a negative association between adductor muscle group stimulation and phonatory OQ has been demonstrated for the first time in a neuromuscularly activated human larynx. Further experience with the ex vivo perfused human phonatory model will aid in systematically defining this causal relationship

Safety of percutaneous injection of bovine dermal crosslinked collagen for glottic insufficiency.

OBJECTIVE: Our aim was to review the safety of percutaneous injection laryngoplasty using bovine crosslinked collagen, focusing specifically on two often-stated concerns: injecting patients who are taking the anticoagulant medication warfarin, and injecting patients without prior skin hypersensitivity testing. STUDY DESIGN AND SETTING: Retrospective chart review of injection laryngoplasty performed between 1997 and 2006 at the University of California, Los Angeles. RESULTS: The study group consisted of 895 patients who underwent 1290 injection laryngoplasty procedures. No bleeding complications were noted in 59 patients taking warfarin. No allergic complications were reported in 845 patients who did not undergo skin hypersensitivity testing before injection laryngoplasty. CONCLUSION: Percutaneous bovine crosslinked collagen injection laryngoplasty is safe in patients taking warfarin. Skin testing for hypersensitivity does not appear to be necessary before injection. SIGNIFICANCE: Patients on warfarin are candidates for injection laryngoplasty without the need to discontinue the medication. Eliminating skin hypersensitivity testing before percutaneous bovine crosslinked collagen injection laryngoplasty allows for a prompt treatment of glottic insufficiency