Amplitude Of Vocal Fold Vibration Research Articles

Regenerative Effect of a 532-nm Diode Laser on Vocal Fold Scar in a Rabbit Model

We evaluated the regenerative effect of a 532-nm diode laser in a rabbit model of vocal fold scarring. This study included 40 male New Zealand white rabbits: 20 underwent vocal fold scar surgery only (control group) and 20 underwent 532-nm diode laser glottoplasty 1 month after vocal fold scar surgery (glottoplasty group). Histological and high-speed video analyses of vocal fold vibration were performed 1 month after vocal fold scar surgery and laser glottoplasty. The maximum amplitude of vocal fold vibration and dynamic glottal gap was measured. Real-time polymerase chain reaction (PCR) was also performed to evaluate scar regeneration and wound remodeling. Transforming growth factor (TGF)-ß1, interleukin (IL)-6, procollagen-1, matrix metalloproteinase (MMP)-2, MMP-9, hyaluronan synthase (HAS)-2, and HAS-3 levels were measured. The maximum difference in amplitude of vocal fold vibration and the dynamic glottal gap was significantly greater in the glottoplasty than in the control group. Real-time PCR revealed significantly higher MMP-2, MMP-9, HAS-2, and HAS-3 levels, and lower TGF-ß1, IL-6, and procollagen-1 level, in the glottoplasty than control group. The histological findings showed that the lamina propria (LP) ratio (LP pixels/total vocal fold pixels) was not significantly different between the two groups. Based on the vocal fold vibration and real-time PCR results, the 532-nm diode laser improved vocal fold vibration in a rabbit model of vocal fold scarring.

A Novel Intervention That Prevents Vocal Fold Scarring

We evaluated the preventive efficacy of stromal vascular fraction (SVF) for vocal fold scar in a rabbit model. Animal model. The study included 40 male New Zealand white rabbits: 20 received vocal fold scar surgery served as normal controls (control group). The other 20 received the same vocal fold scar surgery with SVF injection (SVF group) Histological and high-speed video analyses of vocal fold vibration were performed 4 weeks after scar surgery and SVF injection. The maximum amplitude of vocal fold vibration was used to assess vocal fold vibration. A real-time PCR study was also performed to evaluate the scar regeneration and remodeling including TGF-ß1, IL-6, procollagen-1, MMP-2, 9, and HAS-2, 3. Vocal fold vibration analyses indicated that the maximum amplitude differences in the vibration of the SVF group were significantly higher than the control group. The histological findings showed that the collagen density ratio were significantly lower in the SVF group compared to the control group. Real-time Polymerase Chain Reaction (PCR) study showed significant increases of MMP-2, 9 and HAS-2, 3, and a decrease of TGF-ß1, IL-6, procollagen-1 in the SVF group compared to the control group. Based on the vocal fold vibration study, histological findings, and real-time PCR study, SVF injection showed preventive activity and improvement of vocal fold vibration for vocal fold scar in a rabbit model.

Contribution of laryngeal size to differences between male and female voice production.

In this study we investigated the effect of sex- and age-related differences in vocal fold length, thickness, and depth on voice production in a three-dimensional vocal fold model. The results showed that the cause-effect relationships between vocal fold physiology and voice production previously identified in an adult male-like vocal fold geometry remained qualitatively the same in vocal folds with geometry representative of adult females and children. We further showed that the often-observed differences in voice production between adult males, adult females, and children can be explained by differences in length and thickness. The lower F0, higher flow rate, larger vocal fold vibration amplitude, and higher sound pressure level (SPL) in adult males as compared to adult females and children can be explained by differences in vocal fold length. In contrast, the thickness effect dominated and contributed to the larger closed quotient of vocal fold vibration, larger normalized maximum flow declination rate, and lower H1-H2 in adult males as compared to adult females and children. The effect of differences in vocal fold depth was generally small. When targeting a specific SPL, adult males experienced a lower peak vocal fold contact pressure during phonation than adult females and children.

Effect of Subglottic Stenosis on Vocal Fold Vibration and Voice Production Using Fluid–Structure–Acoustics Interaction Simulation

An in-house 3D fluid–structure–acoustic interaction numerical solver was employed to investigate the effect of subglottic stenosis (SGS) on dynamics of glottal flow, vocal fold vibration and acoustics during voice production. The investigation focused on two SGS properties, including severity defined as the percentage of area reduction and location. The results show that SGS affects voice production only when its severity is beyond a threshold, which is at 75% for the glottal flow rate and acoustics, and at 90% for the vocal fold vibrations. Beyond the threshold, the flow rate, vocal fold vibration amplitude and vocal efficiency decrease rapidly with SGS severity, while the skewness quotient, vibration frequency, signal-to-noise ratio and vocal intensity decrease slightly, and the open quotient increases slightly. Changing the location of SGS shows no effect on the dynamics. Further analysis reveals that the effect of SGS on the dynamics is primarily due to its effect on the flow resistance in the entire airway, which is found to be related to the area ratio of glottis to SGS. Below the SGS severity of 75%, which corresponds to an area ratio of glottis to SGS of 0.1, changing the SGS severity only causes very small changes in the area ratio; therefore, its effect on the flow resistance and dynamics is very small. Beyond the SGS severity of 75%, increasing the SGS severity, leads to rapid increases of the area ratio, resulting in rapid changes in the flow resistance and dynamics.

Vocal Fold Reconstruction Using an Autologous Pedicled Fat Flap in a Rabbit Model.

We evaluated the efficacy of a vocal fold reconstruction technique using a vascularized autologous pedicled fat (PEFA) flap in a rabbit model of vocal fold paralysis. Animal model. The study included 30 male New Zealand White rabbits; 20 received vocal fold reconstructions (PEFA group) and 10 served as normal controls (control group). The right recurrent laryngeal nerve was resected, and simultaneous PEFA flap reconstruction was performed. The PEFA flap, including a pre-epiglottic fat and thyroid perichondrium, was elevated and implanted through a window at the inferior border of the thyroid cartilage. Histological and high-speed video analyses of vocal fold vibration were performed 1 month after PEFA reconstruction. The maximum amplitude of vocal fold vibration and the dynamic glottal gap were used to assess vocal fold vibration. The histological findings showed that the lamina propria ratio (lamina propria pixels/total vocal fold pixels) and the total number of vocal fold pixels were similar between the PEFA and control groups. Vocal fold vibration analyses indicated that the maximum amplitude differences in the vibration were slightly lower in the PEFA group. However, the dynamic glottal gap of the vocal fold was not significantly different between the PEFA group and the control group. The PEFA flap vocal fold reconstruction technique maintained the vocal fold area without a significant reduction in vocal fold vibration in a rabbit model. NA Laryngoscope, 130:1770-1774, 2020.

Fundamental Frequency in Excised Human Larynges after Anterior Glottic Web Formation of Various Extents.

To determine the effect of vocal fold anterior web formation on fundamental frequency with a cadaveric excised larynx model. Experimental study with excised human larynges. Academic tertiary care hospital. Sixteen freshly excised human larynges were evaluated with high-speed videoendoscopy and digital kymography during artificially produced vibration. Each larynx was assessed in 4 conditions: preoperative controls and after 25%, 33%, and 50% decreases in the vibratory portion of the vocal folds. The following parameters were evaluated: fundamental frequency, periodicity, vocal fold vibration amplitude, phase symmetry, and glottic closure. The mean fundamental frequencies were 208.87, 250.20, 292.37, and 342.67 Hz for preoperative controls and 25%, 33%, and 50% reductions in vibratory length of the vocal folds, respectively. Fundamental frequency increased with each increase in anterior glottic web extent, and the difference among the groups was statistically significant in absolute values in hertz and in semitone elevation. The mathematical models for estimating postoperative fundamental frequency had a statistically significant coefficient. The vibration of the vocal folds remained periodic in all larynges before and after the procedures. There was a significant and progressive increase in the fundamental frequency with each enlargement of anterior glottic web. Based on the control frequency, mathematical models could estimate the value of the fundamental frequency after the procedure.

Effect of Longitudinal Variation of Vocal Fold Inner Layer Thickness on Fluid-Structure Interaction During Voice Production.

A three-dimensional fluid-structure interaction computational model was used to investigate the effect of the longitudinal variation of vocal fold inner layer thickness on voice production. The computational model coupled a finite element method based continuum vocal fold model and a Navier-Stokes equation based incompressible flow model. Four vocal fold models, one with constant layer thickness and the others with different degrees of layer thickness variation in the longitudinal direction, were studied. It was found that the varied thickness resulted in up to 24% stiffness reduction at the middle and up to 47% stiffness increase near the anterior and posterior ends of the vocal fold; however, the average stiffness was not affected. The fluid-structure interaction simulations on the four models showed that the thickness variation did not affect vibration amplitude, glottal flow rate, and the waveform related parameters. However, it increased glottal angles at the middle of the vocal fold, suggesting that vocal fold vibration amplitude was determined by the average stiffness of the vocal fold, while the glottal angle was determined by the local stiffness. The models with longitudinal variation of layer thickness consumed less energy during the vibrations compared with the constant layer thickness one.

Severity of dysphonia in patients during first days after iatrogenic injury.

The most common cause of vocal fold paralysis (VFP) is iatrogenic injury. Patients with symptoms of VFP present to the specialist after a couple of weeks or even months since the onset of symptoms. In the literature, the data regarding speech impairment during the first days after a iatrogenic injury is lacking. to evaluate the quality of voice during first days of vocal fold paralysis following a iatrogenic injury. Twenty-five patients with iatrogenic vocal fold paralysis who presented for phoniatric consultation at the Department of Otolaryngology of the Medical University of Warsaw between May 2015 and December 2016 were enrolled in the study. The patients were examined 1-2 days since the onset of speech deterioration. In all patients, laryngeal videolaryngostroboscopy was performed, based on which the following were assessed: vocal fold mobility, mucosal wave, phonation closure, simultaneity and amplitude of vocal fold vibration. Acoustic analysis was performed, and the following acoustic parameters were evaluated: DSI, F0, Shimmer, Jitter, NHR. Also, the maximal phonation time of [a] sound (MPT a) was assessed and the voice perception analysis with the GRBAS scale was performed. The patients self-evaluated their voice using a 10-point VAS scale. Based on the videolaryngostroboscopy, phonatory insufficiency and asymmetrical vocal fold vibration were observed. On perception assessment with GRBAS scale, we noticed slight to mild degree hoarseness, breathiness of sound and weakened voice. In majority of patients, the maximal phonation time of [a] sound was significantly reduced. All patients showed abnormal acoustic parameters. None of them rated their voice as perfectly normal on VAS scale.

Impact of Cricothyroid Muscle Contraction on Vocal Fold Vibration: Experimental Study with High-Speed Videoendoscopy

The aim of this study was to evaluate the effects of cricothyroid muscle contraction on vocal fold vibration, as evaluated with high-speed videoendoscopy, and to identify one or more aspects of vocal fold vibration that could be used as an irrefutable indicator of unilateral cricothyroid muscle paralysis. This was an experimental study employing excised human larynges. Twenty freshly excised human larynges were evaluated during artificially produced vibration. Each larynx was assessed in three situations: bilateral cricothyroid muscle contraction, unilateral cricothyroid muscle contraction, and no contraction of either cricothyroid muscle. The following parameters were evaluated by high-speed videoendoscopy: fundamental frequency, periodicity, amplitude of vocal fold vibration, and phase symmetry between the vocal folds. Although neither unilateral nor bilateral cricothyroid muscle contraction altered the periodicity of vibration or the occurrence of phase asymmetry, there was a significant decrease in fundamental frequency in parallel with decreasing longitudinal tension. We also found an increase in vibration amplitude of right and left vocal folds, which were similar in terms of their behavior for this parameter in the various situations studied. Our results suggest that differences in vibration amplitude and phase symmetry between vocal folds are not reliable indicators of unilateral cricothyroid muscle paralysis.

A Preliminary Quantitative Comparison of Vibratory Amplitude Using Rigid and Flexible Stroboscopic Assessment

The purpose of this study was to establish preliminary, quantitative data on amplitude of vibration during stroboscopic assessment in healthy speakers with normal voice characteristics. Amplitude of vocal fold vibration is a core physiological parameter used in diagnosing voice disorders, yet quantitative data are lacking to guide the determination of what constitutes normal vibratory amplitude. Eleven participants were assessed during sustained vowel production using rigid and flexible endoscopy with stroboscopy. Still images were extracted from digital recordings of a sustained /i/ produced at a comfortable pitch and loudness, with F0 controlled so that levels were within ±15% of each participant's comfortable mean level as determined from connected speech. Glottal width (GW), true vocal fold (TVF) length, and TVF width were measured from still frames representing the maximum open phase of the vibratory cycle. To control for anatomic and magnification differences across participants, GW was normalized to TVF length. GW as a ratio of TVF width was also computed for comparison with prior studies. Mean values and standard deviations were computed for the normalized measures. Paired t tests showed no significant differences between rigid and flexible endoscopy methods. Interrater and intrarater reliability values for raw measurements were found to be high (0.89-0.99). These preliminary quantitative data may be helpful in determining normality or abnormality of vocal fold vibration. Results indicate that quantified amplitude of vibration is similar between endoscopic methods, a clinically relevant finding for individuals performing and interpreting stroboscopic assessments.

Reliability of laryngostroboscopic evaluation on lesion size and glottal configuration: A revisit

This study investigated the inter-rater and intrarater reliability of four basic visual perceptual parameters (lesion size rating and glottal configuration) in laryngostroboscopic evaluation. Cohort Study. Two hundred fifty-five laryngostroboscopic video samples were evaluated by three raters on four measurements: 1) mass lesion size rating, 2) amplitude of vocal fold vibration, 3) supraglottic activity, and 4) shape of the glottal closure using the modified Stroboscopy Examination Rating Form. Good inter- and intrarater reliability were found in rating the lesion size (0.75-0.81, P=.001), anteroposterior supraglottic activity (0.64, P=.001), and glottal closure (0.65, P=.001). Inter-rater reliability in evaluating the mediolateral supraglottic activity and the amplitude of vocal fold vibration were low to moderate (0.50 and 0.46, respectively, P=.001), whereas the intrarater reliability was more variable (0.2-0.70). The findings indicated that the evaluation of static structures like lesion size rating, the anteroposterior supraglottic compression, and the glottal closure is a relatively reliable method. The evaluation of dynamic structures, such as the vocal fold vibratory amplitude measure was, however, found to be of low reliability. NA.

Vocal fold vibration amplitude, open quotient, speed quotient and their variability along glottal length: Kymographic data from normal subjects

Quantitative knowledge about healthy vocal fold vibration characteristics provides the basis for an objective assessment of vocal fold vibrations. In this study, using high-speed videolaryngoscopy the alterations of the relative vibration amplitudes, open quotients, and speed quotients were analyzed along the glottal length in 30 male and 30 female healthy subjects. The maximum vibration amplitude was identified at 41.1% ± 10.8% and 46.5% ± 18.0% of the visible glottal length in females and males, respectively. The average open quotients decreased in females and males from posterior to anterior, while the speed quotients did not change systematically. The reported normative values can be used to distinguish normal and abnormal vibrations in clinical practice when aiming at quantitative diagnosis of functional voice disorders.

Hyperplastic epithelial lesions of the vocal folds: combined use of exfoliative cytology and laryngostroboscopy in differential diagnosis

The mainstay of successful tumor therapy is early detection of neoplastic tissue. Although exfoliative cytology has proven to be a reliable tool, its importance is still underestimated. Laryngostroboscopy is the most important tool for functional investigation in laryngological and phoniatric diagnosis. Stroboscopic evaluation allows early detection of infiltrative processes of the vocal folds. Aim of our study was to demonstrate that combination of both, exfoliative cytology and stroboscopy, provides a highly sensitive and easy to perform method in differential diagnosis of epithelial hyperplastic lesions of the vocal folds. In 130 patients with varying degrees of vocal fold keratosis up to glottic cancer, preoperative layngostroboscopy was performed. Stroboscopy was classified pathological in case of reduced or abolished amplitude of vocal fold vibration and/or reduced or abolished mucosal wave propagation. Under general anaesthesia histology with corresponding cytological specimens were obtained. The latter were classified in three groups reaching from normal (I), dysplastic (II), up to malignant (III) cytology. Invasive carcinoma was diagnosed in 32 cases by histology, corresponding malignant cytology was found in 21 specimens (sensitivity: 74%). By certain combination of cytology with pathological stroboscopy, a sensitivity of more than 97% can be achieved. Combination of cytology and stroboscopy allows detection of glottic cancer with a sensitivity of 97%, in contrast to 74% as found by cytology alone. This combination can be used as preliminary or sorting procedure and gives the opportunity of early detection, as well as for follow-up examinations. For repeated biopsies can cause scars with consecutive voice impairment, this procedure is very smooth but nevertheless reliable method.

Autologous grafts for treatment of vocal sulcus and atrophy

To obtain complete glottal closure, and evaluate improvement of vocal fold vibration amplitude and vocal quality in patients with sulcus vocalis. Autogenous fat and/or fascia augmentation was used in 34 patients with sulcus vocalis. Mean follow-up time was 1 year. The perceptual acoustic and phonatory functions and videolaryngostroboscopic data were evaluated before and after the procedure. Most of the individuals reported an improvement of vocal quality, a complete glottal closure, an enhancement of mucosal wave excursion, and significant results of acoustic perceptual and phonatory functions after the surgery. Fat and fascia injections are effective autogenous implants and should be considered options in the treatment of patients with sulcus vocalis and vocal fold atrophy.

Using the Relaxation Oscillations Principle for Simple Phonation Modeling

Well-known multimass models of vocal folds are useful to describe main behavior observed in human voicing but their principle of functioning, based on harmonic oscillation, may appear complex. This work is designed to show that a simple one-mass model ruled by laws of relaxation oscillation can also depict main behavior of glottis dynamic. Theory of relaxation oscillation is detailed. A relaxation oscillation model is assessed through a numerical simulation using conventional values for tissue characteristics and subglottal pressure. As expected, raising the mass decreases the fundamental frequency and increases the amplitude of vocal fold vibration: for a mass ranging from 0.01 to 0.4 g, F0 decreased from 297.5 to 42.5 Hz and vibrational amplitude increased from 1.26 to 3.25 mm (for stiffness k=10Nm(-1), damping r=0.015 N s m(-1), and subglottal pressure=1 kPa). Stiffness value has the opposite effect. The subglottal pressure controls the fundamental frequency with a rate ranging from 20 to 50 Hz/kPa. The vibrational amplitude is also controlled linearly by subglottal pressure from 0.22 to 0.26 mm/kPa. The range of phonation threshold pressure (PTP) is close to the values currently proposed, that is, 0.1 to 1 kPa and varies with the fundamental frequency. The relaxation oscillator is a simple and useful tool for modeling vocal fold vibration.

Clearing microvascular lesions of the true vocal fold with the KTP/532 laser.

Although used for treating vascular malformations, KTP (532 nm) lasers have not been used to treat microvascular lesions of the vocal fold. The efficiency of KTP laser operation in the continuous mode with a 0.4- or 0.6-mm beam (1- to 2-W aim for 3 to 7 seconds delivering a total energy of 3 to 7 J) was studied retrospectively in patients with microvascular lesions of the vocal fold (n = 14). The perceptual acoustic, phonatory function, and videolaryngostroboscopic data were evaluated before and after operation in 10 patients. At follow-up (mean, 7 months), the results were excellent in all patients. Their phonatory function (jitter, shimmer, grade, breathiness, and roughness) significantly improved (p < .01). The videolaryngostroboscopic rating showed significant improvement in the amplitude of vocal fold vibration and excursion of the mucosal wave (p < .05). No postoperative recurrence or complications were noted. The KTP laser operation is a useful, cost-effective, and time-saving procedure and can be considered as an option in management of patients with microvascular lesions of the vocal fold, particularly those with repeated hemorrhages. Because the operation is easy (compared to other surgical methods) and has no major side effects, the prospect of total patient recovery is excellent.

Fat Augmentation for Nonparalytic Glottic Insufficiency

While autogenous fat augmentation for glottic insufficiency has been used before, relatively little information is currently available on the effectiveness of fat injection in patients with nonparalytic glottic insufficiency resulting from problems such as various defects of vocal atrophy or sulcus vocalis. This paper compares retrospectively the efficiency of fat injection after surgery in patients with vocal atrophy (n = 16) and sulcus vocalis (n = 8). The perceptual acoustic and phonatory functions and videolaryngostroboscopic data were evaluated before and after fat augmentation in 24 patients. The mean follow-up time was 19.5 months. Fifteen patients displayed excellent results; 1 showed some improvement; 6 experienced postprocedure failure, and 2 were not available for follow-up analysis. Perceptual rating showed significant improvement in grade, roughness and breathiness (p < 0.05). The videolaryngostroboscopic rating showed significant improvements in vocal fold edge linearity, vocal fold vibration amplitude and mucosal wave excursion (p < 0.05). More improvement in vocal atrophy was observed compared with sulcus vocalis following fat injection procedures. Our research showed that middle defects improved more compared to those in the anterior and posterior area. Fat injection is an effective autogenous implant and may be considered as an option in the treatment of patients with vocal atrophy or sulcus vocalis. Although fat reabsorption was a problem, repeating the procedure could be considered.

Fat Augmentation following Microsurgical Removal of the Vocal Nodules: Long-Term Results

While the effectiveness of autogenous fat augmentation after microsurgical removal (FAMSR) of the vocal nodules (VN) has been previously shown in patient treatment programs, relatively little information is available regarding the long-term effectiveness of such a procedure. This paper examines, in retrospect, the long-term effectiveness of FAMSR in patients with VN (n = 41) using pre- and post-FAMSR perceptual acoustic and phonatory function data and videolaryngostroboscopic findings for 33 patients. The mean follow-up time was 18 months. Thirty-three (80.4%) patients displayed excellent results; 4 (9.8%) experienced improvement, and 4 (9.8%) postprocedure failure. Patient phonatory functions showed significant improvements in shimmer, harmonic-to-noise ratio, phonation time (p < 0.05), grade, roughness and breathiness (p < 0.001). The videolaryngostroboscopic rating showed significant improvements in vocal fold edge linearity, vocal fold vibration amplitude, and mucosal wave excursion (p < 0.001). Improvements observed through long-term follow-up tended to be less dramatic in patients with recurrent VN than those with nonrecurrent VN. FAMSR is an easy, safe, and fast procedure which should be considered as an option in treating VN patients who either require surgery or do not have the time or perseverance to complete a lengthy program of speech therapy.

Effects of a Vocally Fatiguing Task and Systemic Hydration on Men's Voices

Summary: Voice disorders, specifically vocal fatigue, are more commonly reported by women than by men. Previously, 4 women with normal untrained voices read loudly for 2 hours in an attempt to fatigue the voice. Vocal function deteriorated, as indicated by increases in phonation threshold pressure (PTP) and self-perceived phonatory effort. The increase in PTP was delayed or attenuated to some degree in 3 of the women when they drank ample amounts of water before the experiment. The current study examined the same vocal-loading task and water-drinking condition in 4 vocally normal men. PTP increased after the loud-reading task. Although 2 of the men appeared to benefit from increased systemic hydration (PTP increased more when they were underhydrated than well-hydrated), the other 2 men's data changed in the opposite direction. Phonatory effort correlated well with PTP; this varied across subject and pitch. Laryngeal endoscopy revealed an anterior glottal gap in two men after the loud-reading task. Amplitude of vocal fold vibration was judged to be reduced after the loud-reading task in three subjects when underhydrated and one subject when well hydrated. The high between-subject variability prohibits a conclusion that drinking water is beneficial to vocal function in men, but all subjects studied to date demonstrated detrimental vocal effects of prolonged loud talking.

Stroboscopic assessment of vocal fold keratosis and glottic cancer.

Disruption of the normal viscoelastic properties of the superficial lamina propria (SLP) results in aberrant vocal fold vibration and mucosal wave propagation. Therefore, an investigation was performed to determine whether stroboscopy is a reliable method for 1) differentiating invasive glottic carcinoma from intraepithelial atypia or 2) determining the depth of cancer invasion. An analysis was done on the preoperative vocal fold vibration characteristics of 62 keratotic (intraepithelial, 45; cancer, 17) lesions that were subsequently resected by means of microlaryngoscopy. Histopathology and intraoperative mapping were used to specify the depth of invasion. A panel of 4 blinded judges was used to assess the amplitude of vocal fold vibration and the magnitude of mucosal wave activity in the region of the lesion from videostroboscopic recordings. The final comparative data set comprised only those ratings that achieved at least 75% interjudge agreement. Of the 28 intraepithelial lesions that could be reliably evaluated for amplitude of vocal fold vibration, only 2 were normal, with the amplitude reduced in 24 and absent in 2. Of the 30 intraepithelial lesions in which mucosal wave activity could be reliably assessed, only 2 were normal, with the wave reduced in 24 and absent in 4. Furthermore, amplitude of vocal fold vibration and magnitude of mucosal wave propagation were absent in 2 of 4 carcinomas in which the depth of microinvasion did not reach the vocal ligament. According to the findings herein, reduced amplitude of vocal fold vibration and/or mucosal wave propagation associated with keratosis did not reliably predict the presence of cancer or the depth of cancer invasion into the laminae propriae. However, the presence of a flexible mucosal wave probably indicates that there is not extensive vocal ligament invasion. Reductions in the amplitude of vocal fold vibration and in mucosal wave magnitude were usually noted in intraepithelial atypia, despite the fact that there was no invasion into the SLP. The reduced epithelial pliability could be due to bulky keratosis and/or alteration of the SLP occurring as a result of inflammation or fibrovascular scarring.