Laryngeal aerodynamics associated with selected voice disorders

Measures of estimated subglottal air pressure and laryngeal air flow during speech production are compared for adults with normal laryngeal function and those with laryngeal abnormalities. The most traditional measure, air flow during sustained vowel production, is not a strong predictor of laryngeal function during speech production. Subglottal air pressure and laryngeal air flow offer insight into voice disorders and provide directions for therapy as well as a method for the quantitative assessment of treatment outcomes.     

Laryngeal/voice findings in patients with velopharyngeal dysfunction

It is reported frequently that individuals with palatal clefts have a high occurrence of laryngeal/voice symptoms. It has been speculated that vocal pathology in this population is the result of laryngeal compensation for abnormal velopharyngeal valving. This paper describes the prevalence of laryngeal/voice findings in a group of 85 patients referred for multimethod evaluation of velopharyngeal dysfunction. Forty-one percent of the patients had auditorily perceived voice symptoms and/or observable laryngeal abnormalities. Twenty-one percent of the patients had vocal fold nodules or thickened vocal folds. There was no clear relationship between laryngeal/voice findings and nasoendoscopic or aerodynamic assessments of velopharyngeal dysfunction. However, there was a significant relationship between laryngeal/voice findings and estimated subglottal pressure. Patients with laryngeal/voice findings (with or without nodules) had average estimated subglottal pressure values which were outside the normal range more often than patients without laryngeal/voice findings. These results suggest patients referred for assessment of velopharyngeal dysfunction should receive a comprehensive evaluation which includes screening laryngeal structure and function.     

Onset and offset phonation threshold flow in excised canine larynges

Objectives/Hypothesis: In this study, we examined the hypothesis that the minimum flow required for phonation onset, the onset phonation threshold flow (PTF), is greater than the minimum flow to sustain phonation, the offset PTF. We also explored the hypothesis that the ratio of these two (PTF offset divided by PTF onset) falls within [0.707, 1.0]. Study Design: This was a methodology study to measure onset and offset PTFs in 10 excised canine larynges; their ratio (PTF offset divided by PTF onset) was predicted to fall in a specific domain. Methods: The onset and offset PTF and phonation threshold pressure (PTP) values were observed using 10 excised canine larynges mounted on a bench apparatus. The subglottal flow was increased until phonation was observed, and then decreased until phonation ceased; airflow and pressure measurements at critical conditions of phonation were observed as the PTF and PTP. Larynges with elongated vocal folds were then tested to observe PTF and determine if the hypothesis was observed in pathologic‐like larynges. Results: The offset PTF was always less than the onset PTF (P ? .0001) and 80.0% of the observed onset‐offset PTF ratios were bound by [0.707, 1.0]. Conclusions: PTF onset or offset could be a useful diagnostic parameter of the voice, particularly when used in conjunction with PTP to describe laryngeal resistance and aerodynamic power. Further exploration of the relationship between onset and offset PTF values could augment clinical diagnostic ability and advance current theories on the physics of phonation.     

Comparison of voice characteristics following three different methods of treatment for laryngeal cancer

INTRODUCTION: Laryngeal cancer treatment has become more complex and diversified in past decades. Many different methods of treatment have evolved, and most have been able to restore the patient's function and maintain some form of functional speech. This study was designed to evaluate the voice and speech characteristics of patients who have undergone different treatments for laryngeal cancer and to compare those characteristics with those of age- and sex-matched normal laryngeal speakers. METHODS: Twenty-two male subjects participated in the study. Five men were treated with radiation therapy, 6 men had supracricoid partial laryngectomy, 6 men had undergone total laryngectomy with tracheoesophageal puncture, and 5 men were normal laryngeal speakers. Acoustic, aeromechanical, and perceptual assessments of speech were collected. RESULTS: Significant age effects were found for maximum phonation times. As age increased, maximum phonation time decreased (p < .005). Significant differences were found between groups for the following dependent variables: percentage of voiceless phonation, maximum phonation time, laryngeal airway resistance, subglottal pressure, oral flow, and word intelligibility. Trends in the data for differences between groups were noted for the following acoustic variables: noise-to-harmonics ratio, jitter, and shimmer. CONCLUSIONS: All patients developed or maintained a source of voicing after treatment and could use speech functionally, as demonstrated by normal sentence intelligibility. The radiation treatment group had voices that differed the least from the control group, whereas the opposite was true for the surgical groups, especially for those with total laryngectomy.     

Collagen injection as a supplement to arytenoid adduction for vocal fold paralysis

OBJECTIVES: Dysphonia associated with vocal fold paralysis can persist even after successful medialization procedures, including arytenoid adduction. It is hypothesized that laryngeal collagen injection could improve phonation following arytenoid adduction in selected patients. Our objective was to evaluate how collagen injection could result in measurable improvements in vocal function and voice quality. METHODS: Forty patients with unilateral vocal fold paralysis who had undergone arytenoid adduction underwent transoral injection of non-cross-linked bovine dermal collagen by means of indirect laryngoscopy and a curved injection device. A control group of 40 patients underwent arytenoid adduction but not collagen injection. The patients' voice quality was assessed perceptually with the GRBAS scale, and vocal function was assessed by acoustic and aerodynamic measures (maximum phonation time and transglottal DC flow). The relative glottal area was also assessed by videostroboscopy. RESULTS: Significant improvements in vocal function and voice quality were observed with collagen injection for those patients who did not achieve satisfactory glottal competence with arytenoid adduction alone. Glottal area measurements revealed that glottic insufficiency was significantly reduced after arytenoid adduction as well as after collagen injection. CONCLUSIONS: The findings suggest that collagen injection could be an effective supplementary treatment for improving voice following arytenoid adduction. It has the advantage of being a minimally invasive outpatient office procedure. The long-term efficacy of the procedure should be explored.     

Functional outcomes following nonsurgical treatment for advanced-stage laryngeal carcinoma

OBJECTIVES: Objectives were 1) to provide comprehensive evaluations of functional outcomes using perceptual and objective measures of patients treated nonsurgically for stages III and IV laryngeal squamous cell carcinoma and 2) to propose a standard battery of tests that can be used for appraising functional outcomes in this patient population. STUDY DESIGN: Retrospective study of 14 patients. METHODS: Perceptual measures of voice were obtained using blinded expert listener impression ratings and a validated quality of life questionnaire (Voice Handicap Index). Objective data included acoustic, speech aerodynamic, and videostroboscopic evaluations. Patients were also assessed relative to stability of the airway, secretion control, and ability to tolerate oral diet without aspiration symptoms. RESULTS: Patients demonstrated functional but abnormal voice, speech, and swallowing abilities after treatment. More specifically, patients were judged to have moderately deviant biomechanical findings on videostroboscopy that did not improve with longer time intervals after treatment. These findings helped to explain the moderately abnormal acoustic and aerodynamic measurements revealing high values for jitter, shimmer, noise, airflow, glottal resistance, and subglottal pressures and substantially lower than normal maximum phonation times. Expert listeners were in agreement with the objective findings. However, patients rated themselves as only mildly impaired with regard to the emotional, physical, and functional handicapping effects of treatment, difficulties that were judged to improve with longer time intervals after treatment. Swallowing function showed a trend toward improvement for patients with time intervals of more than 12 months since completion of therapy. CONCLUSIONS: Patients demonstrated variable degrees of laryngeal dysfunction as evidenced by perceptual and objective measures. Patients rated themselves to be only mildly handicapped with regard to voice quality. A methodology and battery of tests are proposed to help standardize outcome data collection for this patient population.     

Quantitative measures of laryngeal function following teflon® injection or thyroplasty type I

Laryngeal/voice function was evaluated in six patients with unilateral true vocal fold paralysis following treatment with Teflon® injection (TEF) compared to six patients treated with thyroplasty type I (THY). Auditory perceptual, aerodynamic, and endoscopic assessments were conducted. Three judges rated nine voice characteristics. Aerodynamic measures included estimated subglottal pressure, airflow, and laryngeal resistance. Two judges rated laryngeal characteristics from flexible fiberoptic assessment. The THY group had significantly better voice quality and better quantitative aerodynamic findings compared to the TEF group. The TEF group also was more likely to have an irregular vocal fold edge, an irregular glottal closure pattern, a higher occurrence of hyperfunction and hypertrophy of the false vocal folds, edema, and erythema of the paralyzed folds. Results suggest that THY was associated with more favorable measures of laryngeal/voice function than TEF. It is likely that the poorer perceptual, aerodynamic, and endoscopic findings associated with TEF injection may be due to violation of the true vocal fold cover, particularly increased true vocal fold mass and stiffness.     

A new instrument for intraoperative assessment of individual vocal folds

OBJECTIVES: Intraoperative assessment of vocal fold vibration during phonomicrosurgery performed under general anesthesia may enhance surgical decision-making. We therefore developed and bench-tested a new device we refer to as the aerodynamic vocal fold driver (AVFD). MATERIALS AND METHODS: The AVFD comprises a hand-held probe that uses airflow to drive individual vocal folds into phonatory-like vibration. This permits stroboscopic visualization of mucosal waves with simultaneous control of subglottal air pressure. In initial experiments to validate the technique, AVFD driven phonation and conventional whole-larynx phonation were compared using excised canine larynges (n = 14). RESULTS: Single vocal fold phonation using the AVFD and whole larynx phonation yielded similar, positive correlations between subglottal pressure and both amplitude and frequency of vibration. Experiments simulating vocal fold scar-related mucosal stiffening by subepithelial injection of fixative showed the expected elevation of phonation threshold pressures as measured with the AVFD. Likewise, unilateral tissue compression injury disrupted vocal fold vibration, and the AVFD was useful for quantifying improvement in the damaged vocal fold after repair with injection of cross-linked hyaluronic acid gel. CONCLUSIONS: These results show that this new instrument has the potential to provide novel and useful information for laryngeal experimentation and to improve phonosurgery.     

Results of videostroboscopic examinations of vocally healthy candidates for voice intensive professions

BACKGROUND: Questions regarding the vocal aptitude for voice professions are common in the daily phoniatrical and otorhinolaryngological practice. According to the classification by Koufman, Isaccson and Stemple professions can be classified into four groups. While it is common to perform laryngeal investigations and analyses of the vocal efficacy for candidates of elite vocal performers (level 1), i. e. singers and actors, those examinations are usually not executed for voice and speaking intensive professions (level 2) like teachers, as there is no legal base. This group is, however, predisposed with regard to professional voice disorders. METHODS: Aim of the study was therefore to determine the frequency of laryngeal findings in a group of previously asymptomatic subjects using videostroboscopic examinations and to assess the risk concerning the emergence of professional voice disorders. 545 candidates for voice intensive professions have been examined with regard to the existence of any organic or secondary organic alterations on the vocal folds. RESULTS: One third of the subjects showed benign laryngeal alterations, which were not consequentially associated with auditive alterations of the voice sound and/or a consciousness of a voice disorder. Apart from 33 organic laryngeal alterations 129 phonation associated alterations of the vocal fold were determined. CONCLUSIONS: These subjects should especially in cases of excessive vocal demand and additional the efficacy reducing factors be regarded as a high risk group with regard to the emergence of professional voice disorders. The results underline the necessity to require vocal examinations and vocal assessment analyses for candidates of voice intensive professions in order to avoid professional voice disorders.     

Rabbit model with vocal fold hyperadduction

ObjectiveAdductor spasmodic dysphonia (AdSD) is caused by hyperadduction of the vocal folds during phonation, resulting in a strained voice. Animal models are not yet used to elucidate this intractable disease because AdSD has a difficult pathology without a definitive origin. For the first step, we established an animal model with vocal fold hyperadduction and evaluated its validity by assessing laryngeal function.MethodsIn this experimental animal study, three adult Japanese 20-week-old rabbits were used. The models were created using a combination of cricothyroid approximation, forced airflow, and electrical stimulation of the recurrent laryngeal nerves (RLNs). Cricothyroid approximation was added to produce a glottal slit. Thereafter, both RLNs were electrically stimulated to induce vocal fold hyperadduction. Finally, the left RLN was transected to relieve hyperadduction. The sound, endoscopic images, and subglottal pressure were recorded, and acoustic analysis was performed.ResultsSubglottal pressure increased significantly, and the strained sound was produced after the electrical stimulation of the RLNs. After transecting the left RLN, the subglottal pressure decreased significantly, and the strained sound decreased. Acoustic analysis revealed an elevation of the standard deviation of F0 (SDF0) and degree of voice breaks (DVB) through stimulation of the RLNs, and degradation of SDF0 and DVB through RLN transection. Formant bands in the sound spectrogram were interrupted by the stimulation and appeared again after the RLN section.ConclusionThis study developed a rabbit model with vocal fold hyperadduction . The subglottal pressure and acoustic analysis of this model resembled the characteristics of patients with AdSD. This model could be helpful to elucidate the pathology of the larynx caused by hyperadduction, and evaluate and compare the treatments for strained phonation.     

Respiratory and laryngeal function during spontaneous speaking in teachers with voice disorders.

PURPOSE: To determine if respiratory and laryngeal function during spontaneous speaking were different for teachers with voice disorders compared with teachers without voice problems. METHOD: Eighteen teachers, 9 with and 9 without voice disorders, were included in this study. Respiratory function was measured with magnetometry, and laryngeal function was measured with electroglottography during 3 spontaneous speaking tasks: a simulated teaching task at a typical loudness level, a simulated teaching task at an increased loudness level, and a conversational speaking task. Electroglottography measures were also obtained for 3 structured speaking tasks: a paragraph reading task, a sustained vowel, and a maximum phonation time vowel. RESULTS: Teachers with voice disorders started and ended their breath groups at significantly smaller lung volumes than teachers without voice problems during teaching-related speaking tasks; however, there were no between-group differences in laryngeal measures. Task-related differences were found on several respiratory measures and on one laryngeal measure. CONCLUSIONS: These findings suggest that teachers with voice disorders used different speech breathing strategies than teachers without voice problems. Implications for clinical management of teachers with voice disorders are discussed.     

Voice therapy for vocal fold paralysis

There is no doubt that vocal fold paralysis is a debilitating condition affecting an individual's general health and quality of life. Optimal management of a patient with vocal fold dysfunction by an otolaryngologist, speech scientist, and speech language pathologist results in detailed objective videostroboscopic evaluation of glottal configuration during phonation, acoustic and aerodynamic measures, laryngeal EMG (if appropriate), and the patient's self-rating of vocal disability. Profound glottal incompetence is typically managed surgically with a few voice therapy sessions after surgery to ensure optimal vocal function. Patients with more adequate glottal closure are often seen for voice therapy and lost to follow-up when their voices improve enough to satisfy their vocal needs. It is essential that a complete battery of assessments, including perceptual, aerodynamic, acoustic, and stroboscopic measures, be obtained at periodic intervals in surgical and nonsurgical patients so as to evaluate vocal function over time. One of the few rigorous studies of perceptual, acoustic, aerodynamic, and videofiberscopic findings in patients after medialization with fat and thyroplasty assessed patients before surgery and at short (1-3 months),middle (4-6 months), and long (7-12 months) intervals after surgery. Improvement in most parameters at short- and long-term intervals was noted but not in the middle interval. The best results were obtained in women. Continued difficulty in increasing and maintaining subglottal pressure for high-intensity phonation was observed in both male and female patients. This fine study raises a number of questions as follows. What objective phonatory measures should be assessed before and after intervention and at what time intervals? Why were the women's results better than the men's results when no correlation of age, pulmonary function, or severity of preoperative voice and aerodynamic impairment was observed? Should voice therapy be initiated at the 4- to 6-month interval when voice quality diminished or within 1 to 2 months after surgery so that the decrement in vocal function might not occur? Why did vocal function ultimately improve after 7 to 12 months? Heuer et al and Colton and Casper found similar outcome satisfaction in patients electing surgery compared with those that were seen for voice therapy; however, the patients with lesser glottal incompetence in both studies opted for therapy. Can we better define vocal parameters that help to predict which patients may need surgery rather than therapy? Should all patients with high airflow measures but near-normal subglottal pressures and MPT greater than 10 seconds undergo 6 weeks of voice therapy rather than medical intervention? If all surgical patients were seen for 6 weeks of postoperative therapy, would voice satisfaction ratings increase to greater than 70%? Can we perceptively or objectively differentiate patients whose postoperative voices will be excellent from those whose voices will be merely adequate? These questions can only be answered by the development and implementation of a rigorous protocol studying women and men of varying ages with unilateral vocal fold paralysis choosing medialization surgery and electing voice therapy. Standardized assessments must include perceptual,aerodynamic, acoustic, stroboscopic, and patient satisfaction measures during soft- and loud-intensity tasks before and at periodic intervals after the two interventions.     

Diagnosis of functional voice disorders by using the high speed recording technics

INTRODUCTION: Malfunctions of the human voice with unknown causes are denoted by "functional voice disorders". The high speed video imaging technique (HVT) allows the recording of the oscillating vocal folds in real time. A new method is presented, describing different types of oscillation and their onset mathematically. A precise classification of the kind of functional voice disorders is possible. METHODS: For 71 young women, from the HVT recordings two parameters were mathematically estimated, reflecting the phonation onset dynamics: The threshold value A(th), corresponding with the myoelastic tone of the vocal folds and a maximum sound pressure level of speech L(max), characterising the efficiency of voice. RESULTS: Both values are sensitive for functional voice disorders and enable a differentiation between these pathologies. DISCUSSION: Significant differences of the computed parameters between the pathological groups and normal voices substantiate the presented method as a stable and objective tool for medical diagnosis.     

Receiver operating characteristic analysis of aerodynamic parameters obtained by airflow interruption: a preliminary report

Aerodynamic parameters provide objective and quantitative measures of laryngeal functional status. Jiang et al previously introduced an airflow interruption technique that can determine mean phonatory airflow, subglottic pressure, and phonation threshold pressure simultaneously and noninvasively. In this study, we performed receiver operating characteristic (ROC) analysis to evaluate this airflow interruption apparatus for voice profile analysis in subjects with laryngeal polyps or nodules or with Parkinson's disease. Patients with polyps (n = 14), nodules (n = 9), and Parkinson's disease (n = 12) were evaluated with the airflow interruption apparatus. Normal subjects served as controls. Mean airflow, subglottic pressure, and phonation threshold pressure were determined. Discriminant analysis was used to create linear equations combining all three parameters in order to obtain a new combined parameter. Solutions to the linear equations yielded values for the combined parameter that took into account mean airflow, subglottic pressure, and phonation threshold pressure. Combined parameter values were used as data to generate ROC curves. Laryngeal polyps were distinguished from the normal larynx with a sensitivity of 0.929 and a specificity of 0.933 at the point of maximal efficiency. The area under the ROC curve was 0.977 (Az). Patients with Parkinson's disease were distinguished from normal subjects with a sensitivity of 0.667 and a specificity of 0.909 at the point of maximal efficiency. The area under the ROC curve was 0.7958 (Az). Nodules were able to be distinguished from normal with a sensitivity of 0.889 and a specificity of 1.00. The area under the ROC curve was 0.9565 (Az). Our conclusions are twofold. First, aerodynamic parameters may be combined for simultaneous consideration by the construction of linear equations by means of discriminant analysis. Second, the airflow interruption apparatus, when used for voice function evaluation, has high sensitivity and specificity.     

Laryngeal factors in voiceless consonant production in men, women, and 5-year-olds.

Voicing control in stop consonants has often been measured by means of voice onset time (VOT) and discussed in terms of interarticulator timing. However, control of voicing also involves details of laryngeal setting and management of sub- and supraglottal pressure levels, and many of these factors are known to undergo developmental change. Mechanical and aerodynamic conditions at the glottis may therefore vary considerably in normal populations as functions of age and/or sex. The current study collected oral airflow, intraoral pressure, and acoustic signals from normal English-speaking adults and children producing stop consonants and /h/ embedded in a short carrier utterance. Measures were made of stop VOTs, /h/ voicing and flow characteristics, and subglottal pressure during /p/ closures. Clear age and gender effects were observed for /h/: Fully voiced /h/ was most common in men, and /h/ voicing and flow data showed the highest variability among the 5-year-olds. For individual participants, distributional measures of VOT in /p t/ were correlated with distributional measures of voicing in /h/. The data indicate that one cannot assume comparable laryngeal conditions across speaker groups. This, in turn, implies that VOT acquisition in children cannot be interpreted purely in terms of developing interarticulator timing control, but must also reflect growing mastery over voicing itself. Further, differences in laryngeal structure and aerodynamic quantities may require men and women to adopt somewhat different strategies for achieving distinctive consonantal voicing contrasts.     

Non-organic dysphonia. II. A comparison of subglottal pressures in normal and pathological voices

In previous investigations, typical phonetogram differences have been revealed between healthy and pathological voices: the average maximum and minimum sound pressure levels that a patient suffering from non-organic dysphonia can produce at different fundamental frequencies deviate significantly from the corresponding values for a healthy voice. The subglottal pressure, being the primary tool for regulating the sound pressure level of voice, was estimated from the oral pressure during the voiceless stop/p/in 10 female and 10 male subjects with normal voices and in 10 female and 10 male non-organic dysphonic patients. In loud phonation, the female patients had significantly lower values than the female healthy subjects, while no corresponding significant difference was seen between the male subjects. In soft phonation, the male patients had significantly higher values than the normal healthy subjects, while the females showed no significant difference.     

A quantitative study of the medial surface dynamics of an in vivo canine vocal fold during phonation

OBJECTIVES/HYPOTHESIS: The purpose of this study was to measure the medial surface dynamics of a canine vocal fold during phonation. In particular, displacements, velocities, accelerations, and relative phase velocities of vocal fold fleshpoints were reported across the entire medial surface. Although the medial surface dynamics have a profound influence on voice production, such data are rare because of the inaccessibility of the vocal folds. STUDY DESIGN: Medial surface dynamics were investigated during both normal and fry-like phonation as a function of innervation to the recurrent laryngeal nerve for conditions of constant glottal airflow. METHODS: An in vivo canine model was used. The larynx was dissected similar to methods described in previous excised hemilarynx experiments. Phonation was induced with artificial airflow and innervation to the recurrent laryngeal nerve. The recordings were obtained using a high-speed digital imaging system. Three dimensional coordinates were computed for fleshpoints along the entire medial surface. The trajectories of the fleshpoints were preprocessed using the method of Empirical Eigenfunctions. RESULTS: Although considerable variability existed within the data, in general, the medial-lateral displacements and vertical displacements of the vocal fold fleshpoints were large compared with anterior-posterior displacements. For both normal and fry-like phonation, the largest displacements and velocities were concentrated in the upper medial portion. During normal phonation, the mucosal wave propagated primarily in a vertical direction. Above a certain threshold of subglottal pressure (or stimulation to the recurrent laryngeal nerve), an abrupt transition from chest-like to fry-like phonation was observed. CONCLUSIONS: The study reports unique, quantitative data regarding the medial surface dynamics of an in vivo canine vocal fold during phonation, capturing both chest-like and fry-like vibration patterns. These data quantify a complex set of dynamics. The mathematical modeling of such complexity is still in its infancy and requires quantitative data of this nature for development, validation, and testing.     

Vocal efficiency measurements in subjects with vocal polyps and nodules: a preliminary report

Vocal efficiency is a quantitative measure of the ability of the larynx to convert subglottal power to acoustic power. On the basis of the scant previous literature and clinical intuition, we tested the hypothesis that vocal efficiency, as an indicator of the functional status of the larynx, is abnormally reduced in persons with vocal nodules and polyps. Because the most difficult aspect of obtaining measures of vocal efficiency has been the determination of subglottal pressure, we applied a noninvasive airflow interruption technique for this purpose. Subjects with normal voices (n = 22), vocal polyps (n = 14), and vocal nodules (n = 16) phonated at different intensities into a mask connected by way of piping to a flow meter, a pressure transducer, and an acoustic microphone. Inflation of a balloon-type valve located within the piping provided interruption of phonation. The intraoral pressure plateau occurring during flow interruption was used to estimate subglottal pressure. Subglottal power and acoustic power were determined, and their quotient provided a measure of vocal efficiency. The vocal efficiency in the normal subjects averaged 1.15 x 10(-5) at 70 dB, 3.17 x 10(-5) at 75 dB, 7.52 x 10(-5) at 80 dB, and 1.41 x 10(-4) at 85 dB. The vocal efficiency in the patients with vocal polyps averaged 3.62 x 10(-6) at 70 dB, 8.34 x 10(-6) at 75 dB, 2.10 x 10(-5) at 80 dB, and 4.26 x 10(-5) at 85 dB. The vocal efficiency in the patients with vocal nodules averaged 4.32 x 10(-6) at 70 dB, 1.57 x 10(-5) at 75 dB, 4.26 x 10(-5) at 80 dB, and 8.34 x 10(-5) at 85 dB. As compared to the normal subjects, the patients with laryngeal polyps or vocal nodules had significantly reduced vocal efficiency. These results provide quantitative verification of the clinical impression of inefficient phonation in patients with mass lesions of the vocal folds.     

Coordination of aerodynamic and phonatory processes in fluent speech utterances of stutterers

It has often been suggested that there is a close relation between problems in the coordination of respiratory, phonatory, and articulatory processes and dysfluencies in speech production. However, empirical support for this hypothesis is scarce, because most studies of speech behavior have been restricted to a single motor process. The present investigation examines the interactions of respiration (specifically the build up of subglottal pressure), phonation, and articulation. Pressure build-up patterns preceding the onset of phonation were studied in 573 fluent utterances of 10 stutterers and in 552 utterances of 7 control subjects. Stutterers evidenced deviant patterns of subglottal pressure build-up much more often than did control speakers. Electroglottographic records of voice onset were classified as either abrupt or gentle and with respect to the presence or absence of gross irregularities in amplitude (shimmer) and period duration (jitter). Stutterers evidenced abrupt voice onsets significantly more often than did controls. The occurrence of jitter and shimmer, however, did not differ significantly across the groups. Acoustic measures of abruptness of voice onset, first syllable duration, and average syllable duration were also obtained, but they failed to differ significantly between the two groups. This study corroborates previous findings that perceptually fluent utterances of stutterers may differ, on a physiological level, from the speech of nonstutterers.