Laryngeal Muscle Tension Research Articles

A virtual trajectory model predicts differences in vocal fold kinematics in individuals with vocal hyperfunction

A simple, one degree of freedom virtual trajectory model of vocal fold kinematics was developed to investigate whether kinematic features of vocal fold movement confirm increased muscle stiffness. Model simulations verified that increases in stiffness were associated with changes in kinematic parameters, suggesting that increases in gesture rate would affect kinematic features to a lesser degree in vocal hyperfunction patients given the increased levels of muscle tension they typically employ to phonate. This hypothesis was tested experimentally in individuals with muscle tension dysphonia (MTD; N = 10) and vocal nodules (N = 10) relative to controls with healthy normal voice (N = 10) who were examined with trans-nasal endoscopy during a simple vocal fold abductory-adductory task. Kinematic measures in MTD patients were less affected by increased gesture rate, consistent with the hypothesis that these individuals have elevated typical laryngeal muscle tension. Group comparisons of the difference between medium and fast gesture rates (Mann-Whitney, one-tailed) showed statistically significant differences between the control and MTD individuals on the two kinematic features examined (p<0.05). Results in nodules participants were mixed and are discussed independently. The findings support the potential use of vocal fold kinematics as an objective clinical assay of vocal hyperfunction.

The Treatment of Muscle Tension Dysphonia: A Comparison of Two Treatment Techniques by Means of an Objective Multiparameter Approach

The purpose of the present study is to measure the effectiveness of two treatment techniques--vocalization with abdominal breath support and manual circumlaryngeal therapy (MCT)--in patients with muscle tension dysphonia (MTD). The vocal quality before and after the two treatment techniques was measured by means of the dysphonia severity index (DSI), which is designed to establish an objective and quantitative correlate of the perceived vocal quality. The DSI is based on the weighted combination of the following set of voice measurements: maximum phonation time (MPT), highest frequency, lowest intensity, and jitter. The repeated-measures analysis of variance (ANOVA) revealed a significant difference between the objective overall vocal quality before and after MCT. No significant differences were measured between the objective overall vocal quality before and after vocalization with abdominal breath support. This study showed evidence that MCT is an effective treatment technique for patients with elevated laryngeal position, increased laryngeal muscle tension, and MTD. The precise way in which MCT has an effect on vocal quality has not been addressed in this experiment, but merits study. Further research into this topic could focus on electromyography (EMG) recordings in relation to vocal improvements with larger sample of subjects.

Impact of Muscle Tension Dysphonia on Tonal Pitch Target Implementation in Vietnamese Female Teachers

Muscle tension dysphonia (MTD) is a voice disorder with deteriorated vocal quality, particularly pitch problems. Because pitch is mainly controlled by the laryngeal muscles, and because MTD is characterized by increased laryngeal muscle tension, we hypothesized that it may result in problems in pitch target implementation in tonal languages. We examined tonal samples of 42 Vietnamese female primary school teachers diagnosed with MTD and compared them with 30 vocally healthy female teachers who spoke the same dialect. Tonal data were analyzed using Computerized Speech Lab (CSL-4300B) for Windows. From tonal sampling bases, fundamental frequency (F0) was measured at target points specified by contour examination. Parameters representing pitch movement including time, size, and speed of movement were measured for the falling tone and rising tone. We found that F0 at target points in MTD group was lowered in most tones, especially tones with extensive F0 variation. In MTD group, target F0 of the broken tone in isolation was 37.5 Hz lower (P<0.01) and target F0 of rising tone in isolation was 46 Hz lower (P<0.01) than in control group. In MTD group, speed of pitch fall of the falling tone in isolation was faster than control group by 2.2 semitones/second (st/s) (P<0.05) and speed of pitch rise in the rising tone in isolation was slower than control group by 7.2 st/s (P<0.01). These results demonstrate that MTD is associated with problems in tonal pitch variation.

Assessment and treatment of musculoskeletal tension in hyperfunctional voice disorders

Poorly regulated activity of the perilaryngeal muscles affects phonatory function and contributes to a class of disorders known as hyperfunctional or musculoskeletal tension voice disorders. Recognizing the signs and symptoms of excess or dysregulated laryngeal muscle activity is critical to proper diagnosis and selection of appropriate treatment(s). Although numerous approaches exist to manage such hyperfunctional syndromes, manual circumlaryngeal techniques have recently received attention as valuable tools in both assessment and treatment. Therefore, the purpose of this article is to: (1) describe common phenomenological features of dysregulated laryngeal muscle tension, thereby facilitating its recognition, (2) highlight the role of manual circumlaryngeal techniques in assessment and management, (3) survey additional treatment approaches for laryngeal hyperfunction, and explore the evidence to support their effectiveness, and (4) identify unresolved issues and controversies surrounding tension-based voice disorders. A series of pre- and post-treatment audio examples are provided on the journal website at www.informaworld.com/ijslp.

プロトンポンプ阻害剤の投与にて改善したｍｕｓｃｌｅ ｔｅｎｓｉｏｎ ｄｙｓｐｈｏｎｉａの３例

We report 3 cases of muscle tension dysphonia (MTD), all involving women 44 to 68 years old, recovered using proton pump inhibitors (PPI). Case 1 had open posterior commissure (MTD Type I) and Cases 2 and 3 supraglottis compression (MTD Type II, III). It is generally assumed that functional dysphonia with maladjustment of laryngeal muscle tension is caused by improper phonation and/or emotional disorder. Our cases, however, suggest that laryngopharyngeal reflux (LPR) may also relate to the occurrence of MTD.

February 11 Highlights

Liotti et al. followed up on earlier work on Lee Silverman voice treatment efficacy in Parkinson’s disease by studying five Parkinson’s disease patients with PET before and after Lee Silverman voice treatment. After treatment, neural activity as reflected by regional cerebral blood flow was reduced in motor-premotor cortex and increased in basal ganglia, prefrontal cortex, and anterior insula. see page 432 de Swart et al. compared the effectiveness of a newly developed pitch-limiting voice treatment with the Lee Silverman voice treatment (“think loud, think shout”). The new method of instruction “speak loud and low” (illustrated with online video) appeared to yield an immediate improvement of loudness and voice quality, and to prevent frequently-encountered adverse therapy effects on vocal pitch and laryngeal muscle tension seen with Lee Silverman voice treatment. see page 498 Commentary by David Rosenfeld, MD “Speech” is the motor output of language. Human beings readily acquire speech and language during critical periods of development, but have difficulty learning them as adults. Similarly, it is difficult for heretofore normal patients afflicted with brain disease to overcome their dysarthria. However, there are some effective techniques for these patients. In this issue, Liotti et al. document in Parkinson’s patients taught to “think loud, think shout,” a shift in PET activity from premotor cortex to basal ganglia and anterior insula, speculating a change from effortful to more automatic speech production. de Swart et al., also in this issue, …

Vocal Nodules and Laryngeal Morphology

Our purpose was to study the occurrence of vocal fold nodules under conditions of habitual vocal abuse associated with increased laryngeal muscle tension, to identify the existence of a relationship between vocal nodules and laryngeal morphology. We studied one group of 30 subjects with vocal nodules, 18 to 50 years old, who were compared with two control groups, one of females and one of males, consisting of 30 subjects each. The parameters evaluated were: type of vocal folds coaptation, glottic proportion (GP) and abduction angle (AA), obtained by videotelelaryngoscopy. In the nodules group, the larynges presented a mean value of GP similar to that of the female group, both of which were lower than the mean GP value of the male group. On the other hand, the mean AA was lower than the one in the female group, and closer to the one in the male group. We concluded that vocal nodules were present only in larynges with a predominantly young female morphology, with functional limitations of abduction.

Effect of the menstrual cycle on laryngeal muscle tension of singers and nonsingers

Intrinsic laryngeal muscular tension was evaluated by means of electroglottography and laryngostroboscopy in 20 singers and 20 nonsingers every other day for two menstrual cycles. A laryngograph, an oscilloscope, a computer, a sound pressure level meter, and a laryngostroboscope were used for this research. It was revealed that ovulation did not change muscular tension in all subjects. Hypotension was found in both singers and nonsingers. In singers it appeared often in different segments of the cycle, in nonsingers it appeared seldom around menses only. Possible explanations are: muscle hypotension appeared in consequence of laryngeal water retention and edema of vocal folds as a result of the drop in estrogen and progesterone secretion and fluctuation in these hormone levels. It was concluded that compensation for hypotonus required effort and could be a reason for the begining of voice disorders.

Laryngeal biomechanics of the singing voice

By transnasal fiberoptic laryngoscopy, patients with functional voice disorders often demonstrate abnormal laryngeal biomechanics, commonly supraglottic contraction. Appropriately, such conditions are sometimes termed muscle tension dysphonias. Singers working at the limits of their voice may also transiently demonstrate comparable tension patterns. However, the biomechanics of normal singing, particularly for different singing styles, have not been previously well characterized. We used transnasal fiberoptic laryngoscopy to study 100 healthy singers to assess patterns of laryngeal tension during normal singing and to determine whether factors such as sex, occupation, and style of singing influence laryngeal muscle tension. Thirty-nine male and 61 female singers were studied; 48 were professional singers, and 52 were amateurs. Examinations of study subjects performing standardized and nonstandardized singing tasks were recorded on a laser disk and subsequently analyzed in a frame-by-frame fashion by a blinded otolaryngologist. Each vocal task was graded for muscle tension by previously established criteria, and objective muscle tension scores were computed. The muscle tension score was expressed as a percentage of frames for each task with one of the laryngeal muscle tension patterns shown. The lowest muscle tension scores were seen in female professional singers, and the highest muscle tension scores were seen in amateur female singers. Male singers (professional and amateur) had intermediate muscle tension scores. Classical singers had lower muscle tension scores than nonclassical singers, with the lowest muscle tension scores being seen in those singing choral music (41%), art song (47%), and opera (57%), and the highest being seen in those singing jazz/pop (65%), musical theater (74%), bluegrass/country and western (86%), and rock/gospel (94%). Analyzed also were the influences of vocal nodules, prior vocal training, number of performance and practice hours per week, warm-up before singing, race, smoking, and alcohol consumption. (Otolaryngol Head Neck Surg 1996;115:527-37.)

Laryngeal biomechanics of the singing voice.

By transnasal fiberoptic laryngoscopy, patients with functional voice often demonstrate abnormal laryngeal biomechanics, commonly supraglottic contraction. Appropriately, such conditions are sometimes termed muscle tension dysphonias. Singers working at the limits of their voice may also transiently demonstrate comparable tension patterns. However, the biomechanics of normal singing, particularly for different singing styles, have not been previously well characterized. We used transnasal fiberoptic laryngoscopy to study 100 healthy singers to assess patterns of laryngeal tension during normal singing and to determine whether factors such as sex, occupation, and style of singing influence laryngeal muscle tension. Thirty-nine male and 61 female singers were studied; 48 were professional singers, and 52 were amateurs. Examinations of study subjects performing standardized and nonstandardized singing tasks were recorded on a laser disk and subsequently analyzed in a frame-by-frame fashion by a blinded otolaryngologist. Each vocal task was graded for muscle tension by previously established criteria, and objective muscle tension scores were computed. The muscle tension score was expressed as a percentage of frames for each task with one of the laryngeal muscle tension patterns shown. The lowest muscle tension scores were seen in female professional singers, and the highest muscle tension scores were seen in amateur female singers. Male singers (professional and amateur) had intermediate muscle tension scores. Classical singers had lower muscle tension scores than nonclassical singers, with the lowest muscle tension scores being seen in those singing choral music (41%), art song (47%), and opera (57%), and the highest being seen in those singing jazz/pop (65%), musical theater (74%), bluegrass/country and western (86%), and rock/gospel (94%). Analyzed also were the influences of vocal nodules, prior vocal training, number of performance and practice hours per week, warm-up before singing, race, smoking, and alcohol consumption.

The voice of people with Down syndrome: An EMG biofeedback study

The laryngeal muscle tension of a group of thirty people with Down syndrome was compared with that of three other groups of people: those with learning disabilities, those with functional dysphonia (that is a voice disorder caused by misuse of the vocal mechanism) and a normal control group. The scores obtained were analysed by SPSS to determine whether there were significant differences in the way in which voice is produced by the four groups. The chief finding is that the energy level needed to activate the vocal mechanism from its at rest level to its voicing level is almost twice as great for the group with Down syndrome as for the control group. Implications for therapeutic interventions are considered. It is felt that new strategies to aid voicing need to be developed. The importance of keeping up fluid levels is highlighted.

Muscle misuse voice disorders: description and classification.

It is apparent that voice disorders frequently labelled "functional" are associated with laryngeal muscle misuse. This use of the word "functional" is, however, intrinsically ambiguous, and so we propose an alternative term based on descriptive features of dysfunction: "muscle misuse voice disorders". Persistent phonation with an abnormal laryngeal posture can lead to organic changes such as nodules or polyps, particularly in females with posterior glottic chink. We hypothesized that the chink was related to an overall increase in laryngeal muscle tension, and more directly due to inadequate relaxation of the posterior crico-arytenoid muscle during phonation. We employed the term "muscular tension dysphonia" (MTD) to note this condition, but it may be that the term "laryngeal isometric" is superior since there are other misuses of the larynx that obviously are manifestations of abnormalities of muscular tension. With this in mind we have evolved a new classification based on the laryngeal isometric, glottic and supraglottic lateral contraction states, antero-posterior contraction states, conversion aphonia, psychogenic bowing, and adolescent transitional dysphonia.

Development of functional sex differences in the larynx of Xenopus laevis

Three laryngeal properties associated with the production of masculine song--laryngeal muscle tension, fiber twitch type, and fiber recruitment--are markedly sexually dimorphic in adult Xenopus laevis frogs. To elucidate the pattern of sexual differentiation, tension and fiber recruitment in male and female larynges and fiber twitch type in male larynges were examined throughout postmetamorphic development. Masculinization of male laryngeal properties begins early in postmetamorphic development and continues until adulthood. In contrast, tension and fiber recruitment in females do not change after the end of metamorphosis. Laryngeal muscle tension and fiber type are gradually and progressively masculinized; the temporal pattern of masculinization is very similar for these properties. Fiber recruitment, on the other hand, appears to masculinize in a stepwise manner. Masculinization of all three properties is highly correlated with larynx weight in males. We have used this relation to divide postmetamorphic development into seven stages associated with key events in sexual differentiation. This staging scheme provides an important experimental tool for studying the hormonal regulation of sexual differentiation, the subject of the accompanying paper.

EMG biofeedback treatment of pediatric hyperfunctional dysphonia

A 9-year-old boy with a long history of impaired communication resulting from hyperfunctional dysphonia and vocal nodules had proven to be unresponsive to traditional voice therapy. In this study, he engaged in biweekly visual EMG biofeedback training to reduce laryngeal muscle tension. In a multiple baseline design across two responses with changing criteria, results demonstrated sequential stepwise reductions in muscle tension with each new criterion. Concomitant improvements were found in laryngeal aerodynamic functioning and in voice quality. The treatment also resulted in the elimination of the vocal nodules without surgical intervention. These effects were maintained at 6 month follow-up.

Electromyographic biofeedback training with patients exhibiting a hyperfunctional voice disorder.

Baseline EMG measures of general laryngeal area muscle tension while speaking and during silence were taken from a group of 21 normal subjects and 7 subjects diagnosed through indirect laryngoscopy as having vocal nodules. In an attempt to reduce their baseline scores, the vocal nodule patients underwent 8 EMG biofeedback training sessions followed by a 2-week follow-up session. Sophisticated listeners then judged the qualities of the voices produced during the base-line and follow-up sessions. Measures of sound pressure levels for the speech samples were also taken to determine their effects on EMG scores. Results of the statistical analyses revealed that significant differences in general laryngeal area muscle tension while speaking and in silence exist between normal and pathological subjects; and that subjects with vocal nodules could significantly reduce these tension levels with EMG biofeedback training. A positive correlation was then found between the EMG measures and the judgments of voice qualities. No correlations were found between EMG measures and sound pressure levels.