Considerations for Maintenance of Postural Alignment for Voice Production

There is general agreement that postural alignment is important in optimizing voice function. A number of articles have illuminated the way in which posture, particularly of the cervical spine, is directly related to vocal resonance and pitch control. Despite frequent involvement in muscle training, few speech pathologists have the background in exercise physiology necessary to appreciate the contribution of muscular length-tension relationships to postural alignment. The purpose of this article is to provide voice therapists with information to help them formulate appropriate recommendations for improving postural alignment. This article synthesizes information from the literature regarding the role of muscular length-tension balance in the attainment and maintenance of postural alignment. Important considerations in the assessment of muscle tension and weakness are presented along with advice regarding application to the treatment of voice-disordered patients. Concepts detailed include agonist/antagonist relationships, the biomechanics of stretching, postural assessment, and the relationship between muscle tension and muscle weakness. The role of both stretching and strength-based training is discussed. Specific exercises with emphasis on altering the alignment of the cervical and thoracic spine are presented with suggestions for their use in the clinic. There is growing understanding of the physiology behind recommendations of voice teachers and therapists to maintain optimal alignment. To effectively mediate postural misalignment, clinicians must have knowledge of the length-tension relationships between muscles. This understanding will lead to better interventions for postural alignment.     

Coaching Strategies for Behavioral Voice Therapy and Training

Coaching is one of the most common words in our modern vocabulary and has many meanings depending on the setting in which it is used. Coaching facilitates positive changes to achieve a goal, usually through indirect approaches, including improving an individual's outlook on their behaviors or attitudes. Its application has spread beyond the corporate world, and many medical specialties use coaching principles. The goals of this article are to introduce coaching as a profession, and to explore the function of a vocal coach to improve communicative and vocal performance. Moreover, differences between voice therapy and voice training are highlighted, including the principles subjacent to these interventions and the use of coaching strategies. Four strategies of professional coach practitioners adapted to the training and therapy of the voice with applications to both are described. These are: powerful questions, active listening, changing habits, and implementation intention. The use of these strategies may help individuals to achieve high voice performance. Most importantly, the speech-language pathologist voice specialist can apply these strategies particularly in cases of behavioral dysphonias, which can be resistant to traditional voice therapy.     

Effects of back extensor strengthening exercises on postural alignment,physical function and performance,self-efficacy,and quality of life in Japanese community-dwelling older adults: A controlled clinical trial

Objective: To examine the changes in postural alignment and kyphosis-correlated factors after 6 months of back extensor strengthening exercise in a group of community-dwelling older adults aged ≥65 years. Methods: We quasi-randomized 29 subjects into an intervention group treated with a back extensor strengthening program and a control group treated with a full-body exercise program. These groups completed 20-30 minutes of exercise directed by a physical therapist one or more times per week and were instructed to exercise at home as well. The participants were assessed prior to and after the intervention using the following criteria: postural alignment of “usual” and “best” posture, physical function, physical performance, self-efficacy, and quality of life. The differences between two factors (group and period) were compared for each of the measurement variables. Results: Subjects who adequately completed the exercises were analyzed. A reduced knee flexion angle was noted in the “best” posture of both groups, as were improved physical function and performance with the exception of one-leg standing time. Verifying the effect size in the post-hoc analysis, the body parts that showed changes to postural alignment after the intervention differed between groups. Conclusions: Back extensor strengthening exercises improved physical function and performance, but did not improve spinal alignment. The changes due to these interventions were not significantly different from changes observed in the full-body exercise group. However, post-hoc analysis revealed that the effect size of posture change was different, possible indicating that the two groups experienced different changes in the postural alignment.     

Inspiratory pressure threshold training for upper airway limitation: a case of bilateral abductor vocal fold paralysis

A single subject design was used to determine if pressure threshold training strengthens the inspiratory muscles in a subject with a limited glottal airway as well as diminish dyspnea and improve parameters of speech. The subject was a 19-year-old woman whose glottal airway was limited due to bilateral abductor vocal fold paralysis following a thyroidectomy. A 5-week inspiratory muscle strength-training program was implemented using a pressure-threshold trainer to strengthen the inspiratory muscles with the intent of enabling the generation of higher inspiratory pressures. The pressure threshold on the trainer was set at 75% of the subject's maximum inspiratory pressure (MIP). The subject was required to generate sufficient inspiratory pressure to bring air through the trainer during an inspiratory maneuver. MIP was the dependent variable used as an indication of inspiratory muscle strength. MIP increased by 47% following the training program. Maximal minute ventilation and oxygen uptake increased posttraining. Dyspnea during exercise and speech decreased as reported by the subject. Total reading duration and pause duration demonstrated a declining trend during connected speech. The results indicated that inspiratory muscle training using a pressure threshold device improves functional tasks such as exercise and speech in a subject with upper airway limitation.     

The Effects of Comprehensive Exercise Program on the Adjustments of Standing Balance in Community-Dwelling Elderly Persons

The objective of this study was to assess the effect of comprehensive exercise program widely accepted as a community-based physical intervention for the prevention of falling in the elderly persons on their controlling standing balance. Twenty-six community-dwelling elderly persons (13 males and females; 69.8 ± 2.8 years old) participated in this study. Daily exercise was comprised of walking for more than 30 min, stretching, muscle strengthening and balance exercise without exercise equipments. The intervention was continued for three months. Indicators of standing balance related to static balance, dynamic balance and postural response were measured before and after the intervention. As an effect of the intervention on static balance, the sway of center of pressure (COP) in the static stance significantly increased. In the dynamic balance, significant improvements were observed in one leg standing time, the 10-m gait time, functional reach. Additionally, the maximal movable length of COP which subjects can move voluntarily to right and left significantly increased. In the postural response, the integrated electromyography (IEMG) induced by postural response for sudden postural perturbation significantly decreased in the lower leg muscles. Since less muscular activities were sufficient to maintain posture, it was suggested that postural response was elicited more efficiently following the intervention. This study suggested that the comprehensive exercise program, which has been widely introduced as community-based interventions for the prevention of falling, have extensive effects on the control of standing balance covering static balance, dynamic balance and postural response in the elderly persons.     

Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration

Adjustments to cricothyroid and thyroarytenoid muscle activation are critical to the control of fundamental frequency and aerodynamic aspects of vocal fold vibration in humans. The aerodynamic and physical effects of these muscles are not well understood and are difficult to study in vivo. Knowledge of the contributions of these two muscles is essential to understanding both normal and disordered voice physiology. In this study, a three-mass model for voice simulation in adult males was used to produce systematic changes to cricothyroid and thyroarytenoid muscle activation levels. Predicted effects on fundamental frequency, aerodynamic quantities, and physical quantities of vocal fold vibration were assessed. Certain combinations of these muscle activations resulted in aerodynamic and physical characteristics of vibration that might increase the mechanical stress placed on the vocal fold tissue.     

Physiological Studies of Retrusive Movements of the Human Tongue

SUMMARY: This study identified that physiologically the superior pharyngeal constrictor muscle at the level of the base of the tongue contributes to retrusive movement of the tongue with constriction of the mid-pharyngeal cavity and possesses unique properties in terms of motor speech control along with the genioglossus muscle. From a kinematic study involving trans-nasal fiberscopy and lateral X-ray fluorography, retrusive movement of the tongue was highly correlated with constrictive movement of the mid-pharyngeal cavity. An electromyographic study revealed that the superior pharyngeal constrictor muscle at the level of the base of the tongue contributes to retrusive movement of the tongue and that the genioglossus muscle contributes to protrusive movement. We also noted that this relationship between the activities of these two muscles were in response to postural changes during vowel productions without changes in the acoustic features. These findings suggest that these two muscles act not only antagonistically to produce retrusive and protrusive movement of the tongue, but also they complement each other to conserve the shape of the vocal tract for speech production. The functional relationship between these two muscles could contribute the consecutive movement of human speech production under various conditions and might be useful when applying rehabilitation approaches for the patients with neurological speech and swallowing disorders.     

The role of strap muscles in phonation—In vivo caninelaryngeal model

In spite of the presumed importance of the strap muscles on laryngealvalving and speech production, there is little research concerning the physiological role and the functional differences among the strap muscles. Generally, the strap muscles have been shown to cause a decrease in the fundamental frequency (F₀) of phonation during contraction. In this study, an in vivo canine laryngeal model was used to show the effects of strap muscles on the laryngeal function by measuring the F₀, subglottic pressure, vocal intensity, vocal fold length, cricothyroid distance, and vertical laryngeal movement. Results demonstrated that the contraction of sternohyoid and sternothyroid muscles corresponded to a rise in subglottic pressure, shortened cricothyroid distance, lengthened vocal fold, and raised F₀ and vocal intensity. The thyrohyoid muscle corresponded to lowered subglottic pressure, widened cricothyroid distance, shortened vocal fold, and lowered F₀ and vocal intensity. We postulate that the mechanism of altering F₀ and other variables after stimulation of the strap muscles is due to the effects of laryngotracheal pulling, upward or downward, and laryngotracheal forward bending, by the external forces during strap muscle contraction.     

Behavior of laryngeal muscles of the late William Vennard

Behavior of the cricothyroid, lateral cricoarytenoid, vocalis, and interarytenoid muscles of William D. Vennard was electromyographically investigated. This article demonstrates electromyographic recordings that have not been published. Data presentation and discussion are focused on vocal registers, some phrases for voice training and warm-up, vowels, phonation modes, fundamental frequency control, the interarytenoid muscle, and some nonsinging behaviors     

The Activity Patterns of Neck Muscles in Professional Classical Singing

The study aimed to characterize the activity patterns of neck muscles during classical singing. Muscle usage during inhalation and phonation and the relationship to changes in pitch and vocal loudness was of particular interest. Five professional opera singers (2 males, 3 females) participated. Surface electromyographic activity (EMG) was recorded from the upper trapezius (TR), the sternocleidomastoideus (STM), and the scalenus (SC) muscles and the muscles in the posterior neck region (PN). EMG activity in TR and STM was lowered by EMG biofeedback (BF), and the possible effect of lowered EMG activity in these muscles on the EMG activity of SC and PN was analyzed. A strain gauge sensor recorded the chest circumference of the thorax. Three singing tasks were performed. Each task was performed three times with variation in vocal loudness and pitch. After the first performance of the singing tasks, the BF session was carried out. Thereafter muscle activity was recorded in repeat performances of the same tasks, and the EMG amplitude of all muscles was compared before and after BF. We conclude that STM and SC showed correlated activity patterns during inhalation and phonation by classical singers. Second, substantial muscle activity was observed in PN during inhalation and phonation. BF performed on TR and STM had a secondary effect of lowering EMG activity in SC and PN. The activity of all neck muscles was markedly elevated when singing in the highest pitch. There was no consistent task-based difference in EMG amplitude for the other singing tasks.     

Postural Sway during Local Vibratory Stimulation for Proprioception in Elderly Individuals with Pre-Sarcopenia

Objective: Many studies have demonstrated that the loss of muscle mass (LMM) poses a risk of postural instability in the elderly; however, few studies have shown how LMM decreases proprioception. In this study, we investigated the changes in postural sway among older individuals with LMM induced by application of a local vibratory stimulus. Method: We enrolled 64 older adults (mean age). Postural sway was measured while applying vibration stimuli of 30, 60, and 240 Hz to both the gastrocnemius and lumbar multifidus muscles. We also measured the relative proprioceptive weighting ratio (RPW) of postural sway. The patients were divided into LMM and non-LMM (NLMM) groups. The study subjects were compared in terms of their age, height, weight, body mass index (BMI), lower leg skeletal muscle mass index (LSMI), L4/5 lumbar multifidus cross-sectional area ratio, and RPW at 30, 60, and 240 Hz. Results: Subjects in the LMM group showed a significantly lower RPW at 60 Hz, LSMI, and BMI than did those in the NLMM group. Conclusions: Decrease in RPW with 60-Hz stimulation concerning the lower leg proprioception is a risk factor for LMM-associated postural instability in the elderly. Consequently, with respect to the gastrocnemius muscles proprioception in LMM, it is necessary to perform assessments using muscle spindle stimuli.     

Cooperative Regulation of Vocal Fold Morphology and Stress by the Cricothyroid and Thyroarytenoid Muscles

Voice is produced by vibrations of vocal folds that consist of multiple layers. The portion of the vocal fold tissue that vibrates varies depending primarily on laryngeal muscle activity. The effective depth of tissue vibration should significantly influence the vibrational behavior of the tissue and resulting voice quality. However, thus far, the effect of the activation of individual muscles on the effective depth is not well understood. In this study, a three-dimensional finite element analysis is performed to investigate the effect of the activation of two major laryngeal muscles, the cricothyroid (CT) and thyroarytenoid (TA) muscles, on vocal fold morphology and stress distribution in the tissue. Because structures that bear less stress can easily be deformed and involved in vibration, information on the morphology and stress distribution may provide a useful estimate of the effective depth. The results of the analyses indicate that the two muscles perform distinct roles, which allow cooperative control of the morphology and stress. When the CT muscle is activated, the tip region of the vocal folds becomes thinner and curves upward, resulting in the elevation of the stress magnitude all over the tissue to a certain degree that depends on the stiffness of each layer. On the other hand, the TA muscle acts to suppress the morphological change and controls the stress magnitude in a position-dependent manner. Thus, the present analyses demonstrate quantitative relationships between the two muscles in their cooperative regulation of vocal fold morphology and stress.     

Length-tension relationship of the feline thyroarytenoid muscle

Vocal fold tension during phonation is generated by coordinated contraction of the intrinsic laryngeal muscles. The thyroarytenoid muscle has been found to have increased stiffness at various levels of strain when compared with other intrinsic laryngeal muscles. The objective here is to test the hypothesis that the thyroarytenoid muscle exhibits high passive tension during maximal isometric tetanic force generation, and to test the hypothesis that the thyroarytenoid maintains the ability to generate contractile force at high levels of strain more effectively than other skeletal muscle. The thyroarytenoid muscles (n=9) and digastric muscle strips (n=7) were removed from adult random-bred cats. Maximal isometric tension and passive tension at optimum length were measured from each muscle in vitro. Active and passive length-tension curves were constructed for each muscle. The contractile properties of the thyroarytenoid group were compared with those of the digastric muscle group. The thyroarytenoid muscle group required on average 140 mN of passive tension to generate maximal isometric tetanic tension. This represented 39% of the average maximal isometric tetanic tension generated by the muscles. These results were significantly higher than the digastric muscle group, which required on average 28 mN of passive tension (9% of maximal isometric tetanic tension, p<0.05). At 110% of optimum length, the thyroarytenoid muscle maintained 89.8% of maximal isometric tetanic force, whereas the digastric muscle group maintained 67.7% of maximal isometric tetanic force (p<0.05). The thyroarytenoid muscle exhibits higher passive tension when generating maximal isometric tension than the digastric muscle control group. The thyroarytenoid muscle maintains higher levels of active tension at high strain than the digastric muscle control group. We conclude that these findings are related to the ability of the thyroarytenoid muscle to function as a fine tensor of the vocal fold in a high strain environment.     

Phonetogram Changes for Trained Singers Over a Nine-Month Period of Vocal Training

Professional vocalists encounter demands requiring voluntary control of phonation, while utilizing a considerable range of frequency and intensity. These quantifiable acoustic events can be measured and represented in a phonetogram. Previous research has compared the phonetograms of trained and untrained voices and found significant differences between these groups. This study was designed to assess the effects of vocal training for singers over a period of nine months. Phonetogram contour changes were examined, with the primary focus on expansion of frequency range and/or intensity control. Twenty-one first-year, master's level, vocal music students, who were engaged in an intensive vocal performance curriculum, participated in this study. Following nine months of vocal training, significant differences were revealed in the subjects' mean frequency range and minimum vocal intensity across frequency levels. There was no significant difference for the mean maximum vocal intensity across frequency levels following vocal training.     

Vocal fold strain and vocal pitch in singing:Radiographic observations of singers and nonsingers

The relationship between vocal fold strain and vocal pitch in singersand nonsingers singing a rising pitch series has been indirectly investigated by means of lateral radiographs. Nonsingers tend to exhibit more strain than singers. To standardize the degree of strain, an index of strain per semitone is proposed. The semitone strain indicates the average amount of strain per 1 semitone of pitch increase or decrease. The index has been shown to be affected by several factors: gender, singing training, singing technique, voice class, age, and status of muscle function. Observations suggest that similar groups of individuals occupy different positions on the stress-strain curve, indicated by their semitone strain values.     

Botulinum toxin in the treatment of recalcitrant mutational dysphonia

Mutational falsetto is the failure of the normal drop in vocal pitch at puberty. Voice therapy almost always achieves an appropriate pitch; however, in cases of failure, surgical treatment has also been recommended. We report a case of a 47-year-old man with an above-average fundamental frequency and a thin voice quality in the absence of any signs of androgen insufficiency. Laryngeal examination revealed atrophy of the vocalis muscle. Voice therapy was unsuccessful in achieving a stable voice. Injection of 15 units of botulinum toxin into each cricothyroid muscle initially resulted in aphonia, but the voice returned by 1 week. Average fundamental frequency was 84 Hz at 1 week, 104 Hz at 1 month, and 100 Hz at 1 year. We hypothesize that mutational dysphonia is an habitual dysfunction of the voice with inappropriate activation of the cricothyroid muscle and disuse of laryngeal adductor muscles. Temporary deactivation of the cricothyroid muscle enforces adoption of a more appropriate vocal mechanism. Botulinum toxin as an adjunct to voice therapy should be considered before surgical alteration of the glottis in patients with recalcitrant mutational falsetto.     

Performance Anxiety: Loss of the Spoken Edge

The study aimed to assess whether a specific training program in vocal and physical skills could reduce the level of perceived performance anxiety. Eighteen undergraduate performing arts students were divided into two even groups. The experimental group experienced 10 two-hour sessions in a specialized vocal and physical skills training program. The control group received the same number of sessions in text analysis by the same teacher. Ten weeks after the training period, both groups were videotaped delivering a short speech of general interest. The videotaped material was assessed by four judges, using a visual analog scale (VAS). Perceptual variables considered were eight vocal and physical features: physical ease, physical presence, effective gesture use, effective eye contact, correct breath use, suitable pace, vocal variety, speech clarity, and one performance feature: perceived performance anxiety. Results indicated that the particular vocal and physical skills training program used showed positive results in effectively reducing the level of perceived performance anxiety. The experimental group scored significantly higher on each of the eight vocal and physical features and significantly lower on the perceived anxiety feature than the control group. This research has implications for those affected by performance anxiety in vocal presentation.     

The effects of excessive vocalization on acoustic and videostroboscopic measures of vocal fold condition

Although dysphonia is a recognized consequence of acute vocal abuse, associated changes in vocal fold appearance and function are not well understood. To document these presumed effects of vocal abuse, audio recordings of sustained vowel production were obtained from 42 drill sergeants daily during the first 6 days of a vocally demanding training exercise. Acoustic analysis showed abnormal levels of jitter and shimmer on Day 1 in 16 of the 42 subjects. Considering only the 26 subjects who showed normal voice acoustics on Day 1, the median levels of jitter and shimmer varied little over the course of training, and significant increases in jitter and shimmer were not seen during the study period. However, the distributions for both jitter and shimmer became more positively skewed and showed a greater number of positive outliers over the course of training. This trend was attributed to 11 subjects who showed two or more instances of abnormal voice acoustics over Days 2 through 6. Laryngeal videostroboscopic recordings of sustained vowel production also were obtained prior to and following training. Perceptual ratings of these recordings by 2 observers revealed significant increases in vocal fold edema, erythema, and edge irregularity, and decreases in vocal fold mucosal wave and amplitude of excursion following the 5-day training period. In general, there was considerable intersubject variability in the extent of acoustic and videostroboscopic effects over the course of training. Of the two types of data, videostroboscopy appears to provide a more sensitive indication of the effects of excessive vocalization.     

Inspiratory pressure threshold training for glottal airway limitation in laryngeal papilloma

A single-subject design was used to determine if inspiratory pressure threshold training increases inspiratory muscle strength and reduces the sensation of dyspnea during exercise and speech. The subject was a 23-year-old female with congenital juvenile papilloma which has been in remission for 10 years. A 4-week inspiratory muscle training program was implemented using an inspiratory pressure threshold trainer. The pressure threshold of the trainer was set by the experimenter. The pressure threshold setting of the trainer was based on a percentage of the subject's maximum inspiratory pressure measured prior to training. The average range of the pressure threshold was 40 to 70 cmH2O. In order for inspiratory air to flow, the subject generated inspiratory pressure, independent of airflow rate. Maximum inspiratory pressure (MIP) was the dependent variable used as the index of inspiratory muscle strength. Exercise dyspnea was a dependent variable rated by the subject during a progressive treadmill test. Dyspnea associated with speech was rated following production of a comfortable and loud speech task. MIP increased by 57% following the training program with a 2-scale point reduction in the perception of dyspnea during exercise. Dyspnea during loud speech decreased from moderate to mild. The changes in dyspnea, both during exercise and speech, are directly related to inspiratory muscle strengthening. The results suggest that inspiratory muscle training may improve respiratory related function in patients with restrictive upper airway disorders.     

Neuromuscular control of fundamental frequency and glottal posture at phonation onset

The laryngeal neuromuscular mechanisms for modulating glottal posture and fundamental frequency are of interest in understanding normal laryngeal physiology and treating vocal pathology. The intrinsic laryngeal muscles in an in vivo canine model were electrically activated in a graded fashion to investigate their effects on onset frequency, phonation onset pressure, vocal fold strain, and glottal distance at the vocal processes. Muscle activation plots for these laryngeal parameters were evaluated for the interaction of following pairs of muscle activation conditions: (1) cricothyroid (CT) versus all laryngeal adductors (TA/LCA/IA), (2) CT versus LCA/IA, (3) CT versus thyroarytenoid (TA) and, (4) TA versus LCA/IA (LCA: lateral cricoarytenoid muscle, IA: interarytenoid). Increases in onset frequency and strain were primarily affected by CT activation. Onset pressure correlated with activation of all adductors in activation condition 1, but primarily with CT activation in conditions 2 and 3. TA and CT were antagonistic for strain. LCA/IA activation primarily closed the cartilaginous glottis while TA activation closed the mid-membranous glottis.