Effect of Clinical Expertise on Efficacy of Vocal Function Exercises in Individuals With Typical Voice.

OBJECTIVES/HYPOTHESIS: To determine the effect of clinical expertise on efficacy of Vocal Function Exercises (VFEs) as measured by change in percent of maximum phonation time goal attained. The hypothesis was that clinical expertise would result in greater increases in percent of maximum phonation time goal attained. STUDY DESIGN: Randomized controlled trial. METHODS: A convenience sample of 19 individuals with typical voice was recruited in a university academic clinic setting. All participants completed baseline assessment and 17 completed all study procedures. Participants were randomized to receive VFEs from an expert voice clinician with more than 40 years' experience (expert group (EG)) or from a master's student in Communication Sciences and Disorders trained in VFEs (novice group (NG)). The primary outcome measure was change in percent of maximum phonation time goal attained during VFE tasks 1 and 4. RESULTS: Mean change scores for maximum phonation time were 27.71 (P = 0.001) and 25.31 (P = 0.003) for EG and NG, respectively. Both groups improved significantly on the primary outcome measure, but the difference between groups was not statistically significant (P = 0.759). A Hedges'-g effect size of -0.14 [-1.10, 0.81] was obtained comparing EG and NG groups, indicating a small negative effect of limited clinical expertise on VFE outcomes in individuals with typical voice. CONCLUSIONS: Speech-language pathologists with varied levels of expertise are capable of efficaciously administering VFEs in individuals with typical voice.

The Effect of Maximum Phonation Time Goal on Efficacy of Vocal Function Exercises.

OBJECTIVES/ HYPOTHESIS: To determine the effect of maximum phonation time goal on efficacy of Vocal Function Exercises (VFEs) as measured by percent of maximum phonation time goal attained. The hypothesis was that provision of a maximum phonation time goal would result in greater increases in percent of maximum phonation time goal attained. STUDY DESIGN: Randomized controlled trial. METHODS: A convenience sample of individuals with normal voice were recruited in a university academic clinic setting. Of 34 participants who volunteered for the study, 28 completed baseline assessment and 19 completed all study procedures. Participants were randomized to complete VFEs with knowledge of their maximum phonation time goal (standard goal, SG), with knowledge of their maximum phonation time goal after three weeks (delayed goal, DG), or without knowledge of their maximum phonation time goal (no goal, NG). The primary outcome measure was percent of maximum phonation time goal obtained during VFE tasks one and four. RESULTS: Mean change scores for maximum phonation time were 32.50 (SG), 34.55 (DG), and 21.02 (NG). Hedges' g effect sizes of -0.10 (-1.19, 0.99) and 0.56 (-0.55, 1.67) were obtained comparing DG and SG groups, and NG and SG groups, respectively. CONCLUSIONS: Absence of maximum phonation time goal attenuates VFE efficacy; maximum phonation time goal is an active ingredient within VFEs.

The Relationship Between Health-Related Quality of Life and Lower-Extremity Visuomotor Reaction Time in Young Adult Women Following Ankle Sprain.

CONTEXT: Many individuals who sustain a lateral ankle sprain (LAS) fail to return to prior activity due to residual symptoms; and report elevated levels of injury-related fear, decreased function, and decreased health-related quality of life (HRQOL). Additionally, individuals with history of LAS exhibit deficits in neurocognitive functional measures like visuomotor reaction time (VMRT), which contributes to worse patient-reported outcome scores. The aim of this study was to examine the relationship between HRQOL and lower-extremity (LE) VMRT in individuals with LAS history. DESIGN: Cross-sectional. METHODS: Young adult female volunteers with history of LAS (n = 22; age = 24 [3.5] y; height = 163.1 [9.8] cm; mass = 65.1 [11.5] kg; and time since last LAS = 67.8 [50.5] mo) completed HRQOL outcomes including the following: (1) Tampa Scale of Kinesiophobia-11, (2) Fear-Avoidance Beliefs Questionnaire, (3) Penn State Worry Questionnaire, (4) modified Disablement in the Physically Active Scale, and (5) Foot and Ankle Disability Index (FADI). Additionally, participants completed a LE-VMRT task by responding to a visual stimulus using their foot to deactivate light sensors. Participants completed trials bilaterally. Separate Spearman rho correlations were performed to assess the relationship between patient-reported outcomes assessing constructs of HRQOL and LE-VRMT bilaterally. Significance was set at P < .05. RESULTS: There was a strong, significant negative correlation between FADI-Activities of Daily Living (ρ = -.68; P = .002) and FADI-Sport (ρ = -.76; P = .001) scores and injured limb LE-VMRT; moderate, significant negative correlations between the uninjured limb LE-VMRT and FADI-Activities of Daily Living (ρ = -.60; P = .01) and FADI-Sport (ρ = -.60; P = .01) scores; and moderate, significant positive correlations between the injured limb LE-VMRT and modified Disablement in the Physically Active Scale-Physical Summary Component (ρ = .52; P = .01) and modified Disablement in the Physically Active Scale-Total (ρ = .54; P = .02) scores. All other correlations were not statistically significant. CONCLUSIONS: Young adult women with history of LAS demonstrated an association between self-reported constructs of HRQOL and LE-VMRT. As LE-VMRT is a modifiable injury risk factor, future studies should examine the effectiveness of interventions designed to improve LE-VMRT and the impact on self-reported HRQOL.

Vocal Function Exercises With and Without Maximally Sustained Phonation: A Randomized Controlled Trial of Individuals With Normal Voice.

OBJECTIVES: To determine the effect of maximally sustained phonation on efficacy of Vocal Function Exercises as measured by percent of maximum phonation time goal attained. The hypothesis was that maximally sustained phonation would result in greater improvements in percent of maximum phonation time goal attained. STUDY DESIGN: Randomized controlled trial. METHODS: A convenience sample of individuals with normal voice were recruited in a university academic clinic setting. Of 34 participants who volunteered for the study, 31 completed baseline assessment and 23 completed all study procedures. Participants were randomized to complete Vocal Function Exercises (traditional group TG), modified Vocal Function Exercises with reduced requirement for maximally sustained phonation (midpoint group MG), or modified Vocal Function Exercises with removed requirement for maximally sustained phonation (baseline group BG). The primary outcome measure was percent of maximum phonation time goal obtained during Vocal Function Exercises. RESULTS: The MG (p = 0.008) and TG (p = 0.001) groups significantly improved percent of maximum phonation time goal attained after six weeks of exercise, while the BG group (p = 0.0202) did not (ɑ = 0.0125). Difference among groups was not statistically significant (p = 0.67, ɑ = 0.0125). Hedges' g effect sizes of 0.29 (-0.66, 1.25) and 0.51 (-0.57, 1.58) were obtained comparing MG and TG groups, and BG and TG groups, respectively. CONCLUSIONS: Greater requirements for maximally sustained phonation improved efficacy of Vocal Function Exercises in enhancing normal voice as measured by percent of maximum phonation time goal attained. Maximally sustained phonation may be modified to some extent while preserving efficacy of Vocal Function Exercises, however complete elimination of maximally sustained phonation may attenuate improvement. Additional research in a clinical population is warranted.

Perceived exercise habits of individuals with Parkinson's disease living in the community.

CONTEXT: Exercise has been shown to improve gait in individuals with Parkinson's disease (PD). Stepping practice at higher intensity levels has been suggested as a beneficial treatment option to improve gait in the neurological population. Unfortunately, this mode is poorly understood and underutilized within the PD population. Information on what individuals with PD are doing for exercise would be beneficial to help tailor exercise programs to improve gait and provide exercise options in the community for intensity-based exercise. OBJECTIVE: To investigate the current exercise habits of individuals living with PD in the community aimed at improving walking and to understand the impact of perceived intensity on daily exercise practices. DESIGN SETTING PARTICIPANTS: One hundred thirty-eight individuals with PD living in the community were surveyed online regarding their current exercise habits. MAIN OUTCOME MEASURE: A total of 22 questions aimed to understand exercise selection, focus, and perceived intensity. Questions asked basic demographic, symptom presentation and management of disease related symptoms that were present while living with PD. Exercise questions focused understanding participants current function level, practice exercise habits and perceived levels of exercise intensity during daily routines. RESULTS: Of the 138 individuals surveyed for this preliminary study, eighty-seven percent of individuals with PD participated in exercise with seventy-five percent choosing walking as a mode for exercise. Sixty-five percent of the respondents noted that despite exercise, their walking speed and endurance has worsened since diagnosis. Eighty-one percent perceived exercising at moderate intensity levels, however little provocation of intensity symptoms was noted. CONCLUSION: Our preliminary study survey results suggest that individuals with PD are exercising but not at high enough intensity levels to promote improvements in gait performance. Individuals with PD may need to be pushed at higher intensity levels, beyond their voluntary limits, to induce gait performance changes. These findings can provide a foundation for future fitness interventions within this population to target improving gait.

Implementation of In vivo exposure therapy to decrease injury-related fear in females with a history of ACL-Reconstruction: A pilot study.

OBJECTIVE: The objective of this pilot study was to examine the preliminary feasibility and efficacy of in vivo exposure therapy (IVET) to decrease injury-related fear in females with history of ACLR. DESIGN: Pilot Study. SETTING: Sports Medicine Research Laboratory. PARTICIPANTS: 12 female participants with history of ACLR (≥ 1 year post-operative) were randomized into a 5-week IVET group (n = 6) or 5-week sham physical activity (PA) monitoring group (n = 6). MAIN OUTCOME MEASURES: The independent variables were Group and Time. The dependent variables were the Photographic Series of Sports Activities for ACLR (PHOSA-ACLR) and the Tampa Scale of Kinesiophobia-11 (TSK-11) scores. A Group x Time repeated measures two-way analysis of variance was completed for the PHOSA-ACLR and the TSK-11. Partial η2 effect sizes were used to examine clinically meaningful differences. RESULTS: High retention and adherence rates were observed in the intervention group. The PHOSA-ACLR exhibited a significant main effect for Time (F1,10 = 9.92, p = 0.01, partial η2 = 0.50), but not for Group. No statistically significant or clinically meaningful differences were observed for the TSK-11. CONCLUSION: Both groups exhibited decreased injury-related fear for specific functional tasks. Future research should further examine the efficacy of IVET and PA monitoring to decrease injury-related fear in patients after ACLR.

Resting state functional connectivity responses post-mild traumatic brain injury: a systematic review.

Mild traumatic brain injuries (mTBI) are associated with functional network connectivity alterations throughout recovery. Yet, little is known about the adaptive or maladaptive nature of post-mTBI connectivity and which networks are predisposed to altered function and adaptation. The objective of this review was to determine functional connectivity changes post-mTBI and to determine the adaptive or maladaptive nature of connectivity through direct comparisons of connectivity and behavioral data. Literature was systematically searched and appraised for methodological quality. A total of 16 articles were included for review. There was conflicting evidence of post-mTBI connectivity responses as decreased connectivity was noted in 4 articles, 6 articles reported increased connectivity, 5 reported a mixture of increased and decreased connectivity, while 1 found no differences in connectivity. Supporting evidence for adaptive post-mTBI increases in connectivity were found, particularly in the frontoparietal, cerebellar, and default mode networks. Although initial results are promising, continued longitudinal research that systematically controls for confounding variables and that standardizes methodologies is warranted to adequately understand the neurophysiological recovery trajectory of mTBI.

Neuroplasticity in Corticolimbic Brain Regions in Patients After Anterior Cruciate Ligament Reconstruction.

CONTEXT: Fear has been cited as the primary barrier to return to sport (RTS) by athletes after anterior cruciate ligament reconstruction (ACLR). Understanding the neural factors that contribute to fear after ACLR may help us to identify interventions for this population. OBJECTIVE: To characterize the underlying neural substrate of injury-related fear in patients after ACLR versus healthy matched control individuals during a picture imagination task (PIT) consisting of sport-specific images and images of activities of daily living (ADL). DESIGN: Case-control study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 24 right-hand-dominant participants (12 with left-sided ACLR and 12 control individuals) were enrolled. Participants underwent full-brain functional magnetic resonance imaging. MAIN OUTCOME MEASURE(S): Functional data were acquired using blood oxygen level-dependent (BOLD) echoplanar imaging. Independent t tests were conducted to identify between-groups differences in BOLD signal changes during all images of the PIT. Paired t tests were computed to examine differences in BOLD signal change between sport-specific and ADL images in the ACLR group. RESULTS: Increased activation in the inferior parietal lobule and the mediodorsal thalamus was observed during PIT in the ACLR group. An inability to suppress the default mode network in the ACLR group was noted. The ACLR group exhibited increased activation in the cerebellum and inferior occipital regions during the sport-specific images versus the ADL images, but no other regions of interest demonstrated differences. CONCLUSION: After ACLR, patients may be more predisposed to fear, anxiety, and pain during sport-specific activities and ADLs. Psychosocial interventions may be warranted after ACLR to reduce injury-related fear and mitigate potentially maladaptive neuroplasticity.

Does a Systematic Vocal Exercise Program Enhance the Physiologic Range of Voice Production in Classical Singing Graduate-Level Students?

Purpose The purpose of this study was to assess the effects of vocal function exercises (VFEs) on the physiologic range of the operatic voice. The primary outcome measure was total voice range profile (VRP) area. Method Forty graduate-level opera majors were randomly assigned to experimental (training with VFE + vocal hygiene) and control (vocal hygiene only) groups. All participants underwent an acoustic voice assessment (modified VRP) pre and post 10 weeks of the assigned intervention. VRP total area was calculated and compared between and within the two groups. The total VRP area was subsequently divided into three area thirds (low, medium, and high). Results A significant improvement (increase) was observed in the VFE group for the primary outcome measure of VRP area when pre- and postvoice conditions were compared for total area, upper third, and middle third. No significant improvement was found in the vocal hygiene-only group. Conclusion Vocal training with VFEs over a 10-week period demonstrated positive effects on physiologic voice range as evidenced by an increase in the total VRP area and therefore may enhance the potential of those who already have professional voice training.

Limbic and cortical control of phonation for speech in response to a public speech preparation stressor.

Knowledge on brain networks subserving vocalization in vocally healthy individuals under various task conditions is scarce but paramount to understand voice disorders. The aims of our study were to determine (1) the effect of social-evaluative stress on the central neural control of phonation underlying speech production; and (2) the neural signature, personality profile, and aerodynamic vocal function in relation to salivary cortisol responses. Thirteen vocally healthy females underwent an event-related sparse-sampling fMRI protocol consisting of voiced and whispered sentence productions with and without exposure to the social-evaluative stressor public speaking anticipation. Participants completed a personality questionnaire, rating scales of negative emotional state, and provided salivary cortisol samples. In the total sample, the task contrast of voiced productions revealed that stressor exposure resulted in a peak activation in the right caudate with concomitant deactivations in the bilateral pgACC and aMCC, and right IFG, BA 9, BA 10, insula, putamen, and thalamus. There were individual differences in stressor-induced brain activations as a function of stress reactivity with greater cortisol reactivity linked with lower laryngeal motor cortex activity and lower scores on aspects of extraversion. Our data confirm that stress alters the phonatory control for speech production through limbic-motor interactions. The findings support the Trait Theory of Voice Disorders (Roy and Bless 2000) and help provide critical insights to the study of voice disorders such as primary muscle tension dysphonia.

Biobehavioral Measures of Presbylaryngeus.

OBJECTIVE: The objective of this observational study was to assess the relationship between established aging biobehavioral measures and voice decline in normally aging adults. STUDY DESIGN: Cross-sectional study. METHODS: Participants 60-85 years of age were divided into two age and sex-matched groups, based on the presence or absence of presbylaryngeus. Both groups underwent a battery of tests measuring anthropometric variables, inflammatory markers, general health measures, and vocal function parameters. Differences from the norm were calculated for all variables. Parametric and nonparametric tests were performed to assess group differences. In addition, variable selection analysis was performed to determine variables that were most influential in predicting the occurrence of presbylaryngeus in our current sample. RESULTS: Fifty-three participants were divided into age and sex-matched groups of "presbylaryngeus" (n = 26) and "non-presbylaryngeus" (n = 27). The two groups were statistically different in select measures of inflammatory markers, general health measures, and vocal function parameters. Anthropometric measures were not statistically different. Based on variable selection, the variables most predictive of the presence of presbylaryngeus were measures of the Physical Activity Scale of the Elderly, C-reactive protein, laryngeal airway resistance, and vocal roughness. CONCLUSIONS: In addition to group differences in vocal function measures, results for the presbylaryngeus group consistently trended sub-optimally on anthropometric measures, two inflammatory markers, and general health measures. These results suggest that this sample of individuals with presbylaryngeus demonstrated greater biobehavioral deficits associated with aging as compared to age and sex-matched non-presbylaryngeus individuals.

Descriptive Analysis of the Interactive Patterning of the Vocalization Subsystems in Healthy Participants: A Dynamic Systems Perspective.

Purpose Normative data for many objective voice measures are routinely used in clinical voice assessment; however, normative data reflect vocal output, but not vocalization process. The underlying physiologic processes of healthy phonation have been shown to be nonlinear and thus are likely different across individuals. Dynamic systems theory postulates that performance behaviors emerge from the nonlinear interplay of multiple physiologic components and that certain patterns are preferred and loosely governed by the interactions of physiology, task, and environment. The purpose of this study was to descriptively characterize the interactive nature of the vocalization subsystem triad in subjects with healthy voices and to determine if differing subgroups could be delineated to better understand how healthy voicing is physiologically generated. Method Respiratory kinematic, aerodynamic, and acoustic formant data were obtained from 29 individuals with healthy voices (21 female and eight male). Multivariate analyses were used to descriptively characterize the interactions among the subsystems that contributed to healthy voicing. Results Group data revealed representative measures of the 3 subsystems to be generally within the boundaries of established normative data. Despite this, 3 distinct clusters were delineated that represented 3 subgroups of individuals with differing subsystem patterning. Seven of the 9 measured variables in this study were found to be significantly different across at least 1 of the 3 subgroups indicating differing physiologic processes across individuals. Conclusion Vocal output in healthy individuals appears to be generated by distinct and preferred physiologic processes that were represented by 3 subgroups indicating that the process of vocalization is different among individuals, but not entirely idiosyncratic. Possibilities for these differences are explored using the framework of dynamic systems theory and the dynamics of emergent behaviors. A revised physiologic model of phonation that accounts for differences within and among the vocalization subsystems is described. Supplemental Material https://doi.org/10.23641/asha.7616462.

Vocal function exercises for normal voice: The effects of varying dosage.

PURPOSE: This study examined the effect of varying dosage of vocal function exercise (VFE) home practice on attainment of pre-established maximum phonation time (MPT) goals in individuals with normal voice. High dosage VFE practice was expected to result in greatest MPT. The overarching goal of this study was to contribute to a VFE dosage-response curve, potentially including a point of observable toxicity. METHOD: Twenty-eight females ages 18-25 with normal voice participated in this pre-post longitudinal group study. Participants were randomly assigned to one of three experimental groups and completed a six-week VFE protocol with practice twice daily. The low dosage group performed each exercise once, the traditional group twice, and the high dosage group four times. The primary outcome measure was MPT as performed on the fourth VFE using the prescribed semi-occluded vocal tract posture. RESULT: No toxic effects were observed. MPT increased for all participants, with significant improvement for traditional and high dosage groups. CONCLUSION: High dosage VFEs may yield more rapid improvement in MPT, however benefits must be weighed against the risk of increased attrition. Low dosage VFEs insufficiently improved MPT. Further research on dosage is warranted, and should include individuals with disordered voice.

Vocal function exercises for normal voice: With and without semi-occlusion.

PURPOSE: This study examined the effect of varying degrees of vocal tract (VT) occlusion used during Vocal Function Exercises (VFEs) on attainment of maximum phonation time (MPT) goals in normal voice. Greater VT occlusion was expected to result in increased MPT. The overarching goal was to determine whether the semi-occluded vocal tract (SOVT) posture used during VFEs could be modified while preserving efficacy. METHOD: Twenty-six females ages 18-30 participated in this pre-post longitudinal group study. Participants were randomly assigned to three experimental groups and completed a six-week VFE protocol. The first group performed exercises using the prescribed SOVT posture; the second group used the vowel /o/; group three used the vowel /a/. The primary outcome measure was MPT as performed on the exercise tasks using the assigned vocal tract posture. RESULT: MPT significantly improved in the prescribed SOVT group, but did not significantly improve in the modified /o/ and /a/ groups. CONCLUSION: The SOVT posture used during VFEs is modifiable to a small extent without significantly undermining efficacy. Changes in MPT are less robust with reduced VT occlusion. Research in a clinical population is warranted.

Vocalization Subsystem Responses to a Temporarily Induced Unilateral Vocal Fold Paralysis.

Purpose: The purpose of this study is to quantify the interactions of the 3 vocalization subsystems of respiration, phonation, and resonance before, during, and after a perturbation to the larynx (temporarily induced unilateral vocal fold paralysis) in 10 vocally healthy participants. Using dynamic systems theory as a guide, we hypothesized that data groupings would emerge revealing context-dependent patterns in the relationships of variables representing the 3 vocalization subsystems. We also hypothesized that group data would mask important individual variability important to understanding the relationships among the vocalization subsystems. Method: A perturbation paradigm was used to obtain respiratory kinematic, aerodynamic, and acoustic formant measures from 10 healthy participants (8 women, 2 men) with normal voices. Group and individual data were analyzed to provide a multilevel analysis of the data. A 3-dimensional state space model was constructed to demonstrate the interactive relationships among the 3 subsystems before, during, and after perturbation. Results: During perturbation, group data revealed that lung volume initiations and terminations were lower, with longer respiratory excursions; airflow rates increased while subglottic pressures were maintained. Acoustic formant measures indicated that the spacing between the upper formants decreased (F3-F5), whereas the spacing between F1 and F2 increased. State space modeling revealed the changing directionality and interactions among the 3 subsystems. Conclusions: Group data alone masked important variability necessary to understand the unique relationships among the 3 subsystems. Multilevel analysis permitted a richer understanding of the individual differences in phonatory regulation and permitted subgroup analysis. Dynamic systems theory may be a useful heuristic to model the interactive relationships among vocalization subsystems. Supplemental Material: https://doi.org/10.23641/asha.5913532.

Effects of ageing on orofacial fine force control and its relationship with parallel change in sensory perception.

PURPOSE: Current theoretical models suggest the importance of a bidirectional relationship between sensation and production in the vocal tract to maintain lifelong speech skills. The purpose of this study was to assess age-related changes in orofacial skilled force production and to begin defining the orofacial perception-action relationship in healthy adults. METHOD: Low-level orofacial force control measures (reaction time, rise time, peak force, mean hold force (N) and force hold SD) were collected from 60 adults (19-84 years). Non-parametric Kruskal Wallis tests were performed to identify statistical differences between force and group demographics. Non-parametric Spearman's rank correlations were completed to compare force measures against previously published sensory data from the same cohort of participants. RESULT: Significant group differences in force control were found for age, sex, speech usage and smoking status. Significant correlational relationships were identified between labial vibrotactile thresholds and several low-level force control measures collected during step and ramp-and-hold conditions. CONCLUSION: These findings demonstrate age-related alterations in orofacial force production. Furthermore, correlational analysis suggests as vibrotactile detection thresholds increase, the ability to maintain low-level force control accuracy decreases. Possible clinical applications and treatment consequences of these findings for speech disorders in the ageing population are provided.

Subcutaneous Neurotrophin 4 Infusion Using Osmotic Pumps or Direct Muscular Injection Enhances Aging Rat Laryngeal Muscles.

Laryngeal dysfunction in the elderly is a major cause of disability, from voice disorders to dysphagia and loss of airway protective reflexes. Few, if any, therapies exist that target age-related laryngeal muscle dysfunction. Neurotrophins are involved in muscle innervation and differentiation of neuromuscular junctions (NMJs). It is thought that neurotrophins enhance neuromuscular transmission by increasing neurotransmitter release. The neuromuscular junctions (NMJs) become smaller and less abundant in aging rat laryngeal muscles, with evidence of functional denervation. We explored the effects of NTF4 for future clinical use as a therapeutic to improve function in aging human laryngeal muscles. Here, we provide the detailed protocol for systemic application and direct injection of NTF4 to investigate the ability of aging rat laryngeal muscle to remodel in response to NTF4 application. In this method, rats either received NTF4 either systemically via osmotic pump or by direct injection through the vocal folds. Laryngeal muscles were then dissected and used for histological examination of morphology and age-related denervation.

Immediate Effects of the Vocal Function Exercises Semi-Occluded Mouth Posture on Glottal Airflow Parameters: A Preliminary Study.

OBJECTIVES: The study aimed to quantify immediate alterations in the airflow glottogram between the Vocal Function Exercises semi-occluded mouth posture (/ol/ with lip buzz) and the sustained vowel /o/ in individuals with normal voices, and to determine if noted changes were in agreement with established semi-occluded vocal tract aerodynamic theory. Based on semi-occluded vocal tract aerodynamic theory, we hypothesized the following immediate changes in the flow glottogram during the /ol-buzz/ condition: a greater open quotient, a greater skewing quotient, a greater maximum flow declination rate, increased average airflow, decreased peak airflow, and increased minimum airflow. METHODS: A cohort of eight men with normal voices produced the sustained vowel /o/ and the Vocal Function Exercises semi-occluded mouth posture (/ol-buzz/). Flow glottograms for both conditions were obtained from the inverse-filtered oral airflow signal via a circumferentially vented pneumotachograph mask. RESULTS: Data revealed that open quotient and minimum airflow rates increased significantly between conditions. All other measures trended in the directions predicted by aerodynamic theory, but were not statistically significant. CONCLUSIONS: The Vocal Function Exercises semi-occluded mouth posture appeared to provide an effective vocal tract semi-occlusion that immediately altered the flow glottogram in accordance with predictions made by computer-modeled aerodynamic theory.

Enhancement of aging rat laryngeal muscles with endogenous growth factor treatment.

Clinical evidence suggests that laryngeal muscle dysfunction is associated with human aging. Studies in animal models have reported morphological changes consistent with denervation in laryngeal muscles with age. Life-long laryngeal muscle activity relies on cytoskeletal integrity and nerve-muscle communication at the neuromuscular junction (NMJ). It is thought that neurotrophins enhance neuromuscular transmission by increasing neurotransmitter release. We hypothesized that treatment with neurotrophin 4 (NTF4) would modify the morphology and functional innervation of aging rat laryngeal muscles. Fifty-six Fischer 344xBrown Norway rats (6- and 30-mo age groups) were used to evaluate to determine if NTF4, given systemically (n = 32) or directly (n = 24), would improve the morphology and functional innervation of aging rat thyroarytenoid muscles. Results demonstrate the ability of rat laryngeal muscles to remodel in response to neurotrophin application. Changes were demonstrated in fiber size, glycolytic capacity, mitochondrial, tyrosine kinase receptors (Trk), NMJ content, and denervation in aging rat thyroarytenoid muscles. This study suggests that growth factors may have therapeutic potential to ameliorate aging-related laryngeal muscle dysfunction.