The Effects of Menopause on Neuromuscular Parameters of the Rat Vocal Folds
OBJECTIVES/HYPOTHESIS/OBJECTIVE:Menopause adversely affecs power and endurance of the limb muscles. However, despite clinical observations that menopause corresponds to negative changes of the voice, the direct effects of estrogen deprivation on the thyroarytenoid muscles are unknown. The purpose of this study was to investigate the effects of estrogen deprivation via ovariectomy on three neuromuscular parameters of the thyroarytenoid muscles using a rat model. STUDY DESIGN/METHODS:Animal model. METHODS:Cryosections of vocal folds of 20 (10 control and 10 ovariectomized) female rats were stained to label neuromuscular junctions, fiber size, or parvalbumin levels using immunohistochemical techniques and compared between experimental groups. RESULTS:The neuromuscular junctions, thyroarytenoid fiber sizes, and parvalbumin levels of the vocal folds were similar between experimental groups. CONCLUSIONS:The loss of estrogen did not change neuromuscular parameters of the vocal folds of adult female rats; therefore, vocal changes within the outer vibratory layers of the vocal folds may primarily be responsible for clinically observed menopausal vocal changes. LEVEL OF EVIDENCE/METHODS:NA Laryngoscope, 2020.
Metabolomic Expression of Laryngeal and Hindlimb Muscles in Adult versus Senescent Rats
OBJECTIVES/UNASSIGNED:(1) Determine the feasibility of obtaining a global, unbiased metabolomic profile on laryngeal muscle in a rat model; (2) evaluate the impact of biological aging on the laryngeal metabolome; and (3) characterize biochemical expression differences between aged and non-aged laryngeal and hindlimb muscle. METHODS/UNASSIGNED:Thyroarytenoid laryngeal muscle and plantaris hindlimb muscle were harvested from 5 young adult (9â€‰months old) and 5 older adult (32â€‰months old) F344BN rats. Tissue was processed and analyzed using LC-MS methods. Detected metabolites were compared to widely used metabolite databases and KEGG pathway enrichment was performed on significant metabolites. RESULTS/UNASSIGNED:The greatest differences in metabolite expression were between laryngeal and limb muscle with 126 different metabolites found between laryngeal and limb within the young group and 149 different metabolites within the old group. Significant hits between muscle groups highlighted amino acid differences between these tissues. There were more robust differences with age in limb muscle compared to laryngeal muscle. CONCLUSIONS/UNASSIGNED:Amino acid metabolism is a key difference between muscles of the limbs and larynx. Due to the number of differentially expressed metabolites between the 2 muscle groups, caution should be exercised when applying skeletal limb muscle physiology and biology concepts to the vocal muscles in both aged and non-aged musculoskeletal systems. Mechanisms underlying less robust effects of age on laryngeal muscle compared to limb muscle require elucidation.
Exercise Science and the Vocalist
The application of exercise science training knowledge has been of growing interest to voice professionals. This tutorial, derived from the authors' invited presentations from the "Exercise and the Voice" Special Session at the 2018 Voice Foundation Symposium, proposes a foundational theoretical structure based in exercise science, clarifies the wide range of variables that may influence voice training, and summarizes our present understanding of voice physiology from the perspective of muscle training. The body of literature on voice exercise was then analyzed from the perspective of this framework, identifying what we currently know and what we still have yet to learn.
Effects of Vocal Training on Thyroarytenoid Muscle Neuromuscular Junctions and Myofibers in Young and Older Rats
The purpose of this investigation was to determine the effects of vocal training on neuromuscular junction (NMJ) morphology and muscle fiber size and composition in the thyroarytenoid muscle, the primary muscle in the vocal fold, in younger (9-month) and older (24-month) Fischer 344 Ã— Brown Norway male rats. Over 4 or 8 weeks of vocal training, rats of both ages progressively increased their daily number of ultrasonic vocalizations (USVs) through operant conditioning and were then compared to an untrained control group. Neuromuscular junction morphology and myofiber size and composition were measured from the thyroarytenoid muscle. Acoustic analysis of USVs before and after training quantified the functional effect of training. Both 4- and 8-week training resulted in less NMJ motor endplate dispersion in the lateral portion of the thyroarytenoid muscle in rats of both ages. Vocal training and age had no significant effects on laryngeal myofiber size or type. Vocal training resulted in a greater number of USVs with longer duration and increased intensity. This study demonstrated that vocal training induces laryngeal NMJ morphology and acoustic changes. The lack of significant effects of vocal training on muscle fiber type and size suggests vocal training significantly improves neuromuscular efficiency but does not significantly influence muscle strength changes.
The effects of the estrous cycle, menopause, and recording condition on female rat ultrasonic vocalizations
The goal of this study was to evaluate the effects of ovarian hormones on female rat ultrasonic vocalizations (USVs). Twenty (10 control and 10 ovariectomized) 3-month-old female rats were recorded in 3 recording conditions (elicitation, dyad, and isolation) over a full estrous cycle or time-matched duration. There were differences in USV acoustics (frequency and complexity parameters) across recording conditions but no differences in USV acoustics between control and ovariectomized groups. USVs produced in isolation had lower frequency and complexity parameters than elicited USVs for both control and ovariectomized rats. Additionally, for control rats, USV parameters of frequency, complexity, duration, and intensity changed depending on the estrous state. Therefore, although fluctuating hormone levels may influence USV acoustics, this variation can be controlled for by ovariectomizing female rats.
Effects of Historical Recording Technology on Vibrato in Modern-Day Opera Singers
OBJECTIVE:Past literature indicates that vibrato measurements of singers objectively changed (i.e., vibrato rate decreased and vibrato extent increased) from 1900 to the present day; however, historical audio recording technology may distort acoustic measurements of the voice output signal, including vibrato. As such, the listener's perception of historical singing may be influenced by the limitations of historical technology. This study attempts to show how the wax cylinder phonograph system-the oldest form of mass-produced audio recording technology-alters the recorded voice output signal of modern-day singers and, thus, provides an objective lens through which to study the effect(s) of historical audio recording technology on vibrato measurements. METHODS:for female singers, three times into a flat-response omnidirectional microphone and onto an Edison Home Phonograph simultaneously. The middle 1-3 seconds (6-10 vibrato cycles) of each sample was analyzed for vibrato rate, vibrato extent, jitter (ddp), shimmer (dda), and fundamental frequency for each recording condition (wax cylinder phonograph or microphone). Steady-state and frequency-modulating sinewave test signals were also recorded under the multiple recording conditions. RESULTS:Results indicated no significant effect of recording condition on vibrato rate (mean [standard deviation], cylinder: 5.3 Hz [0.5], microphone: 5.3 Hz [0.5]) and no significant difference was found for mean fundamental frequency (cylinder: 389 Hz , microphone: 390 Hz ). A significant main effect of recording condition was found for vibrato extent (cylinder: Â±103 cents , microphone: Â±100 cents ). Additionally, mean jitter (ddp) (cylinder: 1.22% [1.09], microphone: 0.24% [0.12]) and mean shimmer (dda) (cylinder: 9.40% [4.90], microphone: 1.92% [0.94]) were significantly higher for the cylinder recording condition, indicating more cycle-to-cycle variability in the wax cylinder recorded signal. Analysis of test signals revealed similar patterns based on recording condition. DISCUSSION/CONCLUSIONS:This study validates past scholarly inquiry about vibrato measurements as extracted from digitized wax cylinder phonograph recordings by demonstrating that measured vibrato rate remains constant during both recording conditions. In other words, vibrato rate as measured from historical recordings can be viewed as an accurate representation of the historical singer being studied. Furthermore, it suggests that the value of prior vibrato extent measurements from these acoustic recordings may be slightly overestimated from the original voice output signals produced by singers near the beginning of the 20th century (i.e., a narrow vibrato extent might have been numerically smaller on average). Increased jitter and shimmer in the wax cylinder recording conditions may be indicative of nonlinearities in the phonograph recording or playback systems.
BAGLS, a multihospital Benchmark for Automatic Glottis Segmentation
Laryngeal videoendoscopy is one of the main tools in clinical examinations for voice disorders and voice research. Using high-speed videoendoscopy, it is possible to fully capture the vocal fold oscillations, however, processing the recordings typically involves a time-consuming segmentation of the glottal area by trained experts. Even though automatic methods have been proposed and the task is particularly suited for deep learning methods, there are no public datasets and benchmarks available to compare methods and to allow training of generalizing deep learning models. In an international collaboration of researchers from seven institutions from the EU and USA, we have created BAGLS, a large, multihospital dataset of 59,250 high-speed videoendoscopy frames with individually annotated segmentation masks. The frames are based on 640 recordings of healthy and disordered subjects that were recorded with varying technical equipment by numerous clinicians. The BAGLS dataset will allow an objective comparison of glottis segmentation methods and will enable interested researchers to train their own models and compare their methods.
Preparation of the Rat Vocal Fold for Neuromuscular Analyses
The purpose of this tutorial is to describe the preparation of the rat vocal fold for histochemical neuromuscular study. This protocol outlines procedures for rat laryngeal dissection, flash-freezing, and cryosectioning of the vocal folds. This study describes how to cryosection vocal folds in both longitudinal and cross-sectional planes. A novelty of this protocol is the laryngeal tracking during cryosectioning that ensures accurate identification of the intrinsic laryngeal muscles and reduces the chance of tissue loss. Figures demonstrate the progressive cryosectioning in both planes. Twenty-nine rat hemi-larynges were cryosectioned and tracked from the emergence of the thyroid cartilage to the appearance of the first section that included the full vocal fold. The full vocal fold was visualized for all animals in both planes. There was high variability in the distance from the appearance of the thyroid cartilage to the appearance of the full vocal fold in both planes. Weight was not correlated to depth of laryngeal landmarks, suggesting individual variability and other factors related to tissue preparation may be responsible for the high variability in the appearance of landmarks during sectioning. This study details a methodology and presents morphological data for preparing the rat vocal fold for histochemical neuromuscular investigation. Due to high individual variability, laryngeal landmarks should be closely tracked during cryosectioning to prevent oversectioning tissue and tissue loss. The use of a consistent methodology, including adequate tissue preparation and awareness of landmarks within the rat larynx, will assist with consistent results across studies and aid new researchers interested in using the rat vocal fold as a model to investigate laryngeal neuromuscular mechanisms.
Acoustic Comparison of Lower and Higher Belt Ranges in Professional Broadway Actresses
PURPOSE/OBJECTIVE:Current research on the female belt voice has generally been limited to the range of C5, which is not representative of the current requirements on Broadway. Additionally, much belt research uses voice teachers or college students. The goal of this study was to acoustically examine both higher and lower belt ranges in 10 women who have performed belt roles on Broadway during the last decade. METHOD/METHODS:We analyzed the long-term average spectrum of the middle stable portion of three belted pitches, one from a lower, more traditional belt song and two from a higher, more contemporary belt song. The dB levels of the first three peaks in the long-term average spectrum corresponding to the first three harmonics were extracted and compared across tasks. Age, professional roles played on Broadway, and self-perceived belt strategy were obtained via interview to find potential unifying factors in resonance strategies. RESULTS:Overall, the dB level of the peaks closest to the second and third harmonics were higher than the peak close to the fundamental frequency. The difference between peaks was statistically greater in the lower belt compared to both higher belt tasks, indicating these singers relied more on a single harmonic in the lower belt range than the higher belt range. In the higher belt range, there was less variability between peaks. No patterns emerged between resonance strategies and demographic information. CONCLUSIONS:Elite female belters use varying resonance strategies to create commercially viable belt sounds in different belt ranges.
Decreased Tongue Volume Post Radiation
OBJECTIVES/UNASSIGNED:To evaluate volume changes within the tongue post chemoradiation therapy (CRT). STUDY DESIGN/UNASSIGNED:Retrospective review. SETTING/UNASSIGNED:Academic Medical Center. SUBJECTS AND METHODS/UNASSIGNED:Subjects included 19 patients that received CRT as the primary treatment for tonsillar or hypopharynx squamous cell carcinoma. Tongue volumes were calculated by three raters from thin slice computed tomography images collected before treatment and up to 29â€‰months post-CRT. Body mass index (BMI) was also collected at each time point. RESULTS/UNASSIGNED:â€‰<â€‰.001) decreased by 0.11â€‰units (SEMâ€‰=â€‰0.02) per month post radiation. CONCLUSION/UNASSIGNED:Tongue dysfunction and decreased tongue strength are significant contributors to the dysphagia that patients experience after receiving CRT. In this study, both tongue volume and BMI decreased post-CRT; therefore, BMI could potentially be used as a predictor of tongue volume post-CRT.