Faculty Bibliography

OBJECTIVE:Belting is a vocal quality commonly used across contemporary singing genres. Despite its ubiquity, belting production and perception are highly debated. Variable methodologies and terminology used to discuss, teach, and study belting limit our understanding of underlying mechanisms and restrict the development of science-informed voice pedagogy. We systematically examined the published literature on belting to identify commonalities, disagreements, and directions for future research. METHODS:We conducted a scoping review surveying English-language peer-reviewed scientific studies and pedagogical publications on belting in adult singers that were published between January 1978 and November 2025. Data were extracted and grouped into the following categories: perception, acoustics, physiology, and pedagogy. RESULTS:In total, 2018 publications were reviewed. 472 underwent full-text review, and 112 met inclusion criteria, comprising 58 scientific studies and 54 pedagogical publications. Most scientific studies were cross-sectional comparing the same group or population across variable tasks (n = 25), and pedagogical publications were largely expert commentary (n = 32). Perceptually, belting was characterized as having "bright" or "forward" resonance and increased loudness. Acoustic findings included higher first and second formant frequencies, with the first formant tuned to the second harmonic. Physiologically, belting was associated with an elevated laryngeal position, pharyngeal narrowing, closed quotient >50%, high subglottal pressure, and "megaphone" mouth shape. High individual variability was a hallmark of all findings. Terminology was highly variable, with over 100 words and phrases used to describe belting. CONCLUSIONS:High variability of findings suggests that belting is better understood as a family of related vocal behaviors than as a single, homogeneous phenomenon. We propose three tenets for future work: (1) use of objective acoustic and physiological terminology to define belting, (2) inclusion of multiple terminologies where appropriate to reflect the diversity of learning styles and individual physicality, and (3) use of auditory anchors to supplement written definitions and reduce perceptual ambiguity.

OBJECTIVES/HYPOTHESIS/OBJECTIVE:Concurrent chemoradiotherapy (CCRT) is an effective treatment for various head and neck cancers; however, CCRT can result in significant swallowing impairment, presumably due largely to dysfunction of the muscles of swallowing, which are within the field of radiation. This translational study examines the mechanisms underlying CCRT-induced muscle dysfunction using (1) a rat model of CCRT and (2) analysis of archival human specimens. METHODS:131 Sprague Dawley rats were divided into experimental and control groups. Experimental rats received cisplatin and 5-fluorouracil intravenously, followed by 7 Gray radiation daily for 5 days. Rats were further split into three time points: acute (2 weeks), intermediate (5 months), and long-term (10 months), at which time tissue was harvested for analysis. Human samples included preexisting CCRT-treated and age- and sex-matched control muscle samples from head and neck cancer patients. Quantitative analyses of Paired Box Homeotic Gene 7-positive cells (Pax7 in rats; PAX7 in humans), fibrosis, muscle fiber size, and neuromuscular junctions were conducted and compared between groups in both rats and humans. RESULTS:Analysis demonstrated a significant decline in the percent of Pax7/PAX7-positive cells (a marker of muscle stem cells) after CCRT in both rats and humans, increased collagen percent, and decreased muscle percent in rats at 10 months. CCRT was associated with significantly reduced muscle fiber size in human specimens. Neuromuscular junction presence and morphology in rats were not affected. CONCLUSION/CONCLUSIONS:This translational study demonstrates significant alterations in head and neck muscles in both a rat model and human specimens from subjects exposed to CCRT. LEVEL OF EVIDENCE/METHODS:NA.

INTRODUCTION/BACKGROUND:Sustained ventricular vocal fold (VVF) phonation is an uncommon and often uncomfortable method of vocal production. However, among some singers, including metal vocalists, beatboxers, and throat singers, VVF phonation is common and produced without reported discomfort. Although computational studies and qualitative self-reported data suggest increased air pressure and flow are necessary to produce VVF phonation, quantitative in-vivo aerodynamic data is lacking. OBJECTIVE:To determine the aerodynamic differences between modal true vocal fold (TVF) phonation and two VVF phonation styles (Kargyraa throat singing and mixed vocal distortion) in a trained adult male singer METHODS: TVF and both VVF phonation styles were produced at approximately C3 (∼130Hz) while the singer sustained [a], [i], and [u] three times each, repeated the syllables [pa], [pi], and [pu] five times each, spoke the all-voiced sentence "We were away a year ago," and transitioned between phonation styles on sustained vowels. Sound pressure levels, mean airflow, and mean peak air pressure were compared across tasks and styles. RESULTS:Both styles of VVF phonation showed higher airflow than TVF phonation. Mixed distortion demonstrated instances of 4-fold greater transglottal flow while Kargyraa demonstrated instances of 2-fold greater transglottal flow. Additionally, mean peak air pressure was 2-4-fold greater during the repeated syllables for both VVF styles. Intensity was greater by 2-6 dB SPL in all instances of VVF productions. CONCLUSION/CONCLUSIONS:Overall, airflow, pressure, and intensity were greater in all tasks during VVF phonation. These findings suggest that greater airflow and air pressure are used to sustain these styles of phonation. Future studies will seek to confirm these findings across a diverse set of singers with expertise in VVF phonation and address didactic applications of targeting increased airflow for VVF phonation.

OBJECTIVES/OBJECTIVE:Traditionally, disorders of the vocal fold (VF) mucosa and underlying musculature have been regarded as mutually exclusive entities. However, emerging evidence from other organ systems suggests mucosal and muscle compartments engage in reciprocal interactions with functional consequences. We hypothesized that similar crosstalk exists in the VF, whereby fibrotic mucosa influences adjacent muscle. To model this process, we stimulated human VF fibroblasts (HVOX) with TGF-β1, a central mediator of fibrosis, and examined the effects on rat VF myoblasts (rVF-Mbs), as well as reciprocal influences of rVF-Mbs on fibroblasts. METHODS:HVOX fibroblasts were stimulated with 10 ng/mL TGF-β1, and the effects on rVF-Mbs were assessed using conditioned media and co-culture. Myotube formation was evaluated by immunofluorescence, and nuclear localization of Smad2/3 was examined in conditioned media experiments. qRT-PCR quantified transcripts related to myogenic differentiation and Smad2/3 signaling. ALK4/5 inhibition was performed in co-culture to test TGF-β/Smad2/3-signaling pathway involvement. Reciprocal effects were examined by changes in fibrogenic gene expression in HVOX fibroblasts. RESULTS:Both conditioned media and co-culture suppressed myogenic differentiation in rVF-Mbs; increased inhibition was observed in co-culture, as indicated by reduced myotube formation, decreased Myh2 expression, and activation of Smad2/3 signaling. ALK4/5 inhibition abrogated these effects. Differentiating rVF-Mbs attenuated the fibrogenic phenotype of HVOX fibroblasts. CONCLUSIONS:Fibrotic VF mucosal cells can impair myogenic differentiation through TGF-β/Smad2/3-mediated fibroblast-myoblast crosstalk, and myogenic cells may exert reciprocal anti-fibrotic effects. These findings suggest mucosa-muscle interactions may contribute to VF pathology and highlight Smad2/3 as a potential therapeutic target. LEVEL OF EVIDENCE/METHODS:NA STUDY DESIGN: In vitro.

OBJECTIVES/HYPOTHESIS/OBJECTIVE:This study assessed the vocal health of performers returning to full-time performance after the COVID-19 pandemic shutdown and investigated how differences in voice usage, exposure to voice care professionals, and vocal pathology before and during the pandemic contributed to variability in self-perceived and instrumental vocal outcome measures. STUDY DESIGN/METHODS:This was a prospective, case-control observational study conducted at a single outpatient site. METHODS:Twenty-two patients, 11 cases and 11 controls, were enrolled for the study. All participants were full-time singing professionals prior to the COVID-19 pandemic. Cases were recruited from patients presenting to a tertiary care voice center for vocal or pharyngeal complaints. Controls were healthy volunteers recruited from the general population of professional singers in the surrounding metropolitan area. All participants provided responses to the Voice Handicap Index-10, Evaluation of Ability to Sing Easily, and Laryngopharyngeal Measure of Perceived Sensation validated questionnaires as well as a study survey with questions regarding vocal use and history prior to and during the pandemic. All participants underwent instrumental acoustic and videostroboscopic voice evaluations. RESULTS:Cases had poorer outcome measures overall and were more likely to report their voices were worse at study enrollment when compared to their prepandemic perception (P = 0.027). Cases tended to be older and less likely to have pursued alternative employment during the pandemic that involved increased speaking voice use (27% vs 55%), but these differences were not statistically significant. CONCLUSIONS:There was a variable response among performers to the prolonged hiatus from performing during the COVID-19 pandemic. Those with poorer outcomes tended to be older and may have used their voice less during the pandemic. These findings are consistent with detraining periods in the exercise physiology literature and support the construct of treating vocal performers as vocal athletes.

Rapid and precise activation of the laryngeal musculature, particularly the thyroarytenoid (TA), is required for the production of rat ultrasonic vocalizations (USVs). Although the role of the TA in USV production has been established through denervation and excised larynx studies, how TA muscle dysfunction affects USV acoustics remains unknown. This study examined how iatrogenic, transmuscular vocal fold injury influences USV production by comparing acoustic parameters between rats receiving bilateral transmuscular vocal fold injury (including the TA muscle) versus sham surgery. Twenty adult male rats were randomly assigned to injury or sham groups and assessed at 30 or 60 days post-surgery. USVs were recorded at each timepoint (pre- and post-surgery) and analyzed for changes in principal frequency, frequency complexity (standard deviation and sinuosity), power (intensity of the USV), tonality, and duration. Injury significantly decreased USV frequency complexity and reduced the likelihood of producing frequency-modulated vocalizations in both post-surgical time groups. These findings demonstrate that while TA muscle integrity is crucial for frequency modulation, it is not necessary for basic USV production, offering new insights into the biomechanical role of the TA muscle in rat vocalization and laying the groundwork for investigating therapeutic interventions targeting laryngeal muscle function.

PURPOSE/UNASSIGNED:Primary muscle tension dysphonia (pMTD) is a form of vocal hyperfunction with no preexisting tissue trauma to the vocal folds. There are no known structural or neurological causes of pMTD, and there is rarely obvious, confirmatory evidence to reliably diagnose individuals accurately. Furthermore, acoustic and aerodynamic measurements taken during voice assessments vary widely within this population. The purpose of this study was to find subgroups within a sample of pMTD patients based on acoustic and aerodynamic measurements. We use a computational approach to elucidate what has largely been observational in the past. METHOD/UNASSIGNED:-means clustering analysis was conducted. RESULTS/UNASSIGNED:The exploratory factor analysis grouped together variables across patients, which resulted in three principal axes. These three principal axes separately consisted of aperiodicity, fundamental frequency, and aerodynamic measurements. These principal axes explained 44.7% of the total variance. Four clusters of patients were identified across the three principal axes. These were characterized by (a) a high amount of aperiodicity in the voice, (b) lower fundamental frequency values, (c) higher fundamental frequency values, and (d) high aerodynamic values. CONCLUSIONS/UNASSIGNED:The clusters identified in the current study are reliable and moderately separated. Furthermore, these clusters align with previously identified subgroups in related work. The analysis presented here lays the groundwork for additional clustering analyses with new pMTD samples, as well as future work establishing subtype classifications of pMTD.

OBJECTIVE:Previous investigations demonstrated voice changes corresponding to menstrual cycle phases, but few explored longitudinal cycle-to-cycle variations. The aim of this longitudinal case study was to describe changes in acoustics, laryngeal kinematics, vocal effort, and ability to produce high soft phonation in relation to menstrual cycle phases over the course of multiple cycles in a single normally cycling individual. METHODS:Data were obtained from a 34-year-old professional voice user who had self-collected daily videostroboscopy, acoustics, vocal effort rating, and high soft phonation tasks for 394 days. Data were analyzed by cycle phase and across time for all cycles. RESULTS:Cycle length ranged from 24-32 days. All metrics demonstrated high cycle-to-cycle variability (±2 standard deviation or more). Greatest variability was during menses and luteal phases. The fertile window was the least variable and showed decreased glottal area index (GAI), asymmetry quotient, perceived vocal effort, and increased smoothed cepstral peak prominence, consistent with previous literature suggesting "best" voice quality during the periovulatory period. Perceived vocal effort and fundamental frequency were highest during the luteal phase. GAI was lowest during the luteal phase, and higher during estimated day of ovulation, which contradicts previous findings. CONCLUSION/CONCLUSIONS:This case study represents a unique, longitudinal data set demonstrating changes in phonatory characteristics across repeated menstrual cycles. In general, there was increased variability during rapid hormonal changes (menses, luteal phases) and less variability during hormonal stability (fertile window), suggesting that voice changes are sensitive to the rapid hormonal shifts. Future prospective studies should include multiple participants and concurrent hormone-level tracking. LEVEL OF EVIDENCE/METHODS:Level 4.

OBJECTIVES/OBJECTIVE:) and PRO scores; (3) explore how changes across individual PROs align with changes in DIGEST pre- to six weeks post- surgery. METHODS:) pharyngeal total score and the DIGEST. PROs included the Bazaz Dysphagia Scale, the Eating Assessment Tool (EAT-10), the Swallowing Quality of Life Questionnaire (SWAL-QoL), and the Hospital for Special Surgery Dysphagia Index (HSS-DDI). RESULTS:Statistical models for all outcome measures revealed a significant effect of operative timepoint, indicating worse outcomes postoperatively. There were greater postoperative increases in point prevalence and incidence rates using PROs compared with DIGEST. Rates of clinically meaningful change were similar across PROs and DIGEST, but not consistently across the same individual cases. CONCLUSION/CONCLUSIONS:This study highlights the difference between physical function and patient experience, suggesting the presence or absence of dysphagia symptoms may not correspond with observed physical impairments after ACDF. LEVEL OF EVIDENCE/METHODS:Level III.

OBJECTIVES/HYPOTHESIS/OBJECTIVE:To identify vocal tract configuration patterns in vocally healthy contemporary commercial music (CCM) singers during the production of five industry-typical vocal qualities, including various belting qualities and traditional/legit musical theater singing. STUDY DESIGN/METHODS:Prospective, observational study. METHODS:Seven professional musical theater singers (four females, three males) performed arpeggiated patterns using five different vocal qualities: traditional/legit, neutral belt, brassy belt, warm belt, and rock belt. Real-time magnetic resonance imaging captured midsagittal vocal tract configurations. Eight morphological measures were analyzed: lip opening, jaw opening, jaw protrusion, tongue dorsum height, uvula elevation, oropharyngeal opening, laryngeal height, and laryngeal tilt. Linear mixed-effects modeling explored relationships between vocal qualities and anatomical measurements. RESULTS:Lip opening, jaw opening, oropharyngeal opening, and laryngeal height showed significant differences across vocal qualities. The traditional/legit voice quality demonstrated the smallest lip, jaw, and oropharyngeal openings with the lowest laryngeal position. Rock belt showed the largest lip and jaw openings. Brassy belt and rock belt featured larger oropharyngeal space and higher tongue positions than other qualities, creating a "tube-like" shape rather than the previously suggested megaphone shape. Laryngeal positioning was elevated in all belting styles, but not in traditional/legit. No significant differences were found between male and female participants. Lower pitch tasks were characterized by smaller lip, jaw, and oropharyngeal openings compared with higher pitch tasks. CONCLUSION/CONCLUSIONS:This pilot study revealed distinct vocal tract configurations for different vocal qualities, particularly between traditional/legit and belting styles. The findings challenge previous assumptions about megaphone-shaped vocal tracts in belting, demonstrating more complex configurations. These results provide a foundation for identifying typical versus atypical vocal tract adjustments in CCM singing, with implications for voice pedagogy and clinical practice.