Impact of naturalistic smartphone positioning on acoustic measures of voicea).

Smartphone technology has been used for at-home health monitoring, but there are few available applications (apps) for tracking acoustic measures of voice for those with chronic voice problems. Current apps limit the user by restricting the range of smartphone positions to those that are unnatural and non-interactive. Therefore, we aimed to understand how more natural smartphone positions impacted the accuracy of acoustic measures in comparison to clinically acquired and derived measures. Fifty-six adults (11 vocally healthy, 45 voice disordered, aged 18-80 years) completed voice recordings while holding their smartphones in four different positions (e.g., as if reading from the phone, up to the ear, etc.) while a head-mounted high-quality microphone attached to a handheld acoustic recorder simultaneously captured voice recordings. Comparisons revealed that mean fundamental frequency (Hz), maximum phonation time (s), and cepstral peak prominence (CPP; dB) were not impacted by phone position; however, CPP was significantly lower on smartphone recordings than handheld recordings. Spectral measures (low-to-high spectral ratio, harmonics-to-noise ratio) were impacted by the phone position and the recording device. These results indicate that more natural phone positions can be used to capture specific voice measures, but not all are directly comparable to clinically derived values.

The relationship between acoustical and perceptual measures of vocal effort.

Excessive vocal effort is a common clinical voice symptom, yet the acoustical manifestation of vocal effort and how that is perceived by speakers and listeners has not been fully elucidated. Here, 26 vocally healthy adults increased vocal effort during the production of the utterance /ifi/, followed by self-ratings of effort on a 100 mm visual analog scale. Twenty inexperienced listeners assessed the speakers' vocal effort using the visual sort-and-rate method. Previously proposed acoustical correlates of vocal effort were calculated, including: mean sound pressure level (SPL), mean fundamental frequency (f o), relative fundamental frequency (RFF) offset cycle 10 and onset cycle 1, harmonics-to-noise ratio (HNR), cepstral peak prominence and its standard deviation (SD), and low-to-high (L/H) spectral ratio and its SD. Two separate mixed-effects regression models yielded mean SPL, L/H ratio, and HNR as significant predictors of both speaker and listener ratings of vocal effort. RFF offset cycle 10 and mean f o were significant predictors of listener ratings only. Therefore, speakers and listeners attended to similar acoustical cues when making judgments of vocal effort, but listeners also used additional time-based information. Further work is needed to determine how vocal effort manifests in the speech signal in speakers with voice disorders.

A Scoping Review on the Intersection Between Voice and Swallowing Measures in Healthy and Disordered Populations.

PURPOSE: Voice and swallowing are distinct functions that share anatomical and physiological properties; however, research investigating their intersection is limited. The purpose of this scoping review was to explore the literature surrounding the relationship between voice and swallowing measures in healthy adults and those with non-degenerative disorders. Specifically, we aimed to elucidate whether objective voice measures could be used as correlates of swallowing function. METHOD: We systematically searched four databases (Embase, PubMed, CINAHL, and Web of Science) for relevant literature using a combination of key words and controlled vocabulary generated from the Yale Mesh Analyzer. The inclusion criteria consisted of peer-reviewed studies in the English language that reported on healthy adults and/or patients with non-degenerative neurological disorders and pulmonary diseases and contained instrumental and/or objective voice and swallowing measures. Two raters completed the abstract screening process followed by independent full-text reviews. Case studies, review studies, gray literature, or abstract-only studies were excluded. RESULTS: Among 5,485 screened studies, 182 were fully reviewed, with only 11 studies meeting the inclusion criteria. Eight studies found an association between voice and swallowing objective measures, whereas the other three did not. Significant voice measures that were related to swallowing safety and/or physiology included maximum fundamental frequency (F0), F0 range, maximum phonation time, biomechanics of effortful pitch glides, and voice onset time. CONCLUSIONS: Although there was heterogeneity in the measures used, specific objective voice measures showed promise in clinical practice as a screening tool for dysphagia. Further investigations are needed to validate the clinical utility of these measures across diverse patient populations.

Gender-Diverse Patients' Awareness and Utilization of Gender-Affirming Laryngological Services.

OBJECTIVE: Despite gender-affirming laryngological services (GALS; eg, voice therapy or surgery) being available nationwide, there is a discrepancy between the number of transgender and gender diverse (TGD) people with vocal incongruence and those who pursue services. Primary care is an important setting for accessing gender-affirming care, including learning about GALS. The purpose of this study was to understand the relationship between access to primary care and utilization of GALS. METHODS: An anonymous cross-sectional online survey was developed in REDCap. Between June-November 2022, 187 TGD respondents answered all questions related to this analysis. We assessed the relationship between having a primary care provider (PCP) and use of GALS via logistic regression. RESULTS: Of the 167 individuals who reported having a PCP, 54% reported familiarity with GALS, compared to 45% of individuals without a PCP. Compared to the group without a PCP, a greater proportion of individuals with a PCP had received professional voice therapy (21% vs 5%) and voice surgery (3% vs 0%). Logistic regression models did not demonstrate a significant effect of primary care access on either familiarity with, or use of, GALS. CONCLUSION: Most respondents (89%) were linked to the medical community through a PCP. A greater proportion of respondents with a PCP had accessed professional voice therapy and voice surgery compared with respondents without a PCP, though this difference was not statistically significant. Increased communication between GALS providers and PCPs would raise awareness of available services and may strengthen the referral pipeline to increase access to vocal care. LEVEL OF EVIDENCE: Level III.

Reducing Vocal Fatigue While Preserving Realism During Video Game Voice-Overs Using the Vocal Combat Technique: A Randomized Controlled Trial.

OBJECTIVE: Vocal Combat Technique (VCT) teaches indirect and direct behavioral voice techniques to voice-over artists performing in violent video games. Although previous work on VCT has shown promise for mitigating dysphonia symptoms, a randomized clinical trial has yet to be undertaken. Therefore, we completed a randomized, controlled trial between a group of experienced video game voice-over actors receiving VCT and a control group comparison. METHODS: A total of 24 video game voice-over actors completed this study. Participants were randomly assigned to receive VCT or indirect vocal hygiene training prior to completing an intensive 1-hour video game voice recording session. The primary outcome was a change in Voice Handicap Index-10 (VHI-10) preperformance/postperformance. Secondary measures included a modified version of the Evaluation of the Ability to Sing Easily (m-EASE), the Vocal Tract Discomfort Scale (VTDS), and questions regarding return to work. Participants were also rated on the realism of their vocal performance by a blinded video game director. RESULTS: The VCT group showed a significantly smaller change in VHI-10 and m-EASE scores postperformance, and a higher increased likelihood to return to work compared to the control group. There were no group differences for VTDS or realism ratings. Four participants from the control group exhibited outlier behavior with more pronounced phonotraumatic symptoms following performance than all other participants. CONCLUSIONS: VCT shows evidence of mitigating symptoms of dysphonia while preserving the realism of the vocal performance. More work is needed to understand performers at risk for more severe vocal symptoms following extreme voice-over work, so as to target them for preventative techniques and voice preservation.

Voice Acoustics and Vocal Effort in Mask-Wearing Healthcare Professionals: A Comparison Pre- and Post-Workday.

OBJECTIVE: We evaluated voice acoustics and self-perceptual ratings in healthcare workers required to wear face masks throughout their workday. METHODS: Eighteen subjects (11 cisgender female, 7 cisgender male; M = 33.72 years, SD = 8.30) completed self-perceptual ratings and acoustic recordings before and after a typical workday. Chosen measures were specific to vocal effort, dysphonia, and laryngeal tension. Mixed effects models were calculated to determine the impact of session, mask type, sex, and their interactions on the set of perceptual and acoustic measures. RESULTS: The subjects self-reported a significant increase in vocal effort following the workday. These perceptual changes coincided with an increase in vocal intensity and harmonics-to-noise ratio, but decrease in relative fundamental frequency offset 10. As expected, men and women differed in measures related to fundamental frequency and vocal tract length. CONCLUSION: Healthcare professionals wearing masks reported greater vocal symptoms post-workday compared to pre-workday. These symptoms coincided with acoustic changes previously related to vocal effort; however, the degree of change was considered mild. Further research is needed to determine whether vocal hygiene strategies may reduce vocal symptoms in mask-wearing workers.

Characterizing Speech Sound Productions in Bilingual Speakers of Jamaican Creole and English: Application of Durational Acoustic Methods.

PURPOSE: This study examined the speech acoustic characteristics of Jamaican Creole (JC) and English in bilingual preschoolers and adults using acoustic duration measures. The aims were to determine if, for JC and English, (a) child and adult acoustic duration characteristics differ, (b) differences occur in preschoolers' duration patterns based on the language spoken, and (c) relationships exist between the preschoolers' personal contextual factors (i.e., age, sex, and percentage of language [%language] exposure and use) and acoustic duration. METHOD: Data for this cross-sectional study were collected in Kingston, Jamaica, and New York City, New York, United States, during 2013-2019. Participants included typically developing simultaneous bilingual preschoolers (n = 120, ages 3;4-5;11 [years;months]) and adults (n = 15, ages 19;0-54;4) from the same linguistic community. Audio recordings of single-word productions of JC and English were collected through elicited picture-based tasks and used for acoustic analysis. Durational features (voice onset time [VOT], vowel duration, whole-word duration, and the proportion of vowel to whole-word duration) were measured using Praat, a speech analysis software program. RESULTS: JC-English-speaking children demonstrated developing speech motor control through differences in durational patterns compared with adults, including VOT for voiced plosives. Children's VOT, vowel duration, and whole-word duration were produced similarly across JC and English. The contextual factor %language use was predictive of vowel and whole-word duration in English. CONCLUSIONS: The findings from this study contribute to a foundation of understanding typical bilingual speech characteristics and motor development as well as schema in JC-English speakers. In particular, minimal acoustic duration differences were observed across the post-Creole continuum, a feature that may be attributed to the JC-English bilingual environment. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.21760469.

Comparison Between Custom Smartphone Acoustic Processing Algorithms and Praat in Healthy and Disordered Voices.

OBJECTIVE: The aim of this study was to understand the relationship between temporal and spectral-based acoustic measures derived using Praat and custom smartphone algorithms across patients with a wide range of vocal pathologies. METHODS: Voice samples were collected from 56 adults (11 vocally healthy, 45 dysphonic, aged 18-80 years) performing three speech tasks: (a) sustained vowel, (b) maximum phonation, and (c) the second and third sentences of the Rainbow passage. Data were analyzed to extract mean fundamental frequency (fo), maximum phonation time (MPT), and cepstral peak prominence (CPP) using Praat and our custom smartphone algorithms. Linear regression models were calculated with and without outliers to determine relationships. RESULTS: Statistically significant relationships were found between the smartphone algorithms and Praat for all three measures (r2 = 0.68-0.95, with outliers; r2 = 0.80-0.98, without outliers). An offset between CPP measures was found where Praat values were consistently lower than those computed by the smartphone app. Outlying data were identified and described, and findings indicated that speakers with high levels of clinician-perceived dysphonia resulted in smartphone algorithm errors. CONCLUSIONS: These results suggest that the proposed algorithms can provide measurements comparable to clinically derived values. However, clinicians should take caution when analyzing severely dysphonic voices as the current algorithms show reduced accuracy for measures of mean fo and MPT for these voice types.

Factors Related to Treatment Attendance for Patients Seeking Gender-Affirming Voice Therapy.

OBJECTIVE: The purpose of this study was to investigate factors related to treatment attendance for patients seeking gender-affirming voice therapy (GAVT). METHOD: We completed retrospective chart reviews of 50 patients (43 transgender women, three transgender men, four nonbinary patients; aged 18-67 years, M = 34.92 years, SD = 12.32 years) referred for GAVT at a Midwest outpatient center from 2016 to 2021. Data extraction included patient demographics, therapy visit specifics (e.g., number of sessions attended, treatment completion status, and in-person vs. virtual visits) and treatment timing (in relation to the onset of the COVID-19 pandemic), and psychosocial and socioeconomic information. RESULTS: There was no impact of treatment-timing relative to the onset of the pandemic on any attendance measure; however, patients were 1.9 times more likely to complete therapy with each virtual telehealth session attended. Individual factors of outside social support and hormone replacement therapy were positively related to the number of therapy sessions attended, whereas insurance provider and employment status were related to therapy completion. CONCLUSIONS: Telehealth attendance during the COVID-19 pandemic was positively associated with GAVT completion. Future research should investigate psychosocial and socioeconomic factors to understand how to identify patients at risk for poor treatment adherence and facilitate access to clinical care.

Mitigating Dysphonia, Pain, and Vocal Handicap after Violent Video Game Voice Overs: A Pilot Investigation into Vocal Combat Technique Training.

OBJECTIVE: to investigate how the Vocal Combat Technique (VCT) may mitigate vocal symptoms in voice over actors using vocal violence. METHODS: Five voice over actors (3 male, 2 females, Mean = 29.6 years) completed two study sessions of 45 minutes-to-1 hour of vocally violent voice over work held approximately 4 weeks apart. During session one, participants completed voice over work as they typically would, whereas they received 3-hours of VCT training to improve/assist in healthy vocal techniques prior to session two. Pre- and post-session measures for both sessions included self-perceptual ratings of vocal symptoms, auditory-perceptual evaluation, and traditional acoustic measures of frequency and perturbation. RESULTS: Participants showed substantial mitigating effects of VCT training on acoustic perturbation measures (jitter, shimmer, harmonics-to-noise ratio), and self-ratings of vocal symptoms (Vocal-Handicap Index-10, McGill Pain Scale for vocal discomfort, and Evaluation of the Ability to Sing Easily) with calculated medium to large effect sizes (d = 0.61-1.95). There were no changes in auditory perceptual ratings across sessions. CONCLUSION: Our pilot investigation yielded positive improvements in vocal symptomology in five voice over actors who were trained in VCT. Next steps should include a larger enrollment of voice actors to determine optimal preventative and recovery techniques.

Linguistically Informed Acoustic and Perceptual Analysis of Bilingual Children's Speech Productions: An Exploratory Study in the Jamaican Context.

PURPOSE: The aim of this study was to characterize speech acoustics in bilingual preschoolers who speak Jamaican Creole (JC) and English. We compared a standard approach with a culturally responsive approach for characterizing speech sound productions. Preschoolers' speech productions were compared to adult models from the same linguistic community as a means for providing confirmatory evidence of typical speech patterns specific to JC-English speakers. METHOD: Two protocols were applied to the data collected using the Diagnostic Evaluation of Articulation and Phonology (DEAP) Articulation subtest: (a) the standardized DEAP protocol and (b) a culturally and linguistically adapted protocol reflective of the Jamaican post-Creole (English to Creole) continuum. The protocols were used to analyze responses from JC-English-speaking preschoolers (n = 119) and adults (n = 15). Responses were analyzed using acoustic (voice onset time, whole-word duration, and vowel duration) and perceptual (percentage of consonant correct-revised and response frequencies) measures. RESULTS: The culturally responsive protocol captured variation in the frequency and acoustic differences produced in the post-Creole continuum, with higher amounts of "other" responses compared to "standard" target responses for both children and adults. Adults' whole-word durations were shorter and showed more consistent prevoicing during initial plosives compared to the children. CONCLUSIONS: Applying culturally responsive methods, including knowledge of the variation produced in the post-Creole continuum and with adult models from the same linguistic community, improved the ecological validity of speech characterizations for JC-English preschoolers. Acoustic properties of speech should be investigated further as a means of describing bilingual development and distinguishing between difference and disorder. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.20249382.

Impact of Face Masks on Speech Acoustics and Vocal Effort in Healthcare Professionals.

OBJECTIVES/HYPOTHESIS: We investigated speech acoustics and self-reported vocal symptoms in mask-wearing healthcare professionals. We hypothesized that there would be an attenuation of spectral energies and increase in vocal effort during masked speech compared to unmasked speech. STUDY DESIGN: Within and between subject quasi-experimental design. METHODS: We prospectively enrolled 21 healthcare providers (13 cisgender female, 8 cisgender male; M = 32.9 years; SD = 7.9 years) and assessed acoustics and perceptual measures with and without a face mask in place. Measurements included: 1) acoustic Vowel Articulation Index (VAI); 2) cepstral and spectral acoustic measures; 3) traditional vocal measures (e.g., fundamental frequency, intensity); 4) relative fundamental frequency (RFF); and 5) self-reported ratings of vocal effort and dyspnea. RESULTS: During masked speech, there was a significant reduction in VAI, high-frequency information (>4 kHz), and RFF offset 10, as well as a significant increase in cepstral peak prominence and perceived vocal effort. Further analysis showed that high-frequency attenuation was more pronounced when wearing an N95 mask compared to a simple mask. CONCLUSIONS: Face masks pose an additional barrier to effective communication that primarily impacts spectral characteristics, vowel space measures, and vocal effort. Future work should evaluate how long-term mask use impacts vocal health and may contribute to vocal problems. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:391-397, 2022.

Developing Educational Health Modules to Improve Vocal Wellness in Mask-Wearing Occupational Voice Users.

OBJECTIVE: To develop educational modules to improve vocal wellness and optimize communication in mask-wearing occupational voice users. METHODS: Module development focused on identifying accurate, understandable, and actionable steps to improve vocal wellness in the workplace. We i) interviewed eight voice-specialized speech-language pathologists and researchers on current speech and voice recommendations for mask-wearers, ii) developed educational content using the standardized Patient Education Materials Assessment Tool (PEMAT), iii) assessed the ability of nine mask-wearing community members to learn educational content, and iv) compared behavioral, acoustical, and perceptual changes in four mask-wearing healthcare professionals following educational training. RESULTS: We created three educational modules that described key vocal health and communication strategies, including microphone amplification, postural alignment, clear speech, hydration, vocal naps, and vocal warm-ups. PEMAT scores were 96% and 93% on understandability and actionability, respectively. Mask-wearing healthcare professionals increased use of 4 out of the 6 strategies following educational training and were able to retain information at rates >90% at 1-week follow-up. CONCLUSIONS: We developed a set of free-to-use educational modules to promote vocal wellness among mask-wearing occupational voice users (see VSMechLab.com). Future work should examine the impact of these strategies on voice measures in a larger group of mask-wearing community members.

Acoustic Identification of the Voicing Boundary during Intervocalic Offsets and Onsets based on Vocal Fold Vibratory Measures.

Methods for automating relative fundamental frequency (RFF)-an acoustic estimate of laryngeal tension-rely on manual identification of voiced/unvoiced boundaries from acoustic signals. This study determined the effect of incorporating features derived from vocal fold vibratory transitions for acoustic boundary detection. Simultaneous microphone and flexible nasendoscope recordings were collected from adults with typical voices (N=69) and with voices characterized by excessive laryngeal tension (N=53) producing voiced-unvoiced-voiced utterances. Acoustic features that coincided with vocal fold vibratory transitions were identified and incorporated into an automated RFF algorithm ("aRFF-APH"). Voiced/unvoiced boundary detection accuracy was compared between the aRFF-APH algorithm, a recently published version of the automated RFF algorithm ("aRFF-AP"), and gold-standard, manual RFF estimation. Chi-square tests were performed to characterize differences in boundary cycle identification accuracy among the three RFF estimation methods. Voiced/unvoiced boundary detection accuracy significantly differed by RFF estimation method for voicing offsets and onsets. Of 7721 productions, 76.0% of boundaries were accurately identified via the aRFF-APH algorithm, compared to 70.3% with the aRFF-AP algorithm and 20.4% with manual estimation. Incorporating acoustic features that corresponded with voiced/unvoiced boundaries led to improvements in boundary detection accuracy that surpassed the gold-standard method for calculating RFF.

Formant-Estimated Vocal Tract Length and Extrinsic Laryngeal Muscle Activation During Modulation of Vocal Effort in Healthy Speakers.

Purpose The goal of this study was to explore the relationships among vocal effort, extrinsic laryngeal muscle activity, and vocal tract length (VTL) within healthy speakers. We hypothesized that increased vocal effort would result in increased suprahyoid muscle activation and decreased VTL, as previously observed in individuals with vocal hyperfunction. Method Twenty-eight healthy speakers of American English produced vowel-consonant-vowel utterances under varying levels of vocal effort. VTL was estimated from the vowel formants. Three surface electromyography sensors measured the activation of the suprahyoid and infrahyoid muscle groups. A general linear model was used to investigate the effects of vocal effort level and surface electromyography on VTL. Two additional general linear models were used to investigate the effects of vocal effort on suprahyoid and infrahyoid muscle activities. Results Neither vocal effort nor extrinsic muscle activity showed significant effects on VTL; however, the degree of extrinsic muscle activity of both suprahyoid and infrahyoid muscle groups increased with increases in vocal effort. Conclusion Increasing vocal effort resulted in increased activation of both suprahyoid and infrahyoid musculature in healthy adults, with no change to VTL.

Longitudinal Case Study of Transgender Voice Changes Under Testosterone Hormone Therapy.

The purpose of this study was to comprehensively evaluate voice and speech changes in one healthy 30-year-old transgender male undergoing testosterone therapy for transition. Testing occurred at three timepoints before cross-sex hormone therapy and every 2 weeks thereafter for 1 year. Data collected included measures of acoustics, aerodynamics, and laryngeal structure and function via flexible laryngoscopy. Analysis included acoustic correlates of pitch, loudness, voice quality, and vocal tract length, as well as perceptual measures of voice quality and gender. Speaking fundamental frequency (fo) lowered from 183 Hz to 134 Hz. Phonatory frequency range (ie, minimum and maximum singing range) shifted from a range of D#3-E6 to a range of A2-A5. Perceptual measures of voice quality indicated no negative changes. Naïve listeners reliably rated the participant's speech samples as male after 37 weeks on testosterone. Few studies document in detail the variety of voice changes that occur during cross-sex hormone therapy, focusing instead on fo alone. This study adds to the literature a comprehensive case study of speech and voice changes experienced by one transmasculine participant undergoing testosterone therapy.

Voice Onset Time in Individuals With Hyperfunctional Voice Disorders: Evidence for Disordered Vocal Motor Control.

Purpose This study examined vocal hyperfunction (VH) using voice onset time (VOT). We hypothesized that speakers with VH would produce shorter VOTs, indicating increased laryngeal tension, and more variable VOTs, indicating disordered vocal motor control. Method We enrolled 32 adult women with VH (aged 20-74 years) and 32 age- and sex-matched controls. All were speakers of American English. Participants produced vowel-consonant-vowel combinations that varied by vowel (ɑ/u) and plosive (p/b, t/d, k/g). VOT-measured at the release of the plosive to the initiation of voicing-was averaged over three repetitions of each vowel-consonant-vowel combination. The coefficient of variation (CoV), a measure of VOT variability, was also computed for each combination. Results The mean VOTs were not significantly different between the two groups; however, the CoVs were significantly greater in speakers with VH compared to controls. Voiceless CoV values were moderately correlated with clinical ratings of dysphonia (r = .58) in speakers with VH. Conclusion Speakers with VH exhibited greater variability in phonemic voicing targets compared to vocally healthy speakers, supporting the hypothesis for disordered vocal motor control in VH. We suggest future work incorporate VOT measures when assessing auditory discrimination and auditory-motor integration deficits in VH.

The Accuracy of Respiratory Calibration Methods for Estimating Lung Volume During Speech Breathing: A Comparison of Four Methods Across Three Adult Cohorts.

Purpose This study evaluated the accuracy of respiratory calibration methods for estimating lung volume during speech breathing. Method Respiratory kinematic data were acquired via inductance plethysmography in 32 young adults, 22 older adults, and 13 older adults with Parkinson's disease (PD). Raw rib cage (RC) and abdomen (AB) signals (V) were calibrated to liters using 4 correction methods: (a) isovolume maneuvers, (b) a constant 2:1 RC-to-AB ratio, (c) least squares method with RC correction only (LsqRC), and (d) least squares method with both RC and AB corrections (LsqRC/AB). Mean percent error, the absolute difference between estimated and actual lung volumes then normalized to each speaker's vital capacity, was calculated for each method. Results For young adults, the LsqRC/AB method significantly reduced mean percent error compared to all other methods. Although LsqRC/AB also resulted in smaller errors for older adults and adults with PD, LsqRC/AB and LsqRC were not significantly different from one another in these groups. Conclusion The LsqRC/AB method reduces errors across all cohorts, but older adults and adults with PD also have reduced errors when using LsqRC. Further research should investigate both least squares methods across larger age and disease severity ranges.

Adductory Vocal Fold Kinematic Trajectories During Conventional Versus High-Speed Videoendoscopy.

Objective Prephonatory vocal fold angle trajectories may supply useful information about the laryngeal system but were examined in previous studies using sigmoidal curves fit to data collected at 30 frames per second (fps). Here, high-speed videoendoscopy (HSV) was used to investigate the impacts of video frame rate and sigmoidal fitting strategy on vocal fold adductory patterns for voicing onsets. Method Twenty-five participants with healthy voices performed /ifi/ sequences under flexible nasendoscopy at 1,000 fps. Glottic angles were extracted during adduction for voicing onset; resulting vocal fold trajectories (i.e., changes in glottic angle over time) were down-sampled to simulate different frame rate conditions (30-1,000 fps). Vocal fold adduction data were fit with asymmetric sigmoids using 5 fitting strategies with varying parameter restrictions. Adduction trajectories and maximum adduction velocities were compared between the fits and the actual HSV data. Adduction trajectory errors between HSV data and fits were evaluated using root-mean-square error and maximum angular velocity error. Results Simulated data were generally well fit by sigmoid models; however, when compared to the actual 1,000-fps data, sigmoid fits were found to overestimate maximum angle velocities. Errors decreased as frame rate increased, reaching a plateau by 120 fps. Conclusion In healthy adults, vocal fold kinematic behavior during adduction is generally sigmoidal, although such fits can produce substantial errors when data are acquired at frame rates lower than 120 fps.

The Relationship Between Physiological Mechanisms and the Self-Perception of Vocal Effort.

Purpose This study aimed to examine the relationship between a large set of hypothesized physiological measures of vocal effort and self-ratings of vocal effort. Method Twenty-six healthy adults modulated speech rate and vocal effort during repetitions of the utterance /ifi/, followed by self-perceptual ratings of vocal effort on a visual analog scale. Physiological measures included (a) intrinsic laryngeal tension via kinematic stiffness ratios determined from high-speed laryngoscopy, (b) extrinsic suprahyoid and infrahyoid laryngeal tension via normalized percent activations and durations derived from surface electromyography, (c) supraglottal compression via expert visual-perceptual ratings, and (d) subglottal pressure via magnitude of neck surface vibrations from an accelerometer signal. Results Individual statistical models revealed that all of the physiological predictors, except for kinematic stiffness ratios, were significantly predictive of self-ratings of vocal effort. However, a combined regression model analysis yielded only 3 significant predictors: subglottal pressure, mediolateral supraglottal compression, and the normalized percent activation of the suprahyoid muscles (adjusted R 2 = .60). Conclusions Vocal effort manifests as increases in specific laryngeal physiological measures. Further work is needed to examine these measures in combination with other contributing factors, as well as in speakers with dysphonia.