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

Vowel onset measures and their reliability, sensitivity and specificity: A systematic literature review

OBJECTIVE

To systematically evaluate the evidence for the reliability, sensitivity and specificity of existing measures of vowel-initial voice onset.

METHODS

A literature search was conducted across electronic databases for published studies (MEDLINE, EMBASE, Scopus, Web of Science, CINAHL, PubMed Central, IEEE Xplore) and grey literature (ProQuest for unpublished dissertations) measuring vowel onset. Eligibility criteria included research of any study design type or context focused on measuring human voice onset on an initial vowel. Two independent reviewers were involved at each stage of title and abstract screening, data extraction and analysis. Data extracted included measures used, their reliability, sensitivity and specificity. Risk of bias and certainty of evidence was assessed using GRADE as the data of interest was extracted.

RESULTS

The search retrieved 6,983 records. Titles and abstracts were screened against the inclusion criteria by two independent reviewers, with a third reviewer responsible for conflict resolution. Thirty-five papers were included in the review, which identified five categories of voice onset measurement: auditory perceptual, acoustic, aerodynamic, physiological and visual imaging. Reliability was explored in 14 papers with varied reliability ratings, while sensitivity was rarely assessed, and no assessment of specificity was conducted across any of the included records. Certainty of evidence ranged from very low to moderate with high variability in methodology and voice onset measures used.

CONCLUSIONS

A range of vowel-initial voice onset measurements have been applied throughout the literature, however, there is a lack of evidence regarding their sensitivity, specificity and reliability in the detection and discrimination of voice onset types. Heterogeneity in study populations and methods used preclude conclusions on the most valid measures. There is a clear need for standardisation of research methodology, and for future studies to examine the practicality of these measures in research and clinical settings.

Optical Flow Analysis of Paralaryngeal Muscle Movement

OBJECTIVES

The paralaryngeal muscles are thought to be hyperfunctional with phonation in patients with primary muscle tension dysphonia (pMTD). However, objective, quantitative tools to assess paralaryngeal movement patterns lack. The objectives of this study were to (1) validate the use of optical flow to characterize paralaryngeal movement patterns with phonation, (2) characterize phonatory optical flow velocities and variability of the paralaryngeal muscles before and after a vocal load challenge, and (3) compare phonatory optical flow measures to standard laryngoscopic, acoustic, and self-perceptual assessments.

METHODS

Phonatory movement velocities and variability of the paralaryngeal muscles at vocal onsets and offsets were quantified from ultrasound videos and optical flow methods across 42 subjects with and without a diagnosis of pMTD, before and after a vocal load challenge. Severity of laryngoscopic mediolateral supraglottic compression, acoustic perturbation, and ratings of vocal effort and discomfort were also obtained at both time points.

RESULTS

There were no significant differences in optical flow measures of the paralaryngeal muscles with phonation between patients with pMTD and controls. Patients with pMTD had significantly more supraglottic compression, higher acoustic perturbations, and higher vocal effort and vocal tract discomfort ratings. Vocal load had a significant effect on vocal effort and discomfort but not on supraglottic compression, acoustics, or optical flow measures of the paralaryngeal muscles.

CONCLUSION

Optical flow methods can be used to study paralaryngeal muscle movement velocity and variability patterns during vocal productions, although the role of the paralaryngeal in pMTD diagnostics (e.g., vocal hyperfunction) remains suspect.

LEVEL OF EVIDENCE

2 Laryngoscope, 134:1792-1801, 2024.

Phonemic and pitch variability in bilingual preschoolers: A comparison of Jamaican Creole and English

PURPOSE

The purpose of this study was to investigate the cross-linguistic influences of Jamaican Creole (JC) and English on phonemic and vocal development in bilingual JC-English-speaking preschoolers.

METHOD

Sixteen typically developing children (12 females, M = 4 years; 4 months) completed the Diagnostic Evaluation of Articulation in Phonology Word Inconsistency Assessment subtest in JC and in English. Acoustic measures of voice onset time (VOT), VOT variability (VOT SD), mean fundamental frequency (fo), and fo variability (fo SD) were extracted from each target word. Prevoicing was noted. Mixed models and regression models were analysed to understand the patterns of acoustic measures in each language, and the relationship between phonemic and vocal variability, respectively.

RESULT

Analyses showed a significant effect of language on fo SD, wherein SD was greater in English than JC. JC spoken (percentage) was a significant positive predictor of VOT SD for voiced (short lag) productions. There was no relationship between phonemic and vocal variability measures.

CONCLUSION

Greater fo SD in English may be due to linguistic fo differences and speaking environment. Variability for voiced VOT is likely due to the continued maturation of vocal and articulatory control when children are developing adult-like productions, though longitudinal studies are needed.

Characterization of Primary Muscle Tension Dysphonia Using Acoustic and Aerodynamic Voice Metrics

OBJECTIVES/HYPOTHESIS

The objectives of this study were to (1) identify optimal clusters of 15 standard acoustic and aerodynamic voice metrics recommended by the American Speech-Language-Hearing Association (ASHA) to improve characterization of patients with primary muscle tension dysphonia (pMTD) and (2) identify combinations of these 15 metrics that could differentiate pMTD from other types of voice disorders.

STUDY DESIGN

Retrospective multiparametric METHODS: Random forest modeling, independent t-tests, logistic regression, and affinity propagation clustering were implemented on a retrospective dataset of 15 acoustic and aerodynamic metrics.

RESULTS

Ten percent of patients seen at the New York University (NYU) Voice Center over two years met the study criteria for pMTD (92 out of 983 patients), with 65 patients with pMTD and 701 of non-pMTD patients with complete data across all 15 acoustic and aerodynamic voice metrics. PCA plots and affinity propagation clustering demonstrated substantial overlap between the two groups on these parameters. The highest ranked parameters by level of importance with random forest models-(1) mean airflow during voicing (L/sec), (2) mean SPL during voicing (dB), (3) mean peak air pressure (cmH2O), (4) highest F0 (Hz), and (5) CPP mean vowel (dB)-accounted for only 65% of variance. T-tests showed three of these parameters-(1) CPP mean vowel (dB), (2) highest F0 (Hz), and (3) mean peak air pressure (cmH2O)-were statistically significant; however, the log2-fold change for each parameter was minimal.

CONCLUSION

Computational models and multivariate statistical testing on 15 acoustic and aerodynamic voice metrics were unable to adequately characterize pMTD and determine differences between the two groups (pMTD and non-pMTD). Further validation of these metrics is needed with voice elicitation tasks that target physiological challenges to the vocal system from baseline vocal acoustic and aerodynamic ouput. Future work should also place greater focus on validating metrics of physiological correlates (eg, neuromuscular processes, laryngeal-respiratory kinematics) across the vocal subsystems over traditional vocal output measures (eg, acoustics, aerodynamics) for patients with pMTD.

LEVEL OF EVIDENCE

II.

Voice Onset Time in Children With and Without Vocal Fold Nodules

PURPOSE

Voice onset time (VOT) of voiceless consonants provides information on the coordination of the vocal and articulatory systems. This study examined whether vocal-articulatory coordination is affected by the presence of vocal fold nodules (VFNs) in children.

METHOD

The voices of children with VFNs (6-12 years) and age- and gender-matched vocally healthy controls were examined. VOT was calculated as the time between the voiceless stop consonant burst and the vocal onset of the vowel. Measures of the average VOT and VOT variability, defined as the coefficient of variation, were calculated. The acoustic measure of dysphonia, cepstral peak prominence (CPP), was also calculated. CPP provides information about the overall periodicity of the signal, with more dysphonic voices having lower CPP values.

RESULTS

There were no significant differences in either average VOT or VOT variability between the VFN and control groups. VOT variability and average VOT were both significantly predicted by the interaction between Group and CPP. There was a significant negative correlation between CPP and VOT variability in the VFN group, but no significant relationship was found in the control group.

CONCLUSIONS

Unlike previous studies with adults, there were no group differences in average VOT or VOT variability in this study. However, children with VFNs who were more dysphonic had increased VOT variability, suggestive of a relationship between dysphonia severity and control of vocal onset during speech production.

Lombard Effect in Individuals With Nonphonotraumatic Vocal Hyperfunction: Impact on Acoustic, Aerodynamic, and Vocal Fold Vibratory Parameters

PURPOSE

This exploratory study aims to investigate variations in voice production in the presence of background noise (Lombard effect) in individuals with nonphonotraumatic vocal hyperfunction (NPVH) and individuals with typical voices using acoustic, aerodynamic, and vocal fold vibratory measures of phonatory function.

METHOD

Nineteen participants with NPVH and 19 participants with typical voices produced simple vocal tasks in three sequential background conditions: baseline (in quiet), Lombard (in noise), and recovery (5 min after removing the noise). The Lombard condition consisted of speech-shaped noise at 80 dB SPL through audiometric headphones. Acoustic measures from a microphone, glottal aerodynamic parameters estimated from the oral airflow measured with a circumferentially vented pneumotachograph mask, and vocal fold vibratory parameters from high-speed videoendoscopy were analyzed.

RESULTS

During the Lombard condition, both groups exhibited a decrease in open quotient and increases in sound pressure level, peak-to-peak glottal airflow, maximum flow declination rate, and subglottal pressure. During the recovery condition, the acoustic and aerodynamic measures of individuals with typical voices returned to those of the baseline condition; however, recovery measures for individuals with NPVH did not return to baseline values.

CONCLUSIONS

As expected, individuals with NPVH and participants with typical voices exhibited a Lombard effect in the presence of elevated background noise levels. During the recovery condition, individuals with NPVH did not return to their baseline state, pointing to a persistence of the Lombard effect after noise removal. This behavior could be related to disruptions in laryngeal motor control and may play a role in the etiology of NPVH.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20415600.

Integrative Review and Framework of Suggested Mechanisms in Primary Muscle Tension Dysphonia

PURPOSE

Despite the high prevalence of primary muscle tension dysphonia (MTD-1), its underlying mechanisms and their interrelationships have yet to be fully identified. The objectives of this integrative review were (a) to describe and classify the suggested underlying mechanisms for MTD-1, (b) to appraise the empirical evidence supporting each of the proposed mechanisms, and (c) to summarize the information in an integrative model.

METHOD

PubMed, Scopus, and CINAHL were searched for all publications pertaining to muscle tension dysphonia. Papers were retained if they included theoretical or empirical data pertaining to underlying mechanisms of MTD-1. A total of 921 papers initially qualified for screening, of which 100 remained for consideration in this review. Underlying mechanisms of MTD-1 were extracted using a consensus approach.

RESULTS

Seven broad categories of putative mechanisms involved in MTD-1 were identified: psychosocial, autonomic, sensorimotor, respiratory, postural, inflammatory, and neuromuscular. These categories were further divided into 19 subcategories detailed in the body of this review article. Based on the reviewed evidence, our proposed integrative model presents MTD-1 as an idiosyncratic motor adaptation to physiological perturbation or perceived threat. Under this model, physiologically or psychologically aversive stimuli can instigate a series of motor adaptations at multiple levels of the nervous system, ultimately disturbing muscle activation patterns and their biomechanical outcomes. Importantly, these adaptations appear to have the potential to become chronic even after threatening stimuli are withdrawn.

CONCLUSIONS

The proposed model highlights the importance of personalized rehabilitation in MTD-1 treatment. Limitations of the literature are discussed to provide guidance for future research aimed at improving our understanding of MTD-1.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.19586065.

Auditory Perception of Roughness and Breathiness by Dysphonic Women

OBJECTIVE

To investigate the auditory perception of roughness and breathiness by dysphonic women.

METHODS

Twenty-two dysphonic native Brazilian Portuguese women participated in this research. All participants underwent audiological evaluation and laryngeal examination to confirm the diagnosis. During the tests, they recorded the sustained vowel /Ɛ/. A speech-language pathologist performed the auditory-perceptual judgment of voice quality for these vocal samples, categorizing the general degree of vocal deviation (mild, moderate, and severe degree) and the predominant type of deviation (roughness or breathiness). Thirty-two (32) stimuli were selected from a voice database, including twenty-four (24) dysphonic voice samples and eight (8) voice samples from vocally healthy women. The authors conducted five perception experiments, being three categorization tasks (normal vs. deviated, breathy vs. nonbreathy, rough vs. nonrough) and two tasks for discriminating the degree of deviation (roughness degree and breathiness degree).

RESULTS

The experiments showed a difference between the answers for presence/absence of deviation, presence/absence of breathiness, and presence/absence of roughness in the stimuli, and a difference in the proportion of similar answers of dysphonic women (P < 0.001) regarding the identification of the deviation. Participants classified a large part of the deviated (57.9%), breathy (63.13%), and rough (65.31%) voices as normal. The degree of vocal deviation (P = 0.008) and the degree of roughness in the stimuli correlated positively with the proportion of similar answers of the participants. As for the discrimination of breathiness degrees, less deviated (normal and mild) voices were less discriminated, and more deviated (moderate and severe) voices were better discriminated. Regarding the discrimination of roughness degrees, only the voices with severe deviations showed good discrimination.

CONCLUSION

Dysphonic women had a high rate of not similar answers in the identification of normal and deviated voices. They identified more than half of the deviated voices as normal. Samples with more severe deviations were proportionally more identified as deviated by the participants. The greater the vocal deviation of the participants' voices, the smallest the number of similar answers. Participants had a high rate of not similar answers in the identification of normal and breathy voices. Dysphonic women show less ability to perceive mildly and moderately breathy voices in the breathy category. Participants had a high rate of similar answers in the identification of normal and rough voices. Dysphonic women show less ability to perceive mildly and moderately breathy voices in the breathy category. Participants show less ability to perceive only mildly roughness voices with similar responses. Dysphonic women could discriminate between voices with adjacent degrees of roughness but had a low percentage of similar answers for discrimination between voices with adjacent degrees of breathiness.

Diseño y validación de una escala vocal multidimensional para la detección del riesgo vocal en docentes

En el colectivo docente es frecuente el mal uso de la voz, para preservar su salud vocal es necesario un diagnóstico precoz. El objetivo del estudio fue diseñar, según criterios de especificidad y sencillez, una escala vocal multidimensional y fiable que contribuya a detectar situaciones de riesgo vocal del docente en el contexto escolar (EVM-D). Participaron 299 docentes, de 18 centros educativos de A Coruña seleccionados aleatoriamente, se dividieron en dos submuestras, una (n =143) para la realización del análisis factorial exploratorio, tanto con Análisis Paralelo como con factorización de ejes principales y rotación oblimin, y otra (n = 156) para el análisis factorial confirmatorio utilizando el método de mínimos cuadrados no ponderados. Una vez analizados los modelos, se optó por uno de tres factores de primer orden (Síntomas vocales, Hábitos de habla y Abusos vocales) y uno de segundo orden (Riesgo vocal). Los índices de bondad de ajuste fueron GFI = ,98, AGFI = ,97, SRMR = ,05; la fiabilidad compuesta (FC) en los tres factores de ,80; ,70 y ,73 y la varianza media extraída (AVE) de ,44; ,43 y ,47 respectivamente; la FC del factor de primer orden fue de ,83 y la AVE ,63. Se obtuvieron valores de corte según el sexo para los percentiles P90, P75 y P60 de riesgo vocal: alto, medio, bajo y muy bajo. La escala EVM-D fiable y consistente podría ser útil para detectar factores etiológicos o síntomas y aplicar la higiene vocal de forma precoz y autónoma por el docente.

The Relationship Between Voice Onset Time and Increase in Vocal Effort and Fundamental Frequency

Purpose Prior work suggests that voice onset time (VOT) may be impacted by laryngeal tension: VOT means decrease when individuals with typical voices increase their fundamental frequency (f o) and VOT variability is increased in individuals with vocal hyperfunction, a voice disorder characterized by increased laryngeal tension. This study further explored the relationship between VOT and laryngeal tension during increased f o, vocal effort, and vocal strain. Method Sixteen typical speakers of American English were instructed to produce VOT utterances under four conditions: baseline, high pitch, effort, and strain. Repeated-measures analysis of variance models were used to analyze the effects of condition on VOT means and standard deviations (SDs); pairwise comparisons were used to determine significant differences between conditions. Results Voicing, condition, and their interaction significantly affected VOT means. Voiceless VOT means significantly decreased for high pitch (p < .001) relative to baseline; however, no changes in voiceless VOT means were found for effort or strain relative to baseline. Although condition had a significant effect on VOT SDs, there were no significant differences between effort, strain, and high pitch conditions relative to baseline. Conclusions Speakers with typical voices likely engage different musculature to increase pitch than to increase vocal effort and strain. The increased VOT variability present with vocal hyperfunction is not seen in individuals with typical voices using increased effort and strain, supporting the assertion that this feature of vocal hyperfunction may be related to disordered vocal motor control rather than resulting from effortful voice production.

An Updated Theoretical Framework for Vocal Hyperfunction

Purpose The purpose of this viewpoint article is to facilitate research on vocal hyperfunction (VH). VH is implicated in the most commonly occurring types of voice disorders, but there remains a pressing need to increase our understanding of the etiological and pathophysiological mechanisms associated with VH to improve the prevention, diagnosis, and treatment of VH-related disorders. Method A comprehensive theoretical framework for VH is proposed based on an integration of prevailing clinical views and research evidence. Results The fundamental structure of the current framework is based on a previous (simplified) version that was published over 30 years ago (Hillman et al., 1989). A central premise of the framework is that there are two primary manifestations of VH-phonotraumatic VH and nonphonotraumatic VH-and that multiple factors contribute and interact in different ways to cause and maintain these two types of VH. Key hypotheses are presented about the way different factors may contribute to phonotraumatic VH and nonphonotraumatic VH and how the associated disorders may respond to treatment. Conclusions This updated and expanded framework is meant to help guide future research, particularly the design of longitudinal studies, which can lead to a refinement in knowledge about the etiology and pathophysiology of VH-related disorders. Such new knowledge should lead to further refinements in the framework and serve as a basis for improving the prevention and evidence-based clinical management of VH.