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.

The Relationship Between Pitch Discrimination and Acoustic Voice Measures in a Cohort of Female Speakers

BACKGROUND

Evidence across a range of musically trained, hearing disordered and voice disordered populations present conflicting results regarding the relationship between pitch discrimination (PD) and voice quality. PD characteristics of female speakers with and without a musical training background and no self-reported voice disorder, and the relationship between PD and voice quality in this particular population, have not been investigated.

AIMS

To evaluate PD characteristics in a cohort of female participants without a self-reported voice disorder and the relationship between PD and acoustic voice measures.

METHOD

One hundred fourteen female participants were studied, all of whom self-reported as being non-voice disordered. All completed the Newcastle Assessment of Pitch Discrimination which involved a two-tone PD task. Their voices were recorded producing standardized vocal tasks. Voice samples were acoustically analyzed for frequency-domain measures (fundamental frequency and its standard deviation, and harmonics-to-noise ratio) and spectral-domain measures (cepstral peak prominence and the Cepstral/Spectral Index of Dysphonia). Data were analyzed for the whole cohort and for musical and non-musical training backgrounds.

RESULTS

In the whole cohort, there were no significant correlations between PD and acoustic voice measures. PD accuracy in musically trained speakers was better than in non-trained speakers and correlated with fundamental frequency standard deviation in prolonged vowel tasks. Vocalists demonstrated superior PD accuracy and fundamental frequency standard deviation in prolonged vowels compared to instrumentalists but did not show significant correlations between PD and acoustic measures. The Newcastle Assessment of Pitch Discrimination was a reliable tool, showing moderate-good prediction value in differentiating musical background.

CONCLUSIONS

There was little evidence of a relationship between PD and acoustic measures of voice quality, regardless of musical training background and superior PD accuracy among the musically trained. These data do not support ideas concerning the co-development of perception and action among individuals identified as having voice quality measures within normal ranges. Numerous measures of voice quality, including measures sensitive to pitch, did not distinguish across musically and non-musically trained individuals, despite individual differences in pitch discrimination.

"Lombard Effect" and Voice Changes in Adductor Laryngeal Dystonia: A Pilot Study

OBJECTIVES

The aim was to describe the acoustic, auditory-perceptive, and subjective voice changes under the Lombard effect (LE) in adductor laryngeal dystonia (AdLD) patients.

METHODS

Subjective perception of vocal effort (OMNI Vocal Effort Scale OMNI-VES), Maximum Phonation Time (MPT), and the perceptual severity of dysphonia (GRBAS scale) were assessed in condition of stillness and under LE in 10 AdLD patients and in 10 patients with typical voice. Speakers were asked to produce the sustained vowel /a/ and to read a phonetically balanced text aloud. Using the PRAAT software, the following acoustic parameters were analyzed: Mean Pitch (Hz), Minimum and Maximum Intensity (dB), the Fraction of Locally Unvoiced Frames, the Number of Voice Breaks, the Degree of Voice Breaks (%), the Cepstral Peak Prominence-Smoothed (CPPS) (dB).

RESULTS

Under LE, the AdLD group showed a decrease of both G and S parameters of GRBAS and subjective effort, mean MPT increased significantly; in the controls there were no significant changes. In both groups under LE, pitch and intensity of the sustained vowel /a/ significantly increased consistently with LE. In the AdLD group the mean gain of OMNI-VES score and the mean gain of each parameter of the speech analysis were significantly greater than the controls' ones.

CONCLUSION

Auditory feedback deprivation obtained under LE improves subjective, perceptual-auditory, and acoustics parameters of AdLD patients. These findings encourage further research to provide new knowledge into the role of the auditory system in the pathogenesis of AdLD and to develop new therapeutic strategies.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:3754-3760, 2024.

Reducing Vocal Fatigue With Bone Conduction Devices: Comparing Forbrain and Sidetone Amplification

PURPOSE

Altered auditory feedback research aims to identify methods to strengthen speakers' awareness of their own voicing behaviors, diminish their perception of vocal fatigue, and improve their voice production. This study aims to compare the effects of two bone conduction devices that provide altered auditory feedback.

METHOD

Twenty participants (19-33 years old, age: M [SD] = 25.5 [3.85] years) participated in a vocal loading task using a standard Forbrain device that provides filtered auditory feedback via bone conduction and a modified Forbrain device that provides only sidetone amplification, and a control condition with no device was also included. They rated their vocal fatigue on a visual analog scale every 2 min during the vocal loading task. Additionally, pre- and postloading voice samples were analyzed for acoustic voice parameters.

RESULTS

Across all participants, the use of bone conduction-altered auditory feedback devices resulted in a lower vocal fatigue when compared to the condition with no feedback. During the pre- and postvoice samples, the sound pressure level decreased significantly during feedback conditions. During feedback conditions, spectral mean and standard deviation significantly decreased, and spectral skew significantly increased.

CONCLUSION

The results promote bone conduction as a possible preventative tool that may reduce self-reported vocal fatigue and compensatory voice production for healthy individuals without voice disorders.

Effects of Cortical Stimulation on Feedback-Dependent Vocal Control in Non-Human Primates

OBJECTIVES

Hearing plays an important role in our ability to control voice, and perturbations in auditory feedback result in compensatory changes in vocal production. The auditory cortex (AC) has been proposed as an important mediator of this behavior, but causal evidence is lacking. We tested this in an animal model, hypothesizing that AC is necessary for vocal self-monitoring and feedback-dependent control, and that altering activity in AC during vocalization will interfere with vocal control.

METHODS

We implanted two marmoset monkeys (Callithrix jacchus) with bilateral AC electrode arrays. Acoustic signals were recorded from vocalizing marmosets while altering vocal feedback or electrically stimulating AC during random subsets of vocalizations. Feedback was altered by real-time frequency shifts and presented through headphones and electrical stimulation delivered to individual electrodes. We analyzed recordings to measure changes in vocal acoustics during shifted feedback and stimulation, and to determine their interaction. Results were correlated with the location and frequency tuning of stimulation sites.

RESULTS

Consistent with previous results, we found electrical stimulation alone evoked changes in vocal production. Results were stronger in the right hemisphere, but decreased with lower currents or repeated stimulation. Simultaneous stimulation and shifted feedback significantly altered vocal control for a subset of sites, decreasing feedback compensation at some and increasing it at others. Inhibited compensation was more likely at sites closer to vocal frequencies.

CONCLUSIONS

Results provide causal evidence that the AC is involved in feedback-dependent vocal control, and that it is sufficient and may also be necessary to drive changes in vocal production.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:1-10, 2023.

Voice Biofeedback via Bone Conduction Headphones: Effects on Acoustic Voice Parameters and Self-Reported Vocal Effort in Individuals With Voice Disorders

PURPOSE

This study explores sidetone amplification (amplified playback of one's own voice) provided via bone conduction in participants with voice disorders. The effects of bone conduction feedback on acoustic voice parameters and vocal effort ratings are examined.

METHODS

Speech samples of 47 participants with voice disorders were recorded in three auditory feedback conditions: two with sidetone amplification delivered via bone conduction and one condition with no alteration of the feedback. After each task, the participants rated their vocal effort on a visual analog scale. The voice recordings were evaluated by a speech-language pathologist through the GRBAS scale and processed to calculate the within-participant centered sound pressure level (SPL) values, the mean pitch strength (PS), the time dose (Dt%), and cepstral peak prominence smoothed (CPPS). The effects of the feedback conditions on these acoustic parameters and vocal effort ratings were analyzed.

RESULTS

The high sidetone amplification condition resulted in a statistically significant decrease in the within-participant centered SPL values and mean pitch strength across all participants. The feedback conditions had no statistically significant effects on the vocal effort ratings, time dose (Dt%), or CPPS.

CONCLUSIONS

This study provides an evidence that bone conduction sidetone amplification contributes to a consistent adaptation in the within-participant centered SPL values (ΔSPL) in patients with vocal hyperfunction, glottal insufficiency, and organic/neurological laryngeal pathologies compared to conditions with no feedback.

LaDIVA: A neurocomputational model providing laryngeal motor control for speech acquisition and production

Many voice disorders are the result of intricate neural and/or biomechanical impairments that are poorly understood. The limited knowledge of their etiological and pathophysiological mechanisms hampers effective clinical management. Behavioral studies have been used concurrently with computational models to better understand typical and pathological laryngeal motor control. Thus far, however, a unified computational framework that quantitatively integrates physiologically relevant models of phonation with the neural control of speech has not been developed. Here, we introduce LaDIVA, a novel neurocomputational model with physiologically based laryngeal motor control. We combined the DIVA model (an established neural network model of speech motor control) with the extended body-cover model (a physics-based vocal fold model). The resulting integrated model, LaDIVA, was validated by comparing its model simulations with behavioral responses to perturbations of auditory vocal fundamental frequency (fo) feedback in adults with typical speech. LaDIVA demonstrated capability to simulate different modes of laryngeal motor control, ranging from short-term (i.e., reflexive) and long-term (i.e., adaptive) auditory feedback paradigms, to generating prosodic contours in speech. Simulations showed that LaDIVA's laryngeal motor control displays properties of motor equivalence, i.e., LaDIVA could robustly generate compensatory responses to reflexive vocal fo perturbations with varying initial laryngeal muscle activation levels leading to the same output. The model can also generate prosodic contours for studying laryngeal motor control in running speech. LaDIVA can expand the understanding of the physiology of human phonation to enable, for the first time, the investigation of causal effects of neural motor control in the fine structure of the vocal signal.

What Can Altered Auditory Feedback Paradigms Tell Us About Vocal Motor Control in Individuals With Voice Disorders?

Purpose

The goal of this review article is to provide a summary of the progression of altered auditory feedback (AAF) as a method to understand the pathophysiology of voice disorders. This review article focuses on populations with voice disorders that have thus far been studied using AAF, including individuals with Parkinson's disease, cerebellar degeneration, hyperfunctional voice disorders, vocal fold paralysis, and laryngeal dystonia. Studies using AAF have found that individuals with Parkinson's disease, cerebellar degeneration, and laryngeal dystonia have hyperactive auditory feedback responses due to differing underlying causes. In persons with PD, the hyperactivity may be a compensatory mechanism for atypically weak feedforward motor control. In individuals with cerebellar degeneration and laryngeal dystonia, the reasons for hyperactivity remain unknown. Individuals with hyperfunctional voice disorders may have auditory-motor integration deficits, suggesting atypical updating of feedforward motor control.

Conclusions

These findings have the potential to provide critical insights to clinicians in selecting the most effective therapy techniques for individuals with voice disorders. Future collaboration between clinicians and researchers with the shared objective of improving AAF as an ecologically feasible and valid tool for clinical assessment may provide more personalized therapy targets for individuals with voice disorders.

Pitch Discrimination Testing in Patients with a Voice Disorder

Auditory perception plays an important role in voice control. Pitch discrimination (PD) is a key index of auditory perception and is influenced by a variety of factors. Little is known about the potential effects of voice disorders on PD and whether PD testing can differentiate people with and without a voice disorder. We thus evaluated PD in a voice-disordered group (n = 71) and a non-voice-disordered control group (n = 80). The voice disorders included muscle tension dysphonia and neurological voice disorders and all participants underwent PD testing as part of a comprehensive voice assessment. Percentage of accurate responses and PD threshold were compared across groups. The PD percentage accuracy was significantly lower in the voice-disordered group than the control group, irrespective of musical background. Participants with voice disorders also required a larger PD threshold to correctly discriminate pitch differences. The mean PD threshold significantly discriminated the voice-disordered groups from the control group. These results have implications for the voice control and pathogenesis of voice disorders. They support the inclusion of PD testing during comprehensive voice assessment and throughout the treatment process for patients with voice disorders.

Real-time feedback control of voice in cochlear implant recipients

OBJECTIVES

To evaluate feedback-dependent vocal control in cochlear implant patients using pitch-shifted auditory feedback.

METHODS

Twenty-three CI recipients with at least 6 months of implant experience were enrolled. Vocal recordings were performed while subjects repeated the vowel /e/ and vocal signals were altered in real-time using a digital effects processor to introduce a pitch-shift, presented back to subjects using headphones. Recordings were analyzed to determine pitch changes following the pitch-shifted feedback, and results compared to the magnitude of the shift as well as patient demographics.

RESULTS

Consistent with previous results, CI patients' voices had higher pitches with their implant turned off, a change explainable by increases in vocal loudness without the CI. CI patients rapidly compensated for pitch-shifted feedback by changing their vocal pitch, but only for larger shifts. Considerable inter-subject variability was present, and weakly correlated with the duration of implant experience and implant sound thresholds.

CONCLUSIONS

CI patients, like normal hearing individuals, are capable of real-time feedback-dependent control of their vocal pitch. However, CI patients are less sensitive to small feedback changes, possibly a result of courser CI frequency precision, and may explain poorer than normal vocal control in these patients.

LEVEL OF EVIDENCE

Level 3b.

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.

Auditory Feedback Control of Vocal Pitch in Spasmodic Dysphonia

OBJECTIVES/HYPOTHESIS

Hearing plays an important role in the maintenance of vocal control in normal individuals. In patients with spasmodic dysphonia (SD), however, the ability to maintain sustained control of phonation is impaired. The origins of SD are unknown, and it is unclear whether auditory feedback-dependent vocal control is compromised in these patients.

STUDY DESIGN

Prospective case-control study.

METHODS

We tested 15 SD patients and 11 age-matched controls. Voice recordings were performed while subjects repeated the vowel /e/ and auditory feedback of their vocal sounds was altered in real-time to introduce a pitch-shift (±2 semitones), presented back to subjects using headphones. Recordings were analyzed to determine voice changes following the pitch-shifted feedback. Results were further compared with patient demographics and subjective measures of dysphonia, including the Voice Handicap Index (VHI).

RESULTS

Despite considerable pitch variability and vocal breaks, SD patients exhibited significantly higher average vocal pitch compensation than control subjects. SD patients also exhibited greater variability than controls. However, there were no significant correlations between vocal compensation and patient demographics, although there was a significant inverse correlation with VHI.

CONCLUSIONS

In this pilot study, patients with SD exhibited increased sensitivity to altered auditory feedback during sustained phonation. These results are consistent with recent theories of SD as a disorder of sensory-motor feedback processing, and suggest possible avenues for future investigation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:2070-2075, 2021.

Brain Activity in Patients With Unilateral Vocal Fold Paralysis Detected by Functional Magnetic Resonance Imaging

OBJECTIVES

Understanding brain activity in response to unilateral vocal fold paralysis is essential to determine the neural compensatory mechanism underlying adaptation to voice disorders and to develop novel and improved rehabilitation programs for these disorders. We aimed to clarify brain activity during phonation (prolonged vowel, |i:|) in patients with chronic left vocal fold paralysis (LVFP) and compare with that in normal controls.

STUDY DESIGN

Case-control study.

METHODS

This functional magnetic resonance imaging (fMRI) study of an event-related task comprised 12 individuals with LVFP of more than 6 months duration and 12 healthy controls. The experimental task alternated phonation (prolonged vowel, |i:|) and no phonation (rest) conditions. The functional images obtained were single-shot gradient-echo echo-planar imaging. The volumes were acquired parallel to the anterior-posterior commissure plane and were sensitive to BOLD contrast. Data sets were processed and statistically analyzed using Statistical Parametric Mapping 8 software. Within-group analyses were conducted by applying the one-sample t test (P < 0.001, uncorrected). A random-effects analysis was used for group comparison.

RESULTS

The LVFP group showed significantly higher brain activity in the right premotor areas, left parietal lobule, right primary somatosensory areas, and bilateral supplementary motor area and lower brain activity in the auditory-related areas of the superior temporal gyrus. There were no significant correlations of the percent signal change on fMRI with disease duration, maximum phonation time, or age.

CONCLUSION

Patients with chronic unilateral vocal fold paralysis have stronger activity during voluntary phonation in various central networks. More detailed information on the central nervous system regions related to voluntary phonation from early to chronic phase is needed to understand the compensatory mechanisms in vocal fold paralysis and to establish an effective rehabilitation program. This is the first report to investigate brain activity in chronic unilateral vocal fold paralysis.

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.

Abnormally increased vocal responses to pitch feedback perturbations in patients with cerebellar degeneration

Cerebellar degeneration (CD) has deleterious effects on speech motor behavior. Recently, a dissociation between feedback and feedforward control of speaking was observed in CD: Whereas CD patients exhibited reduced adaptation across trials to consistent formant feedback alterations, they showed enhanced within-trial compensation for unpredictable formant feedback perturbations. In this study, it was found that CD patients exhibit abnormally increased within-trial vocal compensation responses to unpredictable pitch feedback perturbations. Taken together with recent findings, the results indicate that CD is associated with a general hypersensitivity to auditory feedback during speaking.