Acoustic analysis of the tremulous voice: assessing the utility of the correlation dimension and perturbation parameters

A Cross-sectional Study of Perceptual and Acoustic Voice Characteristics in Healthy Aging

PURPOSE

The human voice qualitatively changes across the lifespan. Although some of these vocal changes may be pathologic, other changes likely reflect natural physiological aging. Normative data for voice characteristics in healthy aging is limited and disparate studies have used a range of different acoustic features, some of which are implicated in pathologic voice changes. We examined the perceptual and acoustic features that predict healthy aging.

METHOD

Participants (N = 150) aged between 50 and 92 years performed a sustained vowel task. Acoustic features were measured using the Multi-Dimensional Voice Program and the Analysis of Dysphonia in Speech and Voice. We used forward and backward variable elimination techniques based on the Bayesian information criterion and linear regression to assess which of these acoustic features predict age and perceptual features. Hearing thresholds were determined using pure-tone audiometry tests at frequencies 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. We further explored potential relationships between these acoustic features and clinical assessments of voice quality using the Consensus Auditory-Perceptual Evaluation of Voice.

RESULTS

Chronological age was significantly predicted by greater voice turbulence, variability of cepstral fundamental frequency, low relative to high spectral energy, and cepstral intensity. When controlling for hearing loss, age was significantly predicted by amplitude perturbations and cepstral intensity. Clinical assessments of voice indicated perceptual characteristics of speech were predicted by different acoustic features. For example, breathiness was predicted by the soft phonation index, mean cepstral peak prominence, mean low-high spectral ratio, and mean cepstral intensity.

CONCLUSIONS

Findings suggest that acoustic features that predict healthy aging are different than those previously reported for the pathologic voice. We propose a model of healthy and pathologic voice development in which voice characteristics are mediated by the inability to monitor vocal productions associated with age-related hearing loss. This normative data of healthy vocal aging may assist in separating voice pathologies from healthy aging.

Biomechanical Parameters of Voice in Parkinson's Disease Patients

INTRODUCTION

Previous research on voice in Parkinson's disease (PD) has consistently demonstrated alterations in acoustic parameters, including fundamental frequency (F0), maximum phonation time, Shimmer, and Jitter. However, investigations into acoustic parameter alterations in individuals with PD are limited.

METHODS

We conducted an experimental study involving 20 PD patients (six women and fourteen men). Subjective measures of voice (VHI-30 scale and GRBAS) and objective measures using the OnlineLAB App tool for analyzing biomechanical correlates of voice were recorded. The app analyzed a total of 22 biomechanical parameters of voice.

RESULTS

The results of subjective measures were consistent with findings from previous studies. However, the results of objective measures did not align with studies that employed acoustic measures.

CONCLUSIONS

The biomechanical analysis revealed alterations in various parameters according to gender. These findings open up a new avenue of research in voice analysis for patients with PD, whether through acoustic or biomechanical analysis, aiming to determine whether the observed changes in these patients' voices are attributable to age or disease progression. This line of investigation will help elucidate the relative contribution of these factors to vocal alterations in PD patients and provide a more comprehensive understanding of the underlying mechanisms.

Voice Analysis in Patients with Essential Tremor

OBJECTIVE

The objective of this study was to reveal the phonetic characteristics of patients with or without voice tremor in patients with essential tremor (ET), determine whether these phonetic features are ET specific, and test the influence of ET on vocal tremor.

METHODS

The study included a total of 30 patients with ET and 29 healthy volunteers. The severity of ET was evaluated using the Washington Heights Inwood Genetic Study of Essential Tremor (WHIGET) tremor rating scale. Patients with major tremor complaints for at least 3years, WHIGET scoring scores below 15, and patients newly diagnosed in our clinic and for whom drug therapy has not yet been started were selected.

RESULTS

A total of 59 participants (n = 34 with ET and n = 25 as control) were included in the study. The ages of the participants ranged from 20 to 82years, with a mean age of 54.50 ± 15.04years. The gender distribution was 57.6% male and 42.4% female, and there was no statistically significant difference between the two groups in terms of age and gender. The study found that individuals with ET had significantly higher jitter, shimmer, S/Z, Pataka, frequency tremor intensity index, amplitude tremor intensity index, and frequency tremor power index values than the control group. However, there was no statistically significant difference between the two groups in terms of MPT, frequency tremor cyclicality, amplitude tremor cyclicality, frequency tremor frequency, and amplitude tremor frequency values.

CONCLUSION

Our study shows that, even in the absence of essential voice tremor, there is an effect of ET on voice quality. These findings contribute to the understanding of the nonmotor symptoms of ET and may aid in the diagnosis and management of this condition. Further research is needed to explore the potential use of acoustic analysis parameters in the diagnosis and monitoring of ET.

Acoustical and Perceptual Analysis of Voice in Individuals with Parkinson's Disease

Parkinson's disease is a neurodegenerative disorder that affects motor efficiency which is also required for voice production. Voice is part of the identity of a person, any abnormality in voice quality hampers the quality of communication, and quality of life. This study aimed to analyse the voice of individuals with Parkinson's disease objectively through acoustic analysis, and subjectively through perceptual analysis. Quasi-experimental study conducted in a tertiary health care centre. The study comprised two groups: 12 individuals with Parkinson's disease (11 males and 1 female, mean age: 72.41 years), and 12 healthy controls (10 males and 2 females, mean age: 53.83 years). The voice samples of all the participants were recorded and analyzed using the MDVP software of CSL 4500. The voice samples were analyzed for eleven acoustical parameters, and the perceptual analysis was carried out using the GRBAS scale by two experienced Speech Language Pathologists. Mann-Whitney U test was performed to compare the two groups of participants, and Cronbach's alpha test was performed to find the inter-judge reliability between the perceptual ratings of two listeners. Acoustical comparison showed significant variations in seven parameters (jitter, shimmer, PPQ, APQ, Fatr Hz, Fftr, ATRI), and the perceptual analysis between two listeners showed a fair amount of reliability.

[Current methods of acoustic analysis of voice: a review]

Acoustic analysis of the voice, as an objective, quantitative, non-invasive and reproducible method for the evaluation of voice quality, can be used to detect and analyze the acoustic characteristics of normal, artistic or pathological voice. With the development of medicine, physics, statistics, and artificial intelligence technology, there are new advances in the study of voice acoustic analysis, especially in terms of acoustic parameters. In addition, artificial neural networks can be used to perform complex multi-parameter analysis, which greatly improves the efficiency of acoustic analysis. This paper provides an overview of the methods of acoustic analysis and its latest development.

Acoustic Voice Analysis of Normal and Pathological Voices in Indian Population Using Praat Software

Acoustic voice analysis is still a valuable technique which enables voice clinicians to compare voices to differentiate them into normal and abnormal. The present study was undertaken to standardize acoustic voice parameters in normal healthy adult individuals and gender comparison among them and also acoustic voice analysis of pathological voices and it's comparison with normal healthy voices. Voice samples of vowels /a/, /i/ and /u/ of 80 normal healthy adults (males = 40, females = 40) of control group and 40 patients with dysphonic voice of case group collected and acoustic voice parameters were extracted by using Praat software. There were statistically significant higher values of fundamental frequency (F0) in females, while jitter local (%), shimmer local (%) and harmonic to noise ratio (HNR) had no gender differences in normal healthy voices. Pathological voices of case group subjects with laryngeal pathologies had statistically significant higher values of jitter local (%), shimmer local (%) and lower values of HNR as compare to normal healthy voices of control group. Objective voice analysis by using Praat software is convenient, reliable and cost effective method. This study establishes normative acoustic voice parameters in normal healthy adults. There are no gender differences in adult healthy voices except fundamental frequency (F0), which is higher in females. Patients who are with dysphonic voices due to laryngeal pathologies had altered values of acoustic parameters compared to normophonic adults and clinicians can precisely differentiate pathological voices from normophonics.

A Tutorial Review on Clinical Acoustic Markers in Speech Science

PURPOSE

The human voice changes with the progression of neurological disease and the onset of diseases that affect articulators, often decreasing the effectiveness of communication. These changes can be objectively measured using signal processing techniques that extract acoustic features. When measuring acoustic features, there are often several steps and assumptions that might be known to experts in acoustics and phonetics, but are less transparent for other disciplines (e.g., clinical medicine, speech pathology, engineering, and data science). This tutorial describes these signal processing techniques, explicitly outlines the underlying steps for accurate measurement, and discusses the implications of clinical acoustic markers.

CONCLUSIONS

We establish a vocabulary using straightforward terms, provide visualizations to achieve common ground, and guide understanding for those outside the domains of acoustics and auditory signal processing. Where possible, we highlight the best practices for measuring clinical acoustic markers and suggest resources for obtaining and further understanding these measures.

[Diagnostic Value of Speech Acoustic Analysis in Parkinson's Disease]

Screening for and identifying patients with Parkinson's disease (PD) at an early stage and forming accurate diagnosis of PD during the course of the progression of the disease are of essential importance but still remain challenging for the clinical diagnosis and treatment of PD. One of the common clinical manifestations of PD is speech impairment, or voice impairment. Thanks to the recent advances in the field of acoustic analysis, a large number of acoustic parameters have been proposed for evaluating speech impairment quantitatively. Early identification and accurate diagnosis of PD was henceforth made possible through the application of speech acoustic analysis. Herein, we summarized the latest research findings on the application of acoustic analysis in PD diagnosis. We reported some acoustic parameters commonly used in the evaluation of voice impairment in PD patients. Then, we presented the diagnostic value of acoustic analysis in developing accurate diagnosis, early screening and differential diagnosis. Furthermore, we discussed the drawbacks and prospects of current studies, intending to enhance understanding of acoustic analysis of PD patients and its potential diagnostic values.

A Preliminary Study on the Effect of Bhramari Pranayama on Voice of Prospective Singers

INTRODUCTION

Bhramari Pranayama (BP) is a yogic breathing technique that involves producing a vibrating constant pitch sound emulating the buzzing of bumblebee. Since BP deals with breathing and humming in the sustained pitch, it is hypothesized that it can have implications for improving voice quality in individuals. However, there is a dearth of research available to support this assumption. Further, there are no published reports on the effect of BP on voice quality in prospective singers group.

AIM

Current study was taken up to explore the effect induced by BP in the voice characteristics/quality of prospective singers.

METHOD

The participants included 30 healthy prospective singers in the age range of 18-35 years who were attending music schools within the state of Karnataka, India. BP regimen was demonstrated to all individuals. The voice recordings of the participants were obtained on day 0 and day 30 of BP practice. Acoustic analysis was performed to obtain AVQI and its constituent parameters and voice parameters from the MDVP program.

RESULT

Among the AVQI and its constituent parameters, Cepstral peak prominence-smoothed, Slope LTAS, and Tilt LTAS showed significant differences before and after BP. MDVP showed a significant difference in tremor measures before and after the practice of BP.

DISCUSSION

Results of the present study indicated positive effects of BP on the voice characteristics of the prospective singers and it is reflected in objective acoustic outcome parameters of AVQI and MDVP. This supports the assumption that BP which involves yogic breathing will have beneficial effects on vocal physiology in turn leading to improved voice quality in these individuals. However, it is of future interest to validate these findings on larger samples and populations with different outcome measures. Also, future studies are warranted to verify the efficacy of BP in improving vocal quality and vocal efficiency of individuals with dysphonia.

Cognitive Determinants of Dysarthria in Parkinson's Disease: An Automated Machine Learning Approach

BACKGROUND

Dysarthric symptoms in Parkinson's disease (PD) vary greatly across cohorts. Abundant research suggests that such heterogeneity could reflect subject-level and task-related cognitive factors. However, the interplay of these variables during motor speech remains underexplored, let alone by administering validated materials to carefully matched samples with varying cognitive profiles and combining automated tools with machine learning methods.

OBJECTIVE

We aimed to identify which speech dimensions best identify patients with PD in cognitively heterogeneous, cognitively preserved, and cognitively impaired groups through tasks with low (reading) and high (retelling) processing demands.

METHODS

We used support vector machines to analyze prosodic, articulatory, and phonemic identifiability features. Patient groups were compared with healthy control subjects and against each other in both tasks, using each measure separately and in combination.

RESULTS

Relative to control subjects, patients in cognitively heterogeneous and cognitively preserved groups were best discriminated by combined dysarthric signs during reading (accuracy = 84% and 80.2%). Conversely, patients with cognitive impairment were maximally discriminated from control subjects when considering phonemic identifiability during retelling (accuracy = 86.9%). This same pattern maximally distinguished between cognitively spared and impaired patients (accuracy = 72.1%). Also, cognitive (executive) symptom severity was predicted by prosody in cognitively preserved patients and by phonemic identifiability in cognitively heterogeneous and impaired groups. No measure predicted overall motor dysfunction in any group.

CONCLUSIONS

Predominant dysarthric symptoms appear to be best captured through undemanding tasks in cognitively heterogeneous and preserved cohorts and through cognitively loaded tasks in patients with cognitive impairment. Further applications of this framework could enhance dysarthria assessments in PD. © 2021 International Parkinson and Movement Disorder Society.

Automatic Classification of Healthy Subjects and Patients With Essential Vocal Tremor Using Probabilistic Source-Filter Model Based Noise Robust Pitch Estimation

Essential voice tremor (EVT) is a voice disorder resulting from dyscoordination within the laryngeal musculature. A low-frequency fluctuations of fundamental voice frequency or the strength of excitation amplitude is the main consequence of the disorder. The automatic classification of healthy control and EVT is useful tool for the clinicians. A typical automatic EVT classification involves three steps. The first step is to compute the pitch contour from the speech. The second step is to compute the features from the pitch contour, and the final step is to use a classifier to classify the features into healthy or EVT. It is shown that a high-resolution pitch contour estimated from the glottal closure instants (GCIs) is useful for EVT classification. The HPRC estimation can be very poor in the presence of noise. Hence, a probabilistic source filter model based noise robust GCI detection is used for HPRC estimation. The Empirical mode decomposition based feature extraction is used followed by a support vector machine classifier. The EVT classification performance is evaluated using recordings from 45 subjects. The proposed method is found to perform better than the baseline techniques in eight different additive noise conditions with six SNR levels.

Intraoperative Evaluation of Essential Vocal Tremor in Deep Brain Stimulation Surgery

Purpose Essential vocal tremor (EVT) is a prevalent and difficult-to-manage voice disorder. There is evidence that deep brain stimulation (DBS) of the ventral intermediate nucleus (Vim) of the thalamus may be beneficial for treating EVT. The objective of this preliminary investigation was to conduct intraoperative voice assessments during Vim-DBS implantation in order to evaluate immediate voice outcomes in medication-refractory essential tremor patients with co-occurring EVT. Method Seven adult subjects diagnosed with EVT undergoing Vim-DBS surgery participated in this investigation. Voice samples of sustained vowels were collected by a speech-language pathologist preoperatively and intraoperatively, immediately following Vim-DBS electrode placement. Voice evaluation included objective acoustic assessment of the rate and extent of EVT fundamental frequency and intensity modulation and subjective perceptual ratings of EVT severity. Results The rate of intensity modulation, extent of fundamental frequency modulation, and perceptual rating of EVT severity were significantly reduced intraoperatively as compared to preoperatively. Moderate, positive correlations were appreciated between a subset of acoustic measures and perceptual severity ratings. Conclusions The results of this study demonstrate a speech-language pathologist can conduct intra-operative evaluation of EVT during DBS surgery. Using a noninvasive, simple acoustic recording method, we were able to supplement perceptual subjective observation with objective assessment and demonstrate immediate, intraoperative improvements in EVT. The findings of this analysis inform the added value of intraoperative voice evaluation in Vim-DBS patients and contribute to the growing body of literature seeking to evaluate the efficacy of DBS as a treatment for EVT.

The Sound of Inattention: Predicting Mind Wandering with Automatically Derived Features of Instructor Speech

Lecturing in a classroom environment is challenging - instructors are tasked with maintaining students’ attention for extended periods of time while they are speaking. Previous work investigating the influence of speech on attention, however, has not yet been extended to instructor speech in live classroom lectures. In the current study, we automatically extracted acoustic features from live lectures to determine their association with rates of classroom mind-wandering (i.e., lack of student attention). Results indicated that five speech features reliably predicted classroom mind-wandering rates (Harmonics-to-Noise Ratio, Formant 1 Mean, Formant 2 Mean, Formant 3 Mean, and Jitter Standard Deviation). These speaker correlates of mind-wandering may be a foundation for developing a system to provide feedback in real-time for lecturers online and in the classroom. Such a system may prove to be highly beneficial in developing real-time tools to retain student attention, as well as informing other applications outside of the classroom.

Cross-cultural Adaptation and Validation of the Greek Voice Handicap Index-10 (GVHI-10) With Additional Receiver Operating Characteristic Analysis

OBJECTIVE(S)

The use of subjective evaluation tools are proven useful and of high clinical value in the case of voice disordered population. For that type of evaluation, self-assessment questionnaires about the severity of the voice like Voice Handicap Index-30 (VHI-30) have been developed. The VHI-30 is the most studied tool which includes psychometrically robustness while guiding physician's therapeutic decision making. Additionally, a valid abbreviated version of VHI-30 was developed for the first time in the Greek Language which is named as Greek Voice Handicap Index-10 (GVHI-10). Consequently, the aim of our study was to validate the proposed version of the VHI-10.

METHODS

Ninety nondysphonic individuals and 90 dysphonic patients were classified by Otolaryngologists and Speech Language Pathologists. The study's subjects were evaluated with endoscopy and stroboscopy. Also, they were administrated the GVHI-30 and the translated version of the Voice Evaluation Template (VEF). The GVHI-10 was extracted by the Greek version of VHI-30.

RESULTS

The group with voice disorders exhibited higher statistical significance in all GVHI-10 scores compared to those of the control group. The GVHI-10 showed a high internal consistency (Cronbach's a = 0.915 and split-half reliability coefficient equal to 0.86), good sensitivity compared to Greek VHI-30 (r = 0.764, P = 0.000) and intraclass correlation. A total cut-off point equal to 6.50 (AUC: 0.964; P < 0.001) was also calculated.

CONCLUSIONS

The proposed version of GVHI-10 distinguished the perceived levels of voice between dysphonic and nondysphonic groups and between different voice disordered populations. The GVHI-10 is shown to be clinically valid and sensitive exhibiting high reliability.

Comparing the Nonlinear Dynamic Acoustic Parameters of Healthy Adult and Pediatric Voices

Objectives:

The aims of this study were to compare nondysphonic adult and pediatric voices using linear and nonlinear acoustic parameters and to evaluate the ability of adult spectrum convergence ratio (SCR) and rate of divergence (ROD) reference values to correctly identify a pediatric voice type as periodic or aperiodic.

Methods:

Twenty adult and 36 pediatric nondysphonic voice samples were collected and analyzed using linear and nonlinear acoustic parameters. Absence of voice disorder was confirmed using perceptual acoustic and spectral analysis. Mean values for jitter, shimmer, SCR, and ROD were compared between adults and children, across specific age groups, and within genders. Using adult reference values for SCR and ROD, samples were classified as primarily periodic or aperiodic and typed using spectral analysis. Rates of accurate typing were also compared between subject groups.

Results:

Overall, jitter and shimmer were similar among the adult and pediatric age groups. ROD was significantly different among the 3 pediatric and 1 adult group; the pediatric age groups were similar to one another. Adult SCR was also significantly different from all of the pediatric age groups. In adult men, ROD and SCR were significantly different from all of the pediatric age groups; the pediatric age groups were similar to one another. In female subjects, ROD was significantly different among all age groups. The ROD and SCR reference values were significantly better at categorizing adult voice types compared with pediatric voice types.

Conclusions:

In healthy subjects, SCR and ROD have discriminatory power for identifying adult versus pediatric voices, while jitter and shimmer cannot differentiate between the 2 groups. However, age- and gender-specific pediatric reference values must be determined to accurately classify voice types using SCR and ROD.

Influence of sampling rate on voice analysis for assessment of Parkinson's disease

Parkinson's diagnosis through voice analysis (PDVA) has been attracting increasing attention. In this paper, the influence of sampling rate on PDVA is studied. By analyzing the main difficulties that hamper the development of PDVA, the significance of seeking guidelines on sampling rate is discussed. Then voices from both healthy controls and patients with Parkinson's disease are recorded, for which the sampling rate used is given special consideration. Recordings of other sampling rates are generated via down sampling the recorded voices. Then it is proposed to adopt six metrics from four levels to assess the impacts of sampling rate, which are information entropy, reconstruction error, feature correlation, classification accuracy, computational cost, and the storage cost. Through extensive experiments, basic guideline to seek an appropriate sampling rate is provided. It is concluded that a sampling rate of 96 kHz is preferred when no limits of storage and computational costs are imposed. However, a lower sampling rate may be needed if the storage size and computational complexity are the main concerns.

Quantitative Analysis of Relationship Between Hypokinetic Dysarthria and the Freezing of Gait in Parkinson's Disease

Hypokinetic dysarthria (HD) and freezing of gait (FOG) are both axial symptoms that occur in patients with Parkinson's disease (PD). It is assumed they have some common pathophysiological mechanisms and therefore that speech disorders in PD can predict FOG deficits within the horizon of some years. The aim of this study is to employ a complex quantitative analysis of the phonation, articulation and prosody in PD patients in order to identify the relationship between HD and FOG, and establish a mathematical model that would predict FOG deficits using acoustic analysis at baseline. We enrolled 75 PD patients who were assessed by 6 clinical scales including the Freezing of Gait Questionnaire (FOG-Q). We subsequently extracted 19 acoustic measures quantifying speech disorders in the fields of phonation, articulation and prosody. To identify the relationship between HD and FOG, we performed a partial correlation analysis. Finally, based on the selected acoustic measures, we trained regression models to predict the change in FOG during a 2-year follow-up. We identified significant correlations between FOG-Q scores and the acoustic measures based on formant frequencies (quantifying the movement of the tongue and jaw) and speech rate. Using the regression models, we were able to predict a change in particular FOG-Q scores with an error of between 7.4 and 17.0 %. This study is suggesting that FOG in patients with PD is mainly linked to improper articulation, a disturbed speech rate and to intelligibility. We have also proved that the acoustic analysis of HD at the baseline can be used as a predictor of the FOG deficit during 2 years of follow-up. This knowledge enables researchers to introduce new cognitive systems that predict gait difficulties in PD patients.

The Relationship Between Speech Production and Speech Perception Deficits in Parkinson's Disease

PURPOSE

This study investigated the possible relationship between hypokinetic speech production and speech intensity perception in patients with Parkinson's disease (PD).

METHOD

Participants included 14 patients with idiopathic PD and 14 matched healthy controls (HCs) with normal hearing and cognition. First, speech production was objectified through a standardized speech intelligibility assessment, acoustic analysis, and speech intensity measurements. Second, an overall estimation task and an intensity estimation task were addressed to evaluate overall speech perception and speech intensity perception, respectively. Finally, correlation analysis was performed between the speech characteristics of the overall estimation task and the corresponding acoustic analysis. The interaction between speech production and speech intensity perception was investigated by an intensity imitation task.

RESULTS

Acoustic analysis and speech intensity measurements demonstrated significant differences in speech production between patients with PD and the HCs. A different pattern in the auditory perception of speech and speech intensity was found in the PD group.

CONCLUSIONS

Auditory perceptual deficits may influence speech production in patients with PD. The present results suggest a disturbed auditory perception related to an automatic monitoring deficit in PD.

Role of the Internal Superior Laryngeal Nerve in the Motor Responses of Vocal Cords and the Related Voice Acoustic Changes

BACKGROUND

Repeated efforts by researchers to impose voice changes by laryngeal surface electrical stimulation (SES) have come to no avail. This present pre-experimental study employed a novel method for SES application so as to evoke the motor potential of the internal superior laryngeal nerve (ISLN) and create voice changes.

METHODS

Thirty-two normal individuals (22 females and 10 males) participated in this study. The subjects were selected from the students of Iran University of Medical Sciences in 2014. Two monopolar active electrodes were placed on the thyrohyoid space at the location of the ISLN entrance to the larynx and 1 dispersive electrode was positioned on the back of the neck. A current with special programmed parameters was applied to stimulate the ISLN via the active electrodes and simultaneously the resultant acoustic changes were evaluated. All the means of the acoustic parameters during SES and rest periods were compared using the paired t-test.

RESULTS

The findings indicated significant changes (P=0.00) in most of the acoustic parameters during SES presentation compared to them at rest. The mean of fundamental frequency standard deviation (SD F0) at rest was 1.54 (SD=0.55) versus 4.15 (SD=3.00) for the SES period. The other investigated parameters comprised fundamental frequency (F0), minimum F0, jitter, shimmer, harmonic-to-noise ratio (HNR), mean intensity, and minimum intensity.

CONCLUSION

These findings demonstrated significant changes in most of the important acoustic features, suggesting that the stimulation of the ISLN via SES could induce motor changes in the vocal folds. The clinical applicability of the method utilized in the current study in patients with vocal fold paralysis requires further research.

Transducer-based evaluation of tremor

The International Parkinson and Movement Disorder Society established a task force on tremor that reviewed the use of transducer-based measures in the quantification and characterization of tremor. Studies of accelerometry, electromyography, activity monitoring, gyroscopy, digitizing tablet-based measures, vocal acoustic analysis, and several other transducer-based methods were identified by searching PubMed.gov. The availability, use, acceptability, reliability, validity, and responsiveness were reviewed for each measure using the following criteria: (1) used in the assessment of tremor; (2) used in published studies by people other than the developers; and (3) adequate clinimetric testing. Accelerometry, gyroscopy, electromyography, and digitizing tablet-based measures fulfilled all three criteria. Compared to rating scales, transducers are far more sensitive to changes in tremor amplitude and frequency, but they do not appear to be more capable of detecting a change that exceeds random variability in tremor amplitude (minimum detectable change). The use of transducer-based measures requires careful attention to their limitations and validity in a particular clinical or research setting. © 2016 International Parkinson and Movement Disorder Society.

Uso do programa MDVP em diferentes contextos: revisão de literatura

Resumo:Este estudo tem como objetivo descrever, a partir de revisão de literatura, a confiabilidade da análise acústica utilizando o Multi Dimensional Voice Program,comparação de suas medidas com outros programas de análise acústica; caracterização de vozes de diferentes grupos; e sua utilização para verificar os efeitos e eficácia de diferentes procedimentos terapêuticos. Realizou-se levantamento bibliográfico que priorizaram estudos dos últimos cinco anos, incluindo-se artigos cujo objetivo estivesse de acordo com o interesse da presente revisão. A pesquisa foi realizada nos bancos de dados das bases Lilacs, BIREME, PubMed, MedLine, Scielo e Google Schoolar, por meio dos descritores acoustic, speech acoustics e voice. As medidas mais utilizadas são frequência fundamental, jitter, shimmer e proporção harmônico-ruído. As medidas de tremor não apresentam boa confiabilidade. As medidas mais consistentes que apresentam alta concordância com outros programas de análise acústica são as relacionadas com a frequência fundamental. Diversos estudos buscam caracterizar diferentes tipos de vozes tais como as de sujeitos sem alterações vocais de ambos os sexos, buscando estabelecer parâmetro de normalidade para diferentes grupos populacionais. Além disso, alguns estudos caracterizam vozes com diferentes distúrbios. A análise acústica é um recurso objetivo e necessário na avaliação de pacientes com distúrbio vocal e, principalmente, na comparação de diversos tipos de tratamento.

Voice tremor: what we know and what we do not know

PURPOSE OF REVIEW

Voice tremor is a feature of many neurological conditions. Historically, clinical evaluation of voice tremor has relied on auditory-perceptual evaluation. We review developments in understanding of voice tremor that advocate additional approaches (acoustic, fibreoptic nasolaryngoscopic examination) to evaluation and stress the contribution from multiple sites in the speech mechanism to perceived tremor.

RECENT FINDINGS

An isolated focus on the speech signal does not identify the source/s of tremor. Structures in the pharynx and larynx can be important sources of perceived voice tremor. In addition to a sustained vowel phonatory task for evaluation, fibreoptic nasolaryngoscopic examination is recommended to observe tremor behaviour in different anatomic sites using different speech tasks; acoustic analysis is recommended to quantify tremor and enhance understanding of underlying mechanisms. Tremor measures (rate, periodicity, magnitude of frequency and amplitude tremor) have proved useful in differentiating speakers with tremor from normal speakers. Differentiating between tremor aetiologies is proving more challenging. The investigation of a conceptual model of voice tremor to understand the effect that oscillations in different parts of the speech mechanism have on the speech signal is an important development in the field.

SUMMARY

A sustained phonatory vowel task with fibreoptic nasolaryngoscopic examination of pharyngeal and laryngeal musculature, supplemented by acoustic measures, is currently recommended for clinical identification, quantification and characterization of voice tremor.

Nonlinear vocal fold dynamics resulting from asymmetric fluid loading on a two-mass model of speech

Nonlinear vocal fold dynamics arising from asymmetric flow formations within the glottis are investigated using a two-mass model of speech with asymmetric vocal fold tensioning, representative of unilateral vocal fold paralysis. A refined theoretical boundary-layer flow solver is implemented to compute the intraglottal pressures, providing a more realistic description of the flow than the standard one-dimensional, inviscid Bernoulli flow solution. Vocal fold dynamics are investigated for subglottal pressures of 0.6 < p(s) < 1.5 kPa and tension asymmetries of 0.5 < Q < 0.8. As tension asymmetries become pronounced the asymmetric flow incites nonlinear behavior in the vocal fold dynamics at subglottal pressures that are associated with normal speech, behavior that is not captured with standard Bernoulli flow solvers. Regions of bifurcation, coexistence of solutions, and chaos are identified.

Voice disorders in children with classic galactosemia

Children with classic galactosemia are at risk for motor speech disorders resulting from disruptions in motor planning and programming (childhood apraxia of speech or CAS) or motor execution (dysarthria). In the present study of 33 children with classic galactosemia, 21% were diagnosed with CAS, 3% with ataxic dysarthria, and 3% with mixed CAS-dysarthria. Voice disorders due to laryngeal insufficiency were common in children with dysarthria and co-occurred with CAS. Most (58%) of the children with classic galactosemia had decreased respiratory-phonatory support for speech, and 33% had disturbed vocal quality that was indicative of cerebellar dysfunction. Three children, two diagnosed with CAS and one not diagnosed with a motor speech disorder, had vocal tremors. Treatment of voice dysfunction in neurogenic speech disorders is discussed.