Acoustic and perceptual characteristics of voice tremor: A systematic review

Voice tremor (VT) is one of the characteristics of essential tremor (ET). This study was designed to describe the group and phonatory characteristics of classic ET patients with VT. This retrospective case-control study compared classic ET patients with age and sex-matched controls. The ET population was subgrouped based on auditory perceptual voice analysis. Electroglottography and acoustic voice samples obtained from both groups were analyzed for contact quotient (CQ) and multidimensional voice program parameters, i.e., fundamental frequency (F0), perturbation, noise, and tremor parameters. The CQ, F0, perturbation, noise, and tremor characteristics significantly increased from the moderate VT group to the severe VT group. The CQ, F0, and noise characteristics reflected the vocal folds' functionality. The perturbation and tremor parameters variation were reasoned considering the tremor-related changes occurring in the laryngeal, vocal tract, and expiratory muscles in patients with ET. Thus, phonatory analysis may help in monitoring the progression of ET.

<p>Background: Vocal tremor affects over half a million Americans. Tremor can affect structures within the respiratory, laryngeal, velopharyngeal, or oral regions (Critchley, 1949). No study has related the of tremor severity in structures in all four of these regions to the severity of vocal tremor. Purpose: The purpose of this study was (a) to describe the distribution and severity of tremor throughout the vocal tract and (b) to relate that to the severity of the voice tremor. We hypothesized that tremor would be widespread throughout the vocal tract, but most prevalent in the larynx, specifically in the true vocal folds. Additionally, we expected vocal tremor severity to be directly related to the distribution and severity of tremor in structures of the vocal tract. Method: Twenty adults with vocal tremor and two age-matched controls participated in the study. Two judges, experienced in assessment of laryngeal movement disorders, rated the tremor severity in each of 15 structures during sustained /i/, /s/, /h/, and rest breathing, and the severity of the voice tremor during sustained /i/, /s/, and /h/. Results: A novel finding of this study was the identification of distribution and severity of tremor in vocal tract structures associated with mild, moderate, and severe vocal tremor. Participants with mild voice tremor tended to show tremor limited to structures of the larynx, and in some cases, the velopharynx, and on average, had three structures affected (most commonly true vocal folds, supraglottic structures, and hypopharynx). Participants with moderate voice tremor tended to show tremor in the larynx and velopharynx, and on average, had five structures affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical laryngeal movement, and some other velar, oral, or respiratory structure). Those with severe voice tremor showed tremor in the larynx, velopharynx, and beyond and on average, had eight structures affected (most commonly true vocal folds, supraglottic structures, hypopharynx, vertical laryngeal movement, anterior and lateral chest movement, velum, and jaw). A second novel finding, obtained through regression analyses, was that tremor severity of the supraglottic structures and vertical laryngeal movement contributed the most to the voice tremor severity during sustained phonation (r=0.77, F=16.17, p<0.0001). A strong positive correlation (r=0.72) was found between the Tremor Index, a composite value of the distribution and severity of structural tremor, and the severity of the voice tremor during sustained phonation. The correlation between the severity of tremor in the true vocal folds and the voice tremor was moderate (r=0.46). Mean voice tremor severity was greater in participants over age 75 (mean=2.25) than those between 66 and 75 years (mean=1.5) and under age 65 (mean=1.8). Mean Tremor Index, was greater in participants over age 65 (mean TI=68) than those under age 65 (mean=41). In this group of 20 participants, laryngeal/hypopharyngeal structures were most frequently (95%) and severely (rated 1.7 out of 3) affected, followed by velopharyngeal (40% occurrence, 1.3 severity), respiratory (40% occurrence, 1.1 severity), and oral (40% occurrence, 1.0 severity) regions during sustained phonation. Tremor was also identified more often and with greater severity in the larynx for sustained /s/ (70% occurrence, 1.7 severity), /h/ (40% occurrence, 1.7 severity), and rest breathing (45% occurrence, 1.6 severity) than other regions. During the voiceless and rest breathing tasks, the greatest tremor severity was noted in the true vocal folds. Conclusion: Evaluation of the distribution and severity of tremor may be useful in guiding behavioral and medical treatment of voice tremor and for providing prognostic information regarding response to laryngeal botulinum toxin injection.</p>

Acoustic spectral analysis has been used to describe voice tremor with some success, but no feature distinguishing pathological from normal tremor has been clearly identified. To assist in monitoring voice tremor associated with neurological diseases, objective and quantifiable measures that can distinguish between normal and pathological tremor are desired. This study explored the plausibility of using airflow and acoustic signals to quantify the frequency and amplitude of voice tremor and potentially to distinguish pathological from normal tremor. Subjects were 10 individuals with pathological tremor, most of them individuals with Parkinson's disease, and 10 gender and age-matched individuals with no voice disorder. Simultaneous acoustic and airflow signals were recorded during sustained vowel phonation. The acoustic intensity contours and the airflow signals were submitted to spectral analysis. A peak prominence ratio, defined as the ratio of the spectral peak energy to the overall signal energy, was calculated for each spectral peak below 30 Hz. For each subject, the 6 spectral peaks with the highest peak prominence ratios were selected. Frequency values of the 6 selected acoustic or airflow spectral peaks failed to distinguish tremor group from control group. Peak prominence ratios of the 6 selected acoustic spectral peaks were significantly higher for tremor group than for control group. Although spectral analysis of airflow signals was not useful in differentiating tremor group from control group, acoustic intensity contours and airflow time waveforms were highly and positively correlated in more tremor subjects (90%) than control subjects (40%). This finding suggests that the relationship between acoustic intensity contours and airflow time waveforms may reflect the presence and the source of voice tremor.

Background: Voice tremor (VT) is the involuntary and rhythmical phonatory instability of the voice. Recent findings suggest that unilateral deep brain stimulation of the ventral intermediate nucleus (Vim-DBS) can sometimes be effective for VT. In this exploratory analysis, we investigated the effect of Vim-DBS on VT and tested the hypothesis that unilateral thalamic stimulation is effective for patients with VT. Methods: Seven patients with VT and previously implanted bilateral Vim-DBS were enrolled in the study. Each patient was randomized and recorded performing sustained phonation during the following conditions: left thalamic stimulation, right thalamic stimulation, bilateral thalamic stimulation (Bil-ON), and no stimulation (Bil-OFF). Perceptual VT ratings and an acoustic analysis to find the rate of variation of the fundamental frequency measured by the standard deviation of the pitch (f0SD) were performed in a blinded manner. For the purposes of this study, a “dominant” side was defined as one with more than twice as much reduction in VT following Vim-DBS compared to the contralateral side. The Wilcoxon signed-rank test was performed to compare the effect of the dominant side stimulation in the reduction of VT scores and f0SD. The volume of activated tissue (VAT) of the dominant stimulation side was modelled against the degree of improvement in VT to correlate the significant stimulation cluster with thalamic anatomy. Finally, tractography analysis was performed to analyze the connectivity of the significant stimulation cluster. Results: Unilateral stimulation was beneficial in all 7 patients. Five patients clearly had a “dominant” side with either benefit only seen following stimulation of one side or more than twice as much benefit from one side compared to the other. Two patients had similar benefit with unilateral stimulation from either side. The Wilcoxon paired test showed significant differences between unilateral dominant and unilateral nondominant stimulation for VT scores (p = 0.04), between unilateral dominant and Bil-OFF (p = 0.04), and between Bil-ON and unilateral nondominant stimulation (p = 0.04). No significant differences were found between Bil-ON and unilateral dominant condition (p = 0.27), or between Bil-OFF and unilateral nondominant (p = 0.23). The dominant VAT showed that the significant voxels associated with the best VT control were located in the most ventral and medial part of the Vim nucleus and the ventralis caudalis anterior internus nucleus. The connectivity analysis showed significant connectivity with the cortical areas of the speech circuit. Conclusions: Unilateral dominant-side thalamic stimulation and bilateral thalamic stimulation were equally effective in reducing VT. Nondominant unilateral stimulation alone did not significantly improve VT.

Thalamic Deep Brain Stimulation for Essential Tremor Also Reduces Voice Tremor

Quality of Life before Hyperhidrosis Treatment as a Predictive Factor for Oxybutynin Treatment Outcomes in Palmar and Axillary Hyperhidrosis

BackgroundThere is a need for accurate quantitative measures of speech in Huntington’s disease that can be used for home and in-clinic assessment. Mobile devices provide an easy-to-use, low-cost alternative to...

Voice Tremor in Parkinson's Disease: An Acoustic Study

Fifteen patients, 13 women and 2 men, with a mean age of 72.7 years (56 to 86 years) and a clinical diagnosis of essential voice tremor, were treated with botulinum injections to the thyroarytenoid muscles, and in some cases, to the cricothyroid or thyrohyoid muscles. Evaluations were based on subjective judgments by the patients, and on perceptual and acoustic analysis of voice recordings. Subjective evaluations indicated that the treatment had a beneficial effect in 67% of the patients. Perceptual evaluations showed a significant decrease in voice tremor during connected speech (p < .05). Acoustic analysis showed a nearly significant decrease in the fundamental frequency variations (p = .06) and a significant decrease in fundamental frequency during sustained vowel phonation (p < .01 ). The results of perceptual evaluation coincided most closely with the subjective judgments. It was concluded that the treatment was successful in 50% to 65% of the patients, depending on the method of evaluation.

Cases diagnosed as essential voice tremor were studied by (1) clinical statistics and (2) acoustic analytical assessments.(1) Patients with this disorder accounted for 0.06 % of the overall new outpatient population. Among 20 patients with essential voice tremor studied, there were more women than men, and patients with onset of the illness in their sixties were most frequent.(2) Sound spectrographic samples of the five vowels were analyzed with respect to frequency of voice tremor, fluctuation of fundamental frequency, PPQ, APQ, Jitter % and Shimmer %. Analysis revealed significant differences in frequency of voice tremor and APQ between /a/ and /u/, thus indicating that vocal symptoms vary for each vowel.To explore the effect of acoustic impedance on these acoustic parameters, experiments were performed using three types of cylinders differing in shape of the aperture. The results of the experiment showed that the frequency of voice tremor is lower at a larger acoustic impedance. The findings also demonstrated that acoustic factors have a bearing on the characteristics of essential voice tremor.

<strong>Background:</strong> Although voice tremor is one of the most commonly noted clinical features of essential tremor (ET), there are nearly no published data on the handicap associated with it. <strong>Methods:</strong> The Voice Handicap Index (VHI) was self-administered by participants enrolled in a research study at Columbia University Medical Center. The VHI quantifies patients’ perceptions of handicap due to voice difficulties. Data from 98 ET cases were compared with data from 100 controls and 85 patients with another movement disorder (Parkinson’s disease, PD). <strong>Results:</strong> Voice tremor was present on examination in 25 (25.5%) ET cases; 12 had mild voice tremor (ET_{Mild VT}) and 13 had marked voice tremor (ET_{Marked VT}). VHI scores were higher in ET cases than controls (p=0.02). VHI scores among ET_{Marked VT} were similar to those of PD cases; both were significantly higher than controls (pMarked VT, with values that were similar to those observed in PD. <strong>Discussion:</strong> The voice handicap associated with ET had multiple (i.e., physical, functional, and emotional) dimensions. Moreover, ET cases with marked voice tremor on examination had a level of self-reported voice handicap that was similar to that observed in patients with PD.

This study investigated the relationship between quality of life (QoL) and health-related quality of life (HRQoL) and assessed factors other than health that contribute to differences in QoL in young males with Duchenne muscular dystrophy (DMD). In this cross-sectional study, QoL and HRQoL measures were completed by 98 parents and 85 children. The Quality of My Life (QoML) questionnaire measured QoL and HRQoL as single-items, and the Pediatric Quality of Life 4.0 Generic Core (PedsQL) questionnaire was used as a multidimensional measure of HRQoL. Simple regression was used to examine the relationship between single-item measures of HRQoL and QoL. Multivariable regression was used to investigate factors that may contribute to difference in QoL and HRQoL. While ratings of QoL and HRQoL were significantly correlated with one another, HRQoL only accounted for 21% and 44% of the variability in QoL by child- and parent-reports respectively. None of the factors measured contributed ratings of the child's QoL to be much higher than HRQoL. QoL and HRQoL are related but distinct constructs as rated by children with DMD and their parents. Further research is needed to elucidate factors outside HRQoL that contribute to QoL. Quality of life (QoL) and health-related quality of life are distinct concepts rated by young males with Duchenne muscular dystrophy (DMD) and their parents. Factors outside of 'health' contribute to overall QoL in the paediatric population with DMD. This article's abstract has been translated into Spanish and Portuguese. Follow the links from the abstract to view the translations.

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. 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. 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.

Patients with voice tremor present with shaking voice which has a frequency of 4-5 Hz in their vocal tract. In most of cases, voice tremor is refractory to conservative treatment such as medication or voice therapy and the symptoms may affect a patient’s quality of life. We experienced a case of voice tremor accompanied by essential tremor of the upper extremities who was treated with bilateral thalamic deep brain stimulation (DBS). The results of an acoustic analysis and laryngeal endoscopic findings showed a partial improvement following unilateral DBS and complete improvement following bilateral DBS. FTRI, Fatr, ATRI, Jitter, Shimmer, vF0, vAm, NHR, sPPQ and sAPQ seemed to be useful parameters of voice tremor. The results suggest that the indication of DBS should be discussed for patients severely affected by voice tremor after considering the patient’s age, accompanying symptoms, backgrounds, occupation and needs.

Tremor is an involuntary movement characterized by a rhythmic oscillation around a fixed point or trajectory. It can be classified based on its clinical features or underlying cause. Tremor was the first approved indication for deep brain stimulation (DBS) in the United States. Essential tremor (ET) is the most common movement disorder. These patients typically suffer from tremor of the hands and arms, and about 40% suffer from head tremor and 20% from voice tremor. Most candidates for functional neurosurgery have severe action or postural tremor that impairs function and quality of life to the extent that the risks, costs, and inconvenience of DBS treatment are justified. Unilateral procedures are commonly performed, although bilateral procedures should be considered when limb tremor is severe bilaterally or when head, voice, or trunk tremor causes significant disability. One reason for initially pursuing unilateral DBS for control of tremor in the dominant hand is that many patients will not require repeat surgery for the nondominant side despite residual tremor on that side. Many centers have developed a staged approach to DBS for ET that allows time to pass between the two stages; this can facilitate recovery and potentially diminish the negative consequences associated with a second procedure.