Audiology and Speech Pathology - Research Publications
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ItemNo Preview AvailablePlug-and-play microphones for recording speech and voice with smart devices(KARGER, 2023-11-16)INTRODUCTION Smart devices are widely available and capable of quickly recording and uploading speech segments for health-related analysis. The switch from laboratory recordings with professional-grade microphone set ups to remote, smart device-based recordings offers immense potential for the scalability of voice assessment. Yet, a growing body of literature points to a wide heterogeneity among acoustic metrics for their robustness to variation in recording devices. The addition of consumer-grade plug-and-play microphones has been proposed as a possible solution. Our aim was to assess if the addition of consumer-grade plug-and-play microphones increase the acoustic measurement agreement between ultra-portable devices and a reference microphone. METHODS Speech was simultaneously recorded by a reference high-quality microphone commonly used in research, and by two configurations with plug-and-play microphones. Twelve speech-acoustic features were calculated using recordings from each microphone to determine the agreement intervals in measurements between microphones. Agreement intervals were then compared to expected deviations in speech in various neurological conditions. Each microphone's response to speech and to silence were characterized through acoustic analysis to explore possible reasons for differences in acoustic measurements between microphones. The statistical differentiation of two groups, neurotypical and people with Multiple Sclerosis, using metrics from each tested microphone was compared to that of the reference microphone. RESULTS The two consumer-grade plug-and-play microphones favoured high frequencies (mean centre of gravity difference ≥ +175.3Hz) and recorded more noise (mean difference in signal-to-noise ≤ -4.2dB) when compared to the reference microphone. Between consumer-grade microphones, differences in relative noise were closely related to distance between the microphone and the speaker's mouth. Agreement intervals between the reference and consumer-grade microphones remained under disease-expected deviations only for fundamental frequency (f0, agreement interval ≤0.06Hz), f0 instability (f0 CoV, agreement interval ≤0.05%) and for tracking of second formant movement (agreement interval ≤1.4Hz/millisecond). Agreement between microphones was poor for other metrics, particularly for fine timing metrics (mean pause length and pause length variability for various tasks). The statistical difference between the two groups of speakers was smaller with the plug-and-play than with the reference microphone. CONCLUSION Measurement of f0 and F2 slope were robust to variation in recording equipment while other acoustic metrics were not. Thus, the tested plug-and-play microphones should not be used interchangeably with professional-grade microphones for speech analysis. Plug-and-play microphones may assist in equipment standardization within speech studies, including remote or self-recording, possibly with small loss in accuracy and statistical power as observed in this study.
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ItemSpeech metrics, general disability, brain imaging and quality of life in multiple sclerosis(WILEY, 2021-01)BACKGROUND AND PURPOSE: Objective measurement of speech has shown promising results to monitor disease state in multiple sclerosis. In this study, we characterize the relationship between disease severity and speech metrics through perceptual (listener based) and objective acoustic analysis. We further look at deviations of acoustic metrics in people with no perceivable dysarthria. METHODS: Correlations and regression were calculated between speech measurements and disability scores, brain volume, lesion load and quality of life. Speech measurements were further compared between three subgroups of increasing overall neurological disability: mild (as rated by the Expanded Disability Status Scale ≤2.5), moderate (≥3 and ≤5.5) and severe (≥6). RESULTS: Clinical speech impairment occurred majorly in people with severe disability. An experimental acoustic composite score differentiated mild from moderate (P < 0.001) and moderate from severe subgroups (P = 0.003), and correlated with overall neurological disability (r = 0.6, P < 0.001), quality of life (r = 0.5, P < 0.001), white matter volume (r = 0.3, P = 0.007) and lesion load (r = 0.3, P = 0.008). Acoustic metrics also correlated with disability scores in people with no perceivable dysarthria. CONCLUSIONS: Acoustic analysis offers a valuable insight into the development of speech impairment in multiple sclerosis. These results highlight the potential of automated analysis of speech to assist in monitoring disease progression and treatment response.
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ItemNovel Functional MRI Task for Studying the Neural Correlates of Upper Limb Tremor(FRONTIERS MEDIA SA, 2018-07-02)Introduction: Tremor of the upper limbs is a disabling symptom that is present during several neurological disorders and is currently without treatment. Functional MRI (fMRI) is an essential tool to investigate the pathophysiology of tremor and aid the development of treatment options. However, no adequately or standardized protocols for fMRI exists at present. Here we present a novel, online available fMRI task that could be used to assess the in vivo pathology of tremor. Objective: This study aims to validate the tremor-evoking potential of the fMRI task in a small group of tremor patients outside the scanner and assess the reproducibility of the fMRI task related activation in healthy controls. Methods: Twelve HCs were scanned at two time points (baseline and after 6-weeks). There were two runs of multi-band fMRI and the tasks included a "brick-breaker" joystick game. The game consisted of three conditions designed to control for most of the activation related to performing the task by contrasting the conditions: WATCH (look at the game without moving joystick), MOVE (rhythmic left/right movement of joystick without game), and PLAY (playing the game). Task fMRI was analyzed using FSL FEAT to determine clusters of activation during the different conditions. Maximum activation within the clusters was used to assess the ability to control for task related activation and reproducibility. Four tremor patients have been included to test ecological and construct validity of the joystick task by assessing tremor frequencies captured by the joystick. Results: In HCs the game activated areas corresponding to motor, attention and visual areas. Most areas of activation by our game showed moderate to good reproducibility (intraclass correlation coefficient (ICC) 0.531-0.906) with only inferior parietal lobe activation showing poor reproducibility (ICC 0.446). Furthermore, the joystick captured significantly more tremulous movement in tremor patients compared to HCs (p = 0.01) during PLAY, but not during MOVE. Conclusion: Validation of our novel task confirmed tremor-evoking potential and reproducibility analyses yielded acceptable results to continue further investigations into the pathophysiology of tremor. The use of this technique in studies with tremor patient will no doubt provide significant insights into the treatment options.
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ItemNo Preview AvailableDeep brain stimulation wash-in and wash-out times for tremor and speech(Elsevier, 2015)Parkinson’s disease (PD) and Essential Tremor (ET) are progressive conditions with high world-wide prevalence. Deep Brain Stimulation (DBS) is an accepted therapy, yet the underlying therapeutic neurophysiological mechanisms are not well understood. We studied the wash in/out times of DBS therapy for tremor suppression and speech side-effect to gain further insight into these mechanisms and to establish guidelines for future research. Methods: After obtaining informed consent, 10 patients (ET or tremor-dominant PD) with DBS were recruited into our study from the medical registers of two neurologists. Over the course of a two hour assessment, DBS amplitude was systematically varied between 100% (therapeutic level) and 0% (DBS off) with 75% and 50% as intermediate steps. After each DBS adjustment, patients were asked to perform the following exercises: hands outstretched, finger-nose-finger, sustained vowel and reading tasks. The tasks were also performed at approximately 5 minutes and 10 minutes post-adjustment. Tremor was objectively measured using an electromagnetic tracking system and speech was recorded using a head-mounted microphone - both were analysed using in-house design software. Results: While an immediate increase in tremor severity was observed when DBS was disabled, preliminary qualitative results indicate that it may take more than 10 minutes to achieve steady-state. In contrast, we found that incremental increases in DBS achieved tremor-steady state within seconds. Speech parameters generally reached steady values within 2 minutes. Discussion: Wash in and wash out times must be taken into consideration during patient assessments, both in standard care and scientific studies. Where DBS parameters are randomised during patient assessment, at least 10 minutes must be allowed during consecutive trials to allow for wash in/out. This time can be reduced to two minutes when a systematic assessment procedure is adopted, where each subsequent trial increments DBS amplitude.
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ItemNo Preview AvailableThe influence of rate of stimulation and pulse duration on efficacy of deep brain stimulation for Essential Tremor(Elsevier, 2015)Deep brain stimulation (DBS) is used to alleviate tremor in patients diagnosed with Essential Tremor who do not respond to conventional treatments. To achieve optimal tremor suppression, a large stimulus parameter space needs to be explored. In practice, a default pulse duration and stimulation rate (generally 60 us and 130 Hz) are often chosen and current or voltage varied to determine a clinically effective setting. This study explored the effect of rate of stimulation in 5 patients with bilateral DBS stimulation to the posterior sub-thalamic area (PSA). Additionally, the effects of varying charge per pulse by varying pulse duration alone or by varying current/voltage alone were compared. In experiment 1, rate was varied using the values 20, 70, 100, 130, 150 and 210 Hz, keeping pulse duration (90 us) and current (1 patient) or voltage (4 patients) fixed. In experiment 2, rate was fixed at 130 Hz, and charge per phase was varied first by changing pulse duration between 60, 90, and 120 us, and secondly by altering current or voltage by the same ratios. Tremor severity was categorized by two experienced clinicians. Figure 1 shows the effect rate for each subject. A repeated measures ANOVA showed a significant effect of rate (p <0.001) with the 40 Hz rate producing worse tremor scores than all rates of 100 Hz and above. Two patients showed a U-shaped response with best tremor suppression between 100 and 130 Hz, whereas the remaining patients showed a trend for better tremor suppression as rate increased across the whole range. Paired t-tests showed no significant difference between changing charge per phase via pulse duration or current/voltage, although both these effects were small, leading to poor statistical power.
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ItemNo Preview AvailableObjective speech marker correlates with clinical scores in non-dysarthric MS(SAGE PUBLICATIONS LTD, 2017-10-01)Background: Reduction of brain volume occurs in clinically active disease and correlates with progressive disability in multiple Sclerosis (MS). Although dysarthria is highly prevalent in MS, it only becomes clinically relevant in advanced stages of the disease. The relationship between early sub-clinical markers of dysarthria and overall disease severity is poorly understood. Aim: To examine the relationship between an objective marker of speech performance and validated clinical scores for disease severity in non-dysarthric subjects with relapsing-remitting and secondary progressive MS. Method: An experienced neurologist scored patients according to the Expanded Disability Status Scale (EDSS) and the Scale for the Assessment and Rating of Ataxia (SARA). Acoustic analysis was used to investigate the diadochokinetic speed in “as fast as possible” repetition of the meaningless word /pa/ta/ka/. Brain images were acquired using 3 Tesla magnetic resonance. Images were automatically segmented using FreeSurfer (5.7) to determine volumes for whole brain (excluding ventricules) and cerebellum. Lesions were automatically segmented by the lesion prediction algorithm as implemented in the Lesion Segmentation Tool version 2.0.15 for SPM (Statistical Parametric Mapping software). Statistical correlations were processed in SPSS (v 23.0) controlling for age. After adjustment for multiple comparisons, a p< 0.01 was considered for statistical significance. Results: We assessed 35 MS patients with normal speech (i.e. SARA speech sub-score 0-1; age=47.7±12years; disease duration=13.2±8.4). Diadochokinetic rate (mean=5.63±0.83 syllables per second) directly correlated with EDSS (Spearman's rho=0.454, 2-tailed p=0.007; median EDSS=3.5, interquartile range=3.5) and SARA (rho=0.515, p=0.002; SARA median=9, interquartile range 11.975), but not with whole brain volume (p=0.022), lesion load (p=0.032) or cerebellar volume (p=0.037). Conclusion: Changes in acoustic markers can be detected before overt dysarthria in MS and reflect overall disease severity. Larger and longitudinal studies are needed to understand if those markers can help monitoring disease progression.
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ItemNo Preview AvailablePathophysiology of MS tremor: an fMRI study(SAGE PUBLICATIONS LTD, 2017-10)
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ItemNo Preview AvailableSubclinical speech signs correlate with MS disease severity and differentiates patients with and without clinical cerebellar dysfunction(SAGE PUBLICATIONS LTD, 2017-10-01)Background: Dysarthria is highly prevalent in Multiple Sclerosis (MS). The relationship between dysarthria, MS disease severity and other cerebellar manifestations (such as tremor) is poorly understood. Aim: To examine the relationship between objective markers of speech, disease severity and upper limb tremor in relapsing-remitting and secondary progressive MS. Method: An experienced neurologist determined A) the presence of upper limb tremor, B) the Expanded Disability Status Scale (EDSS) score and C) the degree of dysarthria (from 0, no disturbance to 4, unintelligible). We used acoustic analysis to investigate 4 speech domains: 1) stability of vocal pitch, in sustained utterance of the vowel /a/; 2) stability of loudness, in the same sustained vowel; 3) diadochokinetic speed, in fast repetition of the meaningless word /pa/ta/ka/ and 4) maximum speed of vocal tract movement (i.e. change in pharynx and mouth cavity shape), measured through change in the second formant frequency in the word “always”, from reading of the “Grandfather Passage”. After adjustment for multiple comparisons, a p< 0.0125 was considered for statistical significance. Results: We assessed 24 MS patients with upper limb tremor (47.2±12.3years, 75% female, EDSS=3.7±1.6) and 24 matched patients without tremor (51.2±10.7years, 75% female, EDSS=3.6±1.7). Clinical dysarthria (median=0, mean=0.375±0.76) moderately correlated with EDSS scores (Spearman's rho =.586, p< .001) and with syllable repetition rates (/pa/ta/ka/ rho=.561, p< .001), marginally correlated with speed of tract movement (rho=.363, p=.012), pitch stability (rho=.37, p=.011), loudness stability (rho=.37, p=.01) but not with upper limb tremor presence (p=.039). Only /pa/ta/ka/ rate correlated with EDSS (rho=.529, p< .001) and speed of tract movement differentiated tremor and non-tremor groups (2-tailed t-test p=0.002, rho=.418). Conclusion: Acoustic speech measurements correlate with MS disease severity and can differentiate overt cerebellar dysfunction. Further study is needed to understand the significance of this relationship longitudinally.
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ItemNo Preview AvailableObjective analysis of speech correlates with disease severity in Multiple Sclerosis and differentiates groups with and without upper limb tremor(SAGE PUBLICATIONS LTD, 2017-11-01)Background: Dysarthria is highly prevalent in Multiple Sclerosis. The relationship between dysarthria, MS disease severity and other cerebellar manifestations (such as tremor) is poorly understood. Objective: To examine the relationship between objective markers of speech, disease severity and upper limb tremor in relapsing-remitting and secondary progressive Multiple Sclerosis. Design Methods: An experienced neurologist determined A) the presence of upper limb tremor, B) the Expanded Disability Status Scale (EDSS) score and C) the degree of dysarthria (from 0, no disturbance to 4, unintelligible). Through acoustic analysis of speech, we investigated: 1) stability of vocal pitch, in sustained utterance of the vowel /a/; 2) stability of loudness, in the same sustained vowel; 3) diadochokinetic speed, in fast repetition of the meaningless word /pa/ta/ka/ and 4) maximum speed of vocal tract movement (i.e. change in pharynx and mouth cavity shape), measured in the word “always” (from a standard reading passage). After adjustment for multiple comparisons, p<0.0125 was considered for statistical significance. Results: We assessed 24 participants with Multiple Sclerosis and upper limb tremor (47.2±12.3years, 75% female, EDSS=3.7±1.6) and 24 matched patients with Multiple Sclerosis without tremor (51.2±10.7years, 75% female, EDSS=3.6±1.7). Clinical dysarthria scores (median=0, mean=0.375±0.76) correlated with all acoustic variables measured: diadochokinetic speed Spearman’s rho=.561 (p<.001); pitch stability rho=.37 (p=.011); loudness stability rho=.37 (p=.01); and maximum speed of vocal tract movement rho=.363 (p=.012). Diadochokinetic speed strongly correlated with EDSS (rho=.529, p<.001). Speed of vocal tract movement correlated with tremor and differentiated tremor and non-tremor groups (2-tailed t-test p=0.002, rho=.418). Conclusions: In a typically non-to-mildly dysarthric cohort, acoustic speech measurements correlate with disease severity and can differentiate overt cerebellar dysfunction in Multiple Sclerosis. Further study is needed to understand the significance of this relationship longitudinally.