Parkinsonian Speech and Voice Quality: Assessment and Improvement

Parkinson’s disease (PD) is the second most common neurodegenerative disease. Statistics show that nearly 90% of people impaired with PD develop voice and speech disorders. Speech production impairments in PD subjects typically result in hypophonia and consequently, poor speech signal-to-noise ratio (SNR) in noisy environments and inferior speech intelligibility and quality. Assessment, monitoring, and improvement of the perceived quality and intelligibility of Parkinsonian voice and speech are, therefore, paramount. In the first study of this thesis, the perceived quality of sustained vowels produced by PD patients was assessed through objective predictors. Subjective quality ratings of sustained vowels were collected from 51 PD patients, on and off the Levodopa medication, and 7 control subjects. Features extracted from the sustained vowel recordings were combined using linear regression (LR) and support vector regression (SVR). An objective metric that combined linear prediction and harmonicity features resulted in a high correlation of 0.81 with subjective ratings, higher than the performance reported in the literature. The second study focused on the prediction of amplified Parkinsonian speech quality. Speech amplifiers are used by PD patients to counteract hyperphonia. To benchmark the amplifier performance, subjective ratings of the quality of speech samples from 11 PD patients and 10 control subjects using 7 different speech amplifiers in different background noise conditions were collected. Objective quality predictors were then developed in combination with machine learning algorithms such as deep learning (DL). It was shown that the speech amplifiers differentially affect Parkinsonian speech quality and that the composite objective metric resulted in a correlation of 0.85 with subjective speech quality ratings. In the third study, a new signal-to-noise feedback (SNF) device was designed and developed to help PD patients control their speech SNR, intelligibility, and quality. The proposed SNF device contained dual ear-level microphones for estimating the speech SNR, a throat accelerometer for reliable voice activity detection, and visual/auditory alarms when the produced speech was below a certain threshold. Performance evaluation of this device in noisy environments demonstrated significant improvements in speech SNR, perceived intelligibility, and predicted quality, especially in high background noise levels

The Effect of Formant Measurement Methods on Vowel Space in Patients with Parkinson\u27s Disease Before and After Voice Treatment

LSVT-LOUD® has been shown to improve phonatory quality in patients with PD. Previous studies have shown an increase in vowel space area following treatment, but questions remain regarding possible methodological issues in interaction with phonatory factors. This study addresses these questions by comparing multiple formant measurment methods and vowel space metrics. Ten participants were recorded on two separate days before and after treatment. Formants were measured using a human-guided reference (dubbed \u27HGIM\u27), LPC, and two forms of cepstrally-liftered spectrum. Multiple vowel space metrics including the vowel articulation index, F2i/F2u, area of the vowel quadrilateral, and vowel formant dispersion utilized both lax and corner vowels to explore vowel space changes. Analysis revealed no significant change in vowel space following LSVT. High variability in LPC with a fixed coefficient was noted. These results do not support previous claims of increased vowel space but suggest that formant measurement methods may influence results

Development of a Torque-Based Device for the Quantification of Arm Rigidity in Patients with Parkinson’s Disease

Parkinsonian rigidity is caused by the inability of the muscles to relax and extend properly, due to reduced dopamine levels and often begins on one side of the body before spreading contralaterally. The current standard for determining joint rigidity in a clinical setting is a test completed by the clinician based on the feel of the relaxed wrist and elbow joints as they are passively flexed and extended and a series of ordinal rating scales, the Movement Disorder Society’s – Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), Hoehn and Yahr Scale (H&Y), and Parkinson’s Disease Questionnaire-39 (PDQ-39). These methods are used to determine the severity of the patient’s disease and the impact it has on their quality of life, but they lack objectivity and do not differentiate between individual symptoms. We present a torque-based device to objectively quantify rigidity in a PD patient’s arm. The device employs a servo motor-shaft assembly, connected to a rigid forearm sling, and controlled by a computer to passively flex and extend the elbow joint laterally. Two individuals were used for preliminary results in lieu of the patient restrictions due to COVID-19. A sine, ramp, and random (sine-like) stimuli were used on each person during a relaxed phase, and a co-contracted or clenched-fist phase. A torque transducer and potentiometer measured the torque and position with respect to time while angle of rotation, acceleration, and velocity of the shaft were monitored simultaneously to ensure safety. Results showed that the magnitude of rigidity was greater during co-contraction than during relaxation indicating that rigidity can be objectively measured using this device. Quantifying joint rigidity will allow for a better understanding of the mechanisms of rigidity in Parkinson’s and other movement disorders

The effect of multitalker background noise on speech intelligibility in Parkinson\u27s disease and controls

This study investigated the effect of multi-talker background noise on speech intelligibility in participants with hypophonia due to Parkinson’s disease (PD). Ten individuals with PD and 10 geriatric controls were tested on four speech intelligibility tasks at the single word, sentence, and conversation level in various conditions of background noise. Listeners assessed speech intelligibility using word identification or orthographic transcription procedures. Results revealed non-significant differences between groups when intelligibility was assessed in no background noise. PD speech intelligibility decreased significantly relative to controls in the presence of background noise. A phonetic error analysis revealed a distinct error profile for PD speech in background noise. The four most frequent phonetic errors were glottal-null, consonant-null in final position, stop place of articulation, and initial position cluster-singleton. The results demonstrate that individuals with PD have significant and distinctive deficits in speech intelligibility and phonetic errors in the presence of background noise

The Effect of Breathy and Strained Vocal Quality on Vowel Perception

INTRODUCTION: Research into speech intelligibility in dysarthria historically focuses on articulation deficits. However, voice quality deficits associated with motor speech disorders may also impact speech perception. This study investigates how breathy and strained vocal quality affects vowel identification and ratings of vowel goodness. METHODS: A healthy speaker recorded vowels with normal, simulated breathy and simulated strained voice quality. Acoustic, physiologic, and perceptual measures confirmed the presence of the desired voice deficits. 16 volunteer listeners participated in three perceptual tasks: vowel identification, vowel goodness ratings, and voice quality ratings. RESULTS: In the voice quality rating task, listeners detected voice quality deficits with ease. Breathy and strained stimuli were rated as significantly poorer in voice quality than normal stimuli. The voice quality deficits did not appear to impact vowel identification: identification accuracy for all three sets was high (95% and above) and scores did not differ significantly across the three sets of vowels. Listener judgments of vowel goodness, however, were affected by voice quality. Breathy and strained vowels were rated as significantly poorer than normal vowels. In addition, listeners needed more time to rate the articulatory goodness of the disordered stimuli and replayed them more often while making their goodness judgments. CONCLUSION: Simulation of voice quality deficits appears to be a valid way of assessing the impact of speech factors beyond articulation on the perception of disordered speech. Stimuli with simulated breathiness and strain were rated as poorer in voice quality than normally voiced vowels, indicating that voice quality is salient to listeners. Although identification accuracy was not affected by voice quality deficits, breathy and strained vowels were judged as poorer in articulatory goodness than normally voiced vowels. Abnormal voice quality appeared to interfere with listener judgments of the articulatory goodness of vowels. Voice quality deficits associated with dysarthria may affect speech perception by causing increased listener effort even if speech intelligibility is not directly affected. Further study of the effect of voice quality in more realistic listening conditions (e.g., in noise) with more complex speech stimuli (e.g., sentences or conversation) will help determine the need for phonatory treatment of dysarthric speech

Characterizing the Effects of High-intensity Exercise on Balance and Gait under Dual-task Conditions in Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disorder, characterized by four cardinal motor symptoms including bradykinesia, tremor, rigidity, and postural instability, and non-motor symptoms including cognitive impairment. Daily activities, such as walking and maintaining balance, are impacted due to impairments in motor function, and are further exacerbated with the addition of cognitive loading, or dual-tasking (DT). High-intensity exercise has demonstrated centrally-mediated improvements of PD symptoms, with additional positive effects on overall health. The goal of this project was to identify changes in dynamic balance recovery and gait function under conditions with and without increased cognitive load after a high-intensity exercise intervention in a PD population. Participants included people with PD who completed an eight-week cycling intervention (PDE), people with Parkinson’s disease who did not complete the intervention (PDC), and healthy age-matched controls (HC), with 14 subjects per group. In Aim 1, while participants underwent a series of destabilizing balance tests, the time taken to regain balance and the center of pressure movement during balance recovery were measured. The PDE group demonstrated greater improvement in balance recovery after exercise compared with the PDC group. In Aim 2, participants completed a series of gait and cognitive tasks, both separately and concurrently. Outcome measures included spatiotemporal and kinematic gait parameters of the lower and upper extremities. The PDE group demonstrated significant improvement in gait measures and DT abilities compared to PDC, while no changes were found in cognitive function for any group. The standard clinical methods of measuring motor function can be subjective, and may not capture subtle motor characteristics. Force plate and motion-capture technologies can provide detailed, objective outcome data, therefore improving the understanding of how exercise affects motor symptoms of Parkinson’s disease. The Motek Computer Assisted Rehabilitation Environment (CAREN) system at the Cleveland Clinic was used to create the testing environment and for data collection. These results of this project suggest global changes in motor function demonstrated by changes in balance recovery and lower and upper extremity gait function. Quantitative gait analysis has shown to be an important metric in assessing effectiveness of an exercise intervention in PD

Parkinson's disease in the elderly patient: an objective assessment of night-time movement and daytime bradykinesia

The disability caused by Parkinson's disease in old age is difficult to quantify and the response to medication may be small. Consequently, emphasis has been placed on objective methods of assessment of night-time and daytime mobility in the following work. The size and frequency of movement during sleep were recorded using a bed movement monitor. Mean move size was reduced in those with either Parkinson's disease or a low cognitive function score. When both these factors coexisted the resultant reduction in mobility was associated with a higher prevalence of pressure sores. Furthermore, frequency of movement was inversely proportional to cognitive function score. A double-blind, placebo-controlled, cross-over study of nocturnal dosing with Sinemet-Plus in patients with Parkinson's disease was carried out. Following active treatment, there was an improvement in sleep both as assessed subjectively and by measurement of night-time mobility. Despite the long interval between dosing and morning assessment, walking time was also faster. In a further double-blind, placebo-controlled, cross-over study, a pedobarograph and a gait assessment trolley were used in a novel way to measure the effect of Sinemet-Plus on daytime bradykinesia. After active treatment, the nature of foot strike improved and the double support time was reduced. Serial plasma concentrations of levodopa and 3-0-methyldopa were measured using high-performance liquid chromatography. As duration of levodopa therapy increased there was a decrease in the area under the levodopa plasma concentration/time curve and an increase in the mean 3-0-methyldopa plasma concentration. However, no relationship was found between parameters of gait and plasma concentrations of levodopa and 3-0 methyldopa, or measurements of mean arterial blood pressure

Characterizing the Effects of High-intensity Exercise on Balance and Gait under Dual-task Conditions in Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disorder, characterized by four cardinal motor symptoms including bradykinesia, tremor, rigidity, and postural instability, and non-motor symptoms including cognitive impairment. Daily activities, such as walking and maintaining balance, are impacted due to impairments in motor function, and are further exacerbated with the addition of cognitive loading, or dual-tasking (DT). High-intensity exercise has demonstrated centrally-mediated improvements of PD symptoms, with additional positive effects on overall health. The goal of this project was to identify changes in dynamic balance recovery and gait function under conditions with and without increased cognitive load after a high-intensity exercise intervention in a PD population. Participants included people with PD who completed an eight-week cycling intervention (PDE), people with Parkinson’s disease who did not complete the intervention (PDC), and healthy age-matched controls (HC), with 14 subjects per group. In Aim 1, while participants underwent a series of destabilizing balance tests, the time taken to regain balance and the center of pressure movement during balance recovery were measured. The PDE group demonstrated greater improvement in balance recovery after exercise compared with the PDC group. In Aim 2, participants completed a series of gait and cognitive tasks, both separately and concurrently. Outcome measures included spatiotemporal and kinematic gait parameters of the lower and upper extremities. The PDE group demonstrated significant improvement in gait measures and DT abilities compared to PDC, while no changes were found in cognitive function for any group. The standard clinical methods of measuring motor function can be subjective, and may not capture subtle motor characteristics. Force plate and motion-capture technologies can provide detailed, objective outcome data, therefore improving the understanding of how exercise affects motor symptoms of Parkinson’s disease. The Motek Computer Assisted Rehabilitation Environment (CAREN) system at the Cleveland Clinic was used to create the testing environment and for data collection. These results of this project suggest global changes in motor function demonstrated by changes in balance recovery and lower and upper extremity gait function. Quantitative gait analysis has shown to be an important metric in assessing effectiveness of an exercise intervention in PD

Does voice amplification increase intelligibility in people with Parkinson's disease

Background/Aims: Patients with speech intelligibility difficulties associated with a quiet voice are often prescribed a voice amplifier. This study examined whether artificial voice amplification improved intelligibility in people with Parkinson's disease and whether there was an optimum increase that brought about best improvement. Methods: Twelve people diagnosed with Parkinson's disease (mild=4, moderate intelligibility difficulties=8) and five age-matched controls read low predictability sentences in their habitual voice. Audio recordings were digitally manipulated to create samples at +2.3 dB, +5 dB and +10 dB amplification. Listeners transcribed the recorded sentences. The percentage of words correctly identified was compared across levels of amplification and groups. Results: Participants with moderate Parkinson's disease were significantly less intelligible than controls in all conditions. Moderately, but not mildly affected participants with Parkinson's disease showed higher intelligibility in the amplified conditions, though statistically significantly only at +2.3 dB. No other significant effects of intensity or interactions with groups were found. At an individual level, some participants showed clear advantages of amplification. Conclusion: Based on results from the current participants, potential benefits of amplification cannot be promised to all people with Parkinson's disease. Nevertheless, several provisos regarding methods employed suggest the question can gainfully be pursued using broader measures to assess effects of amplification with more varied groups of people with Parkinson's disease and with other aetiologies where voice production can be an issue