Breath-group intelligibility in dysarthria: characteristics and underlying correlates

A comparative study of automatic vowel articulation index and auditory-perceptual assessments of speech intelligibility in Parkinson's disease

PURPOSE

The purpose of this study was to analyse the relationship between automatic vowel articulation index (aVAI) and direct magnitude estimation (DME) among speakers with Parkinson's disease (PD) and healthy controls. We further analysed the potential of aVAI to serve as an objective measure of speech impairment in the clinical setting.

METHOD

Speech samples from native Finnish speakers were utilised. Expert raters utilised DME to scale the intelligibility of speech samples. aVAI scores for PD speakers and healthy control speakers were analysed in relationship to DME speech intelligibility ratings and, among PD speakers, disease stage utilising nonparametric statistical analysis.

RESULT

Mean DME intelligibility ratings were lower among PD speakers compared to healthy controls. Mean aVAI scores were nearly the same between speaker groups. DME intelligibility ratings and aVAI were strongly correlated within the PD speaker group. aVAI and DME intelligibility ratings were moderately correlated with disease stage as measured by the Hoehn and Yahr scale.

CONCLUSION

aVAI was observed to be a promising tool for analysing vowel articulation in PD speakers. Further research is warranted on the application of aVAI as an objective measure of severity of speech impairment in the clinical setting, with varying patient populations and speech samples.

Effects of Age and Parkinson's Disease on the Relationship between Vocal Fold Abductory Kinematics and Relative Fundamental Frequency

PURPOSE

This study reports on two experiments to examine vocal fold abduction and its relationship with relative fundamental frequency (RFF), considering two attributes that have been shown to elicit group differences in RFF: age (Experiment 1) and Parkinson's disease (PD; Experiment 2).

METHODS

For both experiments, simultaneous acoustic and nasendoscopic recordings were collected as participants produced the utterance, /ifi/. RFF values were computed from the acoustic signal, whereas abduction duration and glottic angle at voicing offset were identified from the laryngoscopic images. In Experiment 1, 50 speakers with typical voices (18-83 years) were analyzed to examine (1A) the effects of speaker age on individual outcome measures (RFF, abduction duration, glottic angle) via Pearson's correlation coefficients, and (1B) the effects of abductory measures and age on RFF via an analysis of covariance. In Experiment 2, 20 speakers with PD and 20 matched controls were analyzed to examine (2A) the effects of group (with/without PD) on outcome measures via an analysis of variance, and (2B) the relationship of RFF with abduction duration, glottic angle, and age when considering group via an analysis of covariance.

RESULTS

Age demonstrated a significant, negative relationship with glottic angle (1A) but was not a significant factor when examining the relationship of vocal fold abduction and RFF (1B). Speaker group (with/without PD) demonstrated a significant effect on measures of RFF and abduction duration (2A) but was not a significant factor when examining the relationship of vocal fold abduction and RFF (2B).

CONCLUSIONS

RFF is sensitive to changes in vocal fold abductory patterns during devoicing, irrespective of speaker age or PD status.

No differential effects of subthalamic nucleus vs. globus pallidus deep brain stimulation in Parkinson's disease: Speech acoustic and perceptual findings

Background

Deep Brain Stimulation (DBS) in the Subthalamic Nucleus (STN) or the Globus Pallidus Interna (GPI) is well-established as a surgical technique for improving global motor function in patients with idiopathic Parkinson's Disease (PD). Previous research has indicated speech deterioration in more than 30% of patients after STN-DBS implantation, whilst speech outcomes following GPI-DBS have received far less attention. Research comparing speech outcomes for patients with PD receiving STN-DBS and GPI-DBS can inform pre-surgical counseling and assist with clinician and patient decision-making when considering the neural targets selected for DBS-implantation. The aims of this pilot study were (1) to compare perceptual and acoustic speech outcomes for a group of patients with PD receiving bilateral DBS in the STN or the GPI with DBS stimulation both ON and OFF, and (2) examine associations between acoustic and perceptual speech measures and clinical characteristics.

Methods

Ten individuals with PD receiving STN-DBS and eight individuals receiving GPI-DBS were audio-recorded reading a passage. Three listeners blinded to neural target and stimulation condition provided perceptual judgments of intelligibility and overall speech severity. Speech acoustic measures were obtained from the recordings. Acoustic and perceptual measures and clinical characteristics were compared for the two neural targets and stimulation conditions.

Results

Intelligibility and speech severity were not significantly different across neural target or stimulation conditions. Generally, acoustic measures were also not statistically different for the two neural targets or stimulation conditions. Acoustic measures reflecting more varied speech prosody were associated with improved intelligibility and lessened severity. Convergent correlations were found between UPDRS-III speech scores and perceptual measures of intelligibility and severity.

Conclusion

This study reports a systematic comparison of perceptual and acoustic speech outcomes following STN-DBS and GPI-DBS. Statistically significant differences in acoustic measures for the two neural targets were small in magnitude and did not yield group differences in perceptual measures. The absence of robust differences in speech outcomes for the two neural targets has implications for pre-surgical counseling. Results provide preliminary support for reliance on considerations other than speech when selecting the target for DBS in patients with PD.

The association between longitudinal declines in speech sound accuracy and speech intelligibility in speakers with amyotrophic lateral sclerosis

The purpose of this study was to examine how neurodegeneration secondary to amyotrophic lateral sclerosis (ALS) impacts speech sound accuracy over time and how speech sound accuracy, in turn, is related to speech intelligibility. Twenty-one participants with ALS read the Bamboo Passage over multiple data collection sessions across several months. Phonemic and orthographic transcriptions were completed for all speech samples. The percentage of phonemes accurately produced was calculated across each phoneme, sound class (i.e. consonants versus vowels), and distinctive feature (i.e. features involved in Manner of Articulation, Place of Articulation, Laryngeal Voicing, Tongue Height, and Tongue Advancement). Intelligibility was determined by calculating the percentage of words correctly transcribed orthographically by naive listeners. Linear mixed effects models were conducted to assess the decline of each distinctive feature over time and its impact on intelligibility. The results demonstrated that overall phonemic production accuracy had a nonlinear relationship with speech intelligibility and that a subset of features (i.e. those dependent on precise lingual and labial constriction and/or extensive lingual and labial movement) were more important for intelligibility and were more impacted over time than other features. Furthermore, findings revealed that consonants were more strongly associated with intelligibility than vowels, but consonants did not significantly differ from vowels in their decline over time. These findings have the potential to (1) strengthen mechanistic understanding of the physiological constraints imposed by neuronal degeneration on speech production and (2) inform the timing and selection of treatment and assessment targets for individuals with ALS.

Acoustic Predictors of Ease of Understanding in Spanish Speakers With Dysarthria Associated With Parkinson's Disease

PURPOSE

The purpose of this study was to examine selected baseline acoustic features of hypokinetic dysarthria in Spanish speakers with Parkinson's disease (PD) and identify potential acoustic predictors of ease of understanding in Spanish.

METHOD

Seventeen Spanish-speaking individuals with mild-to-moderate hypokinetic dysarthria secondary to PD and eight healthy controls were recorded reading a translation of the Rainbow Passage. Acoustic measures of vowel space area, as indicated by the formant centralization ratio (FCR), envelope modulation spectra (EMS), and articulation rate were derived from the speech samples. Additionally, 15 healthy adults rated ease of understanding of the recordings on a visual analogue scale. A multiple linear regression model was implemented to investigate the predictive value of the selected acoustic parameters on ease of understanding.

RESULTS

Listeners' ease of understanding was significantly lower for speakers with dysarthria than for healthy controls. The FCR, EMS from the first 10 s of the reading passage, and the difference in EMS between the end and the beginning sections of the passage differed significantly between the two groups of speakers. Findings indicated that 67.7% of the variability in ease of understanding was explained by the predictive model, suggesting a moderately strong relationship between the acoustic and perceptual domains.

CONCLUSIONS

Measures of envelope modulation spectra were found to be highly significant model predictors of ease of understanding of Spanish-speaking individuals with hypokinetic dysarthria associated with PD. Articulation rate was also found to be important (albeit to a lesser degree) in the predictive model. The formant centralization ratio should be further examined with a larger sample size and more severe dysarthria to determine its efficacy in predicting ease of understanding.

The efficacy of acoustic-based articulatory phenotyping for characterizing and classifying four divergent neurodegenerative diseases using sequential motion rates

Despite the impacts of neurodegeneration on speech function, little is known about how to comprehensively characterize the resulting speech abnormalities using a set of objective measures. Quantitative phenotyping of speech motor impairments may have important implications for identifying clinical syndromes and their underlying etiologies, monitoring disease progression over time, and improving treatment efficacy. The goal of this research was to investigate the validity and classification accuracy of comprehensive acoustic-based articulatory phenotypes in speakers with distinct neurodegenerative diseases. Articulatory phenotypes were characterized based on acoustic features that were selected to represent five components of motor performance: Coordination, Consistency, Speed, Precision, and Rate. The phenotypes were first used to characterize the articulatory abnormalities across four progressive neurologic diseases known to have divergent speech motor deficits: amyotrophic lateral sclerosis (ALS), progressive ataxia (PA), Parkinson's disease (PD), and the nonfluent variant of primary progressive aphasia and progressive apraxia of speech (nfPPA + PAOS). We then examined the efficacy of articulatory phenotyping for disease classification. Acoustic analyses were conducted on audio recordings of 217 participants (i.e., 46 ALS, 52 PA, 60 PD, 20 nfPPA + PAOS, and 39 controls) during a sequential speech task. Results revealed evidence of distinct articulatory phenotypes for the four clinical groups and that the phenotypes demonstrated strong classification accuracy for all groups except ALS. Our results highlight the phenotypic variability present across neurodegenerative diseases, which, in turn, may inform (1) the differential diagnosis of neurological diseases and (2) the development of sensitive outcome measures for monitoring disease progression or assessing treatment efficacy.

Speech intelligibility loss due to amyotrophic lateral sclerosis: the effect of tongue movement reduction on vowel and consonant acoustic features

The purpose of this study was to identify aspects of impaired tongue motor performance that limit the ability to produce distinct speech sounds and contribute to reduced speech intelligibility in individuals with dysarthria secondary to amyotrophic lateral sclerosis (ALS). We analyzed simultaneously recorded tongue kinematic and acoustic data from 22 subjects during three target words (cat, dog, and took). The subjects included 11 participants with ALS and 11 healthy controls from the X-ray microbeam dysarthria database (Westbury, 1994). Novel measures were derived based on the range and speed of relative movement between two quasi-independent regions of the tongue - blade and dorsum - to characterize the global pattern of tongue dynamics. These "whole tongue" measures, along with the range and speed of single tongue regions, were compared across words, groups (ALS vs. control), and measure types (whole tongue vs. tongue blade vs. tongue dorsum). Reduced range and speed of both global and regional tongue movements were found in participants with ALS relative to healthy controls, reflecting impaired tongue motor performance in ALS. The extent of impairment, however, varied across words and measure types. Compared with the regional tongue measures, the whole tongue measures showed more consistent disease-related changes across the target words and were more robust predictors of speech intelligibility. Furthermore, these whole tongue measures were correlated with various word-specific acoustic features associated with intelligibility decline in ALS, suggesting that impaired tongue movement likely contributes to reduced phonetic distinctiveness of both vowels and consonants that underlie speech intelligibility decline in ALS.

Investigating Acoustic Correlates of Intelligibility Gains and Losses During Slowed Speech: A Hybridization Approach

Purpose This exploratory study sought to identify acoustic variables explaining rate-related variation in intelligibility for speakers with dysarthria secondary to multiple sclerosis. Method Seven speakers with dysarthria due to multiple sclerosis produced the same set of Harvard sentences at habitual and slow rates. Speakers were selected from a larger corpus on the basis of rate-related intelligibility characteristics. Four speakers demonstrated improved intelligibility and three speakers demonstrated reduced intelligibility when rate was slowed. A speech analysis resynthesis paradigm termed hybridization was used to create stimuli in which segmental (i.e., short-term spectral) and suprasegmental variables (i.e., sentence-level fundamental frequency, energy characteristics, and duration) of sentences produced at the slow rate were donated individually or in combination to habitually produced sentences. Online crowdsourced orthographic transcription was used to quantify intelligibility for six hybridized sentence types and the original habitual and slow productions. Results Sentence duration alone was not a contributing factor to improved intelligibility associated with slowed rate. Speakers whose intelligibility improved with slowed rate showed higher intelligibility scores for duration spectrum hybrids and energy hybrids compared to the original habitual rate sentences, suggesting these acoustic cues contributed to improved intelligibility for sentences produced with a slowed rate. Energy contour characteristics were also found to play a role in intelligibility losses for speakers with decreased intelligibility at slowed rate. The relative contribution of speech acoustic variables to intelligibility gains and losses varied considerably between speakers. Conclusions Hybridization can be used to identify acoustic correlates of intelligibility variation associated with slowed rate. This approach has further elucidated speaker-specific and individualized speech production adjustments when slowing rate.

Perceptual and Acoustic Effects of Dual-Focus Speech Treatment in Children With Dysarthria

Purpose Children with dysarthria secondary to cerebral palsy may experience reduced speech intelligibility and diminished communicative participation. However, minimal research has been conducted examining the outcomes of behavioral speech treatments in this population. This study examined the effect of Speech Intelligibility Treatment (SIT), a dual-focus speech treatment targeting increased articulatory excursion and vocal intensity, on intelligibility of narrative speech, speech acoustics, and communicative participation in children with dysarthria. Method American English-speaking children with dysarthria (n = 17) received SIT in a 3-week summer camplike setting at Columbia University. SIT follows motor-learning principles to train the child-friendly, dual-focus strategy, "Speak with your big mouth and strong voice." Children produced a story narrative at baseline, immediate posttreatment (POST), and at 6-week follow-up (FUP). Outcomes were examined via blinded listener ratings of ease of understanding (n = 108 adult listeners), acoustic analyses, and questionnaires focused on communicative participation. Results SIT resulted in significant increases in ease of understanding at POST, that were maintained at FUP. There were no significant changes to vocal intensity, speech rate, or vowel spectral characteristics, with the exception of an increase in second formant difference between vowels following SIT. Significantly enhanced communicative participation was evident at POST and FUP. Considerable variability in response to SIT was observed between children. Conclusions Dual-focus treatment shows promise for improving intelligibility and communicative participation in children with dysarthria, although responses to treatment vary considerably across children. Possible mechanisms underlying the intelligibility gains, enhanced communicative participation, and variability in treatment effects are discussed.

Using Crowdsourced Listeners' Ratings to Measure Speech Changes in Hypokinetic Dysarthria: A Proof-of-Concept Study

Purpose Interventions for speech disorders aim to produce changes that are not only acoustically measurable or perceptible to trained professionals but are also apparent to naive listeners. Due to challenges associated with obtaining ratings from suitably large listener samples, however, few studies currently evaluate speech interventions by this criterion. Online crowdsourcing technologies could enhance the measurement of intervention effects by making it easier to obtain real-world listeners' ratings. Method Stimuli, drawn from a published study by Sapir et al. ("Effects of intensive voice treatment (Lee Silverman Voice Treatment [LSVT]) on vowel articulation in dysarthric individuals with idiopathic Parkinson disease: Acoustic and perceptual findings" in Journal of Speech, Language, and Hearing Research, 50(4), 2007), were words produced by individuals who received intensive treatment (LSVT LOUD) for hypokinetic dysarthria secondary to Parkinson's disease. Thirty-six online naive listeners heard randomly ordered pairs of words elicited pre- and posttreatment and reported which they perceived as "more clearly articulated." Results Mixed-effects logistic regression indicated that words elicited posttreatment were significantly more likely to be rated "more clear." Across individuals, acoustically measured magnitude of change was significantly correlated with pre-post difference in listener ratings. Conclusions These results partly replicate the findings of Sapir et al. (2007) and demonstrate that their acoustically measured changes are detectable by everyday listeners. This supports the viability of using crowdsourcing to obtain more functionally relevant measures of change in clinical speech samples. Supplemental Material https://doi.org/10.23641/asha.12170112.

Vowel Acoustics and Speech Intelligibility in Young Adults With Down Syndrome

Purpose Speech production deficits and reduced intelligibility are frequently noted in individuals with Down syndrome (DS) and are attributed to a combination of several factors. This study reports acoustic data on vowel production in young adults with DS and relates these findings to perceptual analysis of speech intelligibility. Method Participants were eight young adults with DS as well as eight age- and gender-matched typically developing (TD) controls. Several different acoustic measures of vowel centralization and variability were applied to tokens of corner vowels (/ɑ/, /æ/, /i/, /u/) produced in common English words. Intelligibility was assessed for single-word productions of speakers with DS, by means of transcriptions from 14 adult listeners. Results Group differentiation was found for some, but not all, of the acoustic measures. Low vowels were more acoustically centralized and variable in speakers with DS than TD controls. Acoustic findings were associated with overall intelligibility scores. Vowel formant dispersion was the most sensitive measure in distinguishing DS and TD formant data. Conclusion Corner vowels are differentially affected in speakers with DS. The acoustic characterization of vowel production and its association with speech intelligibility scores within the DS group support the conclusion of motor control deficits in the overall speech impairment. Implications are discussed for effective treatment planning.

Automated Acoustic Analysis of Oral Diadochokinesis to Assess Bulbar Motor Involvement in Amyotrophic Lateral Sclerosis

Purpose The purpose of this article was to validate a novel acoustic analysis of oral diadochokinesis (DDK) in assessing bulbar motor involvement in amyotrophic lateral sclerosis (ALS). Method An automated acoustic DDK analysis was developed, which filtered out the voice features and extracted the envelope of the acoustic waveform reflecting the temporal pattern of syllable repetitions during an oral DDK task (i.e., repetitions of /tɑ/ at the maximum rate on 1 breath). Cycle-to-cycle temporal variability (cTV) of envelope fluctuations and syllable repetition rate (sylRate) were derived from the envelope and validated against 2 kinematic measures, which are tongue movement jitter (movJitter) and alternating tongue movement rate (AMR) during the DDK task, in 16 individuals with bulbar ALS and 18 healthy controls. After the validation, cTV, sylRate, movJitter, and AMR, along with an established clinical speech measure, that is, speaking rate (SR), were compared in their ability to (a) differentiate individuals with ALS from healthy controls and (b) detect early-stage bulbar declines in ALS. Results cTV and sylRate were significantly correlated with movJitter and AMR, respectively, across individuals with ALS and healthy controls, confirming the validity of the acoustic DDK analysis in extracting the temporal DDK pattern. Among all the acoustic and kinematic DDK measures, cTV showed the highest diagnostic accuracy (i.e., 0.87) with 80% sensitivity and 94% specificity in differentiating individuals with ALS from healthy controls, which outperformed the SR measure. Moreover, cTV showed a large increase during the early disease stage, which preceded the decline of SR. Conclusions This study provided preliminary validation of a novel automated acoustic DDK analysis in extracting a useful measure, namely, cTV, for early detection of bulbar ALS. This analysis overcame a major barrier in the existing acoustic DDK analysis, which is continuous voicing between syllables that interferes with syllable structures. This approach has potential clinical applications as a novel bulbar assessment.

The Effect of Tongue-Jaw Coupling on Phonetic Distinctiveness of Vowels in Amyotrophic Lateral Sclerosis

Purpose The aim of this study was to determine the relation of tongue-jaw coupling to phonetic distinctiveness of vowels in persons at different stages (i.e., early, middle, late) of bulbar motor involvement in amyotrophic lateral sclerosis (ALS) and healthy controls. Method The pattern of spatial tongue-jaw coupling was derived from 11 individuals with ALS and 11 healthy controls using the parallel factor analysis. Two articulatory components, which correspond to tongue displacement independent of the jaw (iTongue) and jaw contribution to tongue displacement (cJaw), were extracted from the composite tongue-jaw displacement. These articulatory components were correlated with F1 (i.e., height) and F2-F1 (i.e., advancement) of 4 vowels (/i/, /u/, /æ/, and /ɔ/) across all participants in each group. In addition, a comprehensive index of functional tongue-jaw coupling was derived as the ratio of cJaw/(iTongue + cJaw), and an acoustic index of vowel distortion (VowelDis) was derived to quantify the overall disease-related changes in phonetic distinctiveness of vowels. Based on these indices, disease-related changes in tongue-jaw coupling and phonetic distinctiveness of vowels were examined in individuals at the early, middle, and late stages of the disease. Results For healthy controls, both iTongue and cJaw contributed to F2-F1, while only cJaw contributed to F1. For individuals with ALS, both iTongue and cJaw contributed to F1, whereas only cJaw contributed to F2-F1. Disease-related changes in tongue-jaw coupling included (a) an overall decrease of the percent contribution of the tongue to the composite tongue-jaw displacement accompanied by an increase of percent contribution of the jaw and (b) several changes in the direction of tongue and jaw displacements occurred at different stages of the disease. These disease-related changes in tongue-jaw coupling had various impacts on phonetic distinctiveness of vowels, resulting in (a) a backward shift of front vowels and reduced front-back vowel contrasts, which occurred early and throughout the disease stages; (b) raising of all vowels during the middle stage of the disease; and (c) reduced high-low vowel contrasts during the late stage of the disease. Overall, phonetic distinctiveness of vowels deteriorated progressively throughout the disease course. Conclusions Different from healthy controls who established optimal functional coupling between the tongue and the jaw during vowel productions, individuals at the early-to-middle stages of bulbar ALS showed various adaptive changes in tongue-jaw coupling in response to the disease-related biomechanical and muscular changes in the articulators (particularly in the tongue). These adaptive changes in tongue-jaw coupling were found to be partially effective in mitigating the negative effect of articulatory involvement on phonetic distinctiveness of vowels. As the disease progressed to the late stage, such adaptations appeared to be no longer evident, resulting in a substantial overall reduction of vowel contrasts.

Predicting Speech Intelligibility Based on Spatial Tongue-Jaw Coupling in Persons With Amyotrophic Lateral Sclerosis: The Impact of Tongue Weakness and Jaw Adaptation

Purpose Motor neuron diseases, such as amyotrophic lateral sclerosis (ALS), have a devastating effect on speech muscle function that often results in severe communication deficits. Over the course of bulbar disease, tongue and jaw movements are modified, but their impact on speech is poorly understood. The aim of this study was to determine the effect of disease-related changes in tongue-jaw movement coupling on speech intelligibility in persons at different stages of bulbar ALS. Method Parallel factor analysis was used to quantify the pattern of spatial coupling between 4 semi-independent regions of the tongue and the jaw in various vowels and consonants in 10 individuals with ALS and 10 healthy individuals, respectively, from the X-Ray Microbeam database (Westbury, 1994). The relation of spatial tongue-jaw coupling to speech intelligibility was examined in individuals at the early and late stages of bulbar ALS and healthy individuals. Results Tongue movement, independent of the jaw, decreased early and progressively, which negatively impacted speech intelligibility. Jaw contribution to tongue movement was increased during the early stages of bulbar ALS compared to that of the healthy subjects, which was followed by a decrease during the late stages of bulbar ALS. The early-stage increase of jaw contribution significantly improved speech intelligibility and is thus most likely to be an adaptive strategy to mitigate the negative impact of tongue movement reductions on speech intelligibility. This adaptive strategy became unavailable during the late stages of bulbar ALS, which might accelerate intelligibility decline. Conclusions The loss of functional tongue-jaw coupling may be the critical physiological factor leading to the eventual loss of functional speech in ALS. Monitoring changes in tongue-jaw coupling may improve the prediction about the timing of speech loss and guide clinical management of dysarthria in ALS.

On the physical origin of linguistic laws and lognormality in speech

Physical manifestations of linguistic units include sources of variability due to factors of speech production which are by definition excluded from counts of linguistic symbols. In this work, we examine whether linguistic laws hold with respect to the physical manifestations of linguistic units in spoken English. The data we analyse come from a phonetically transcribed database of acoustic recordings of spontaneous speech known as the Buckeye Speech corpus. First, we verify with unprecedented accuracy that acoustically transcribed durations of linguistic units at several scales comply with a lognormal distribution, and we quantitatively justify this 'lognormality law' using a stochastic generative model. Second, we explore the four classical linguistic laws (Zipf's Law, Herdan's Law, Brevity Law and Menzerath-Altmann's Law (MAL)) in oral communication, both in physical units and in symbolic units measured in the speech transcriptions, and find that the validity of these laws is typically stronger when using physical units than in their symbolic counterpart. Additional results include (i) coining a Herdan's Law in physical units, (ii) a precise mathematical formulation of Brevity Law, which we show to be connected to optimal compression principles in information theory and allows to formulate and validate yet another law which we call the size-rank law or (iii) a mathematical derivation of MAL which also highlights an additional regime where the law is inverted. Altogether, these results support the hypothesis that statistical laws in language have a physical origin.

Shorter Sentence Length Maximizes Intelligibility and Speech Motor Performance in Persons With Dysarthria Due to Amyotrophic Lateral Sclerosis

Purpose The purpose of this study was to investigate the effect of sentence length on intelligibility and measures of speech motor performance in persons with amyotrophic lateral sclerosis (ALS) and to determine how these effects were influenced by dysarthria severity levels. Method One hundred thirty-one persons with ALS were included in this study, stratified into 4 dysarthria severity groups. All participants produced sentences from 5 to 15 words in length. Intelligibility, speaking rate, and measures of speech pausing behavior (i.e., total speech duration, total pause duration, and mean speech event duration) were measured for each sentence. Linear mixed-effects models were used to determine the effect of sentence length on speech measures for speakers at different dysarthria severity levels. Results Results showed that speech intelligibility significantly declined at longer sentence lengths only for the speakers with ALS who had more advanced dysarthria symptoms; however, speakers with mild-to-severe dysarthria showed significant declines in speaking rate and speech pausing behavior at longer sentence lengths. Conclusions Findings suggest that producing shorter sentences may help maximize intelligibility for speakers with moderate-to-severe dysarthria secondary to ALS and may be a beneficial compensatory strategy for preserving motor effort for all speakers with dysarthria secondary to ALS.

Treating Speech Movement Hypokinesia in Parkinson's Disease: Does Movement Size Matter?

Purpose

This study evaluates the effects of a novel speech therapy program that uses a verbal cue and gamified augmented visual feedback regarding tongue movements to address articulatory hypokinesia during speech in individuals with Parkinson's disease (PD).

Method

Five participants with PD participated in an ABA single-subject design study. The treatment aimed to increase tongue movement size using a combination of a verbal cue and augmented visual feedback and was conducted in 10 45-min sessions over 5 weeks. The presence of visual feedback was manipulated during treatment. Articulatory working space of the tongue was the primary outcome measure and was examined during treatment and in cued and uncued sentences pre- and posttreatment. Changes in speech intelligibility in response to a verbal cue pre- and posttreatment were also examined.

Results

During treatment, 4/5 participants showed a beneficial effect of visual feedback on tongue articulatory working space. At the end of the treatment, they used larger tongue movements when cued, relative to their pretreatment performance. None of the participants, however, generalized the effect to the uncued sentences. Speech intelligibility of cued sentences was judged as superior posttreatment only in a single participant.

Conclusions

This study demonstrated that using an augmented visual feedback approach is beneficial, beyond a verbal cue alone, in addressing articulatory hypokinesia in individuals with PD. An optimal degree of articulatory expansion might, however, be required to elicit a speech intelligibility benefit.

Acoustic properties of vowel production in Mandarin-speaking patients with post-stroke dysarthria

This study investigated the acoustic features of vowel production in Mandarin-speaking patients with post-stroke dysarthria (PSD). The subjects included 31 native Mandarin-speaking patients with PSD (age: 25–83 years old) and 38 neurologically normal adults in a similar age range (age: 21–76 years old). Each subject was recorded producing a list of Mandarin monosyllables that included six monophthong vowels (i.e., /a, i, u, ɤ, y, o/) embedded in the /CV/ context. The patients’ speech samples were evaluated by two native Mandarin speakers. The evaluation scores were then used to classify all patients into two levels of severity: mild or moderate-to-severe. Formants (F1 and F2) were extracted from each vowel token. Results showed that all vowel categories in the patients with PSD were produced with more variability than in the healthy speakers. Great overlaps between vowel categories and reduced vowel space were observed in the patients. The magnitude of the vowel dispersion and overlap between vowel categories increased as a function of the severity of the disorder. The deviations of the vowel acoustic features in the patients in comparison to the healthy speakers may provide guidance for clinical rehabilitation to improve the speech intelligibility of patients with PSD.

Acoustic Predictors of Pediatric Dysarthria in Cerebral Palsy

PURPOSE

The objectives of this study were to identify acoustic characteristics of connected speech that differentiate children with dysarthria secondary to cerebral palsy (CP) from typically developing children and to identify acoustic measures that best detect dysarthria in children with CP.

METHOD

Twenty 5-year-old children with dysarthria secondary to CP were compared to 20 age- and sex-matched typically developing children on 5 acoustic measures of connected speech. A logistic regression approach was used to derive an acoustic model that best predicted dysarthria status.

RESULTS

Results indicated that children with dysarthria secondary to CP differed from typically developing children on measures of multiple segmental and suprasegmental speech characteristics. An acoustic model containing articulation rate and the F2 range of diphthongs differentiated children with dysarthria from typically developing children with 87.5% accuracy.

CONCLUSION

This study serves as a first step toward developing an acoustic model that can be used to improve early identification of dysarthria in children with CP.

Sentence-Level Movements in Parkinson's Disease: Loud, Clear, and Slow Speech

PURPOSE

To further understand the effect of Parkinson's disease (PD) on articulatory movements in speech and to expand our knowledge of therapeutic treatment strategies, this study examined movements of the jaw, tongue blade, and tongue dorsum during sentence production with respect to speech intelligibility and compared the effect of varying speaking styles on these articulatory movements.

METHOD

Twenty-one speakers with PD and 20 healthy controls produced 3 sentences under normal, loud, clear, and slow speaking conditions. Speech intelligibility was rated for each speaker. A 3-dimensional electromagnetic articulograph tracked movements of the articulators. Measures included articulatory working spaces, ranges along the first principal component, average speeds, and sentence durations.

RESULTS

Speakers with PD demonstrated significantly smaller jaw movements as well as shorter than normal sentence durations. Between-speaker variation in movement size of the jaw, tongue blade, and tongue dorsum was associated with speech intelligibility. Analysis of speaking conditions revealed similar patterns of change in movement measures across groups and articulators: larger than normal movement sizes and faster speeds for loud speech, increased movement sizes for clear speech, and larger than normal movement sizes and slower speeds for slow speech.

CONCLUSIONS

Sentence-level measures of articulatory movements are sensitive to both disease-related changes in PD and speaking-style manipulations.

A Cross-Language Study of Acoustic Predictors of Speech Intelligibility in Individuals With Parkinson's Disease

PURPOSE

The present study aimed to compare acoustic models of speech intelligibility in individuals with the same disease (Parkinson's disease [PD]) and presumably similar underlying neuropathologies but with different native languages (American English [AE] and Korean).

METHOD

A total of 48 speakers from the 4 speaker groups (AE speakers with PD, Korean speakers with PD, healthy English speakers, and healthy Korean speakers) were asked to read a paragraph in their native languages. Four acoustic variables were analyzed: acoustic vowel space, voice onset time contrast scores, normalized pairwise variability index, and articulation rate. Speech intelligibility scores were obtained from scaled estimates of sentences extracted from the paragraph.

RESULTS

The findings indicated that the multiple regression models of speech intelligibility were different in Korean and AE, even with the same set of predictor variables and with speakers matched on speech intelligibility across languages. Analysis of the descriptive data for the acoustic variables showed the expected compression of the vowel space in speakers with PD in both languages, lower normalized pairwise variability index scores in Korean compared with AE, and no differences within or across language in articulation rate.

CONCLUSIONS

The results indicate that the basis of an intelligibility deficit in dysarthria is likely to depend on the native language of the speaker and listener. Additional research is required to explore other potential predictor variables, as well as additional language comparisons to pursue cross-linguistic considerations in classification and diagnosis of dysarthria types.

Range and Precision of Formant Movement in Pediatric Dysarthria

PURPOSE

This study aimed to improve understanding of speech characteristics associated with dysarthria in children with cerebral palsy by analyzing segmental and global formant measures in single-word and sentence contexts.

METHOD

Ten 5-year-old children with cerebral palsy and dysarthria and 10 age-matched, typically developing children participated in this study. Vowel space area and second formant interquartile range were measured from children's elicited productions of single words and sentences.

RESULTS

Results showed that the children with dysarthria had significantly smaller vowel space areas than typically developing children in both word and sentence contexts; however, overall ranges of second formant movement did not differ between groups in word or sentence contexts. Additional analysis of single words revealed that, compared to typical children, children with dysarthria had smaller second formant interquartile ranges in single words with phonetic contexts requiring large changes in vocal tract configuration, but not in single words with monophthongs.

CONCLUSIONS

Results of this study suggest that children with dysarthria may not have globally reduced ranges of articulatory movement compared to typically developing peers; however, they do exhibit reduced precision in producing phonetic targets.

Perceptual Anchors and the Dispersion of Nasality Ratings

Objective

This investigation studied the effects of perceptual anchors on the dispersion and reliability of listener ratings of nasality.

Design

Listeners (N = 129) were assigned to one of six listening groups. Each group rated nasality independently for 100 speech samples on a seven-point scale that ranged from 1 = normal nasality to 7 = severe hypernasality. The anchors used were examples of a 1, 3, 4, 5, and/or 7 on the rating scale. These anchors were played selectively to group 2 (4), group 3 (1 and 7), group 4 (3 and 5), group 5 (1, 4, 7), and group 6 (7). Group 1 had no anchor.

Participants

Of the speakers, 95 were children followed by a craniofacial team and five were children without histories of speech disorders.

Main Outcome Measures

The outcome measures were 12,900 ratings of nasality on a seven-point scale.

Results

Q values showed that group 5, which was the only group to receive three anchors, had the lowest, or best, Q value (0.78), and group 1 (no anchor) had the highest, or worst, Q value (0.99). Across groups, the most reliable ratings were those at scale values 1 (Q = 0.46) and 7 (Q = 0.56). The least reliable ratings were at scale values 3 (Q = 1.01), 4 (Q = 1.03), and 5 (Q = 1.06).

Conclusions

Nasality rating reliability/dispersion was influenced by the presence and location of anchor stimuli. Consistent with absolute judgment theory, nasality ratings showed a strong end effect.

Game-Based Augmented Visual Feedback for Enlarging Speech Movements in Parkinson's Disease

PURPOSE

The purpose of this pilot study was to demonstrate the effect of augmented visual feedback on acquisition and short-term retention of a relatively simple instruction to increase movement amplitude during speaking tasks in patients with dysarthria due to Parkinson's disease (PD).

METHOD

Nine patients diagnosed with PD, hypokinetic dysarthria, and impaired speech intelligibility participated in a training program aimed at increasing the size of their articulatory (tongue) movements during sentences. Two sessions were conducted: a baseline and training session, followed by a retention session 48 hr later. At baseline, sentences were produced at normal, loud, and clear speaking conditions. Game-based visual feedback regarding the size of the articulatory working space (AWS) was presented during training.

RESULTS

Eight of nine participants benefited from training, increasing their sentence AWS to a greater degree following feedback as compared with the baseline loud and clear conditions. The majority of participants were able to demonstrate the learned skill at the retention session.

CONCLUSIONS

This study demonstrated the feasibility of augmented visual feedback via articulatory kinematics for training movement enlargement in patients with hypokinesia due to PD.

SUPPLEMENTAL MATERIALS

https://doi.org/10.23641/asha.5116840.

Jaw Rotation in Dysarthria Measured With a Single Electromagnetic Articulography Sensor

PURPOSE

This study evaluated a novel method for characterizing jaw rotation using orientation data from a single electromagnetic articulography sensor. This method was optimized for clinical application, and a preliminary examination of clinical feasibility and value was undertaken.

METHOD

The computational adequacy of the single-sensor orientation method was evaluated through comparisons of jaw-rotation histories calculated from dual-sensor positional data for 16 typical talkers. The clinical feasibility and potential value of single-sensor jaw rotation were assessed through comparisons of 7 talkers with dysarthria and 19 typical talkers in connected speech.

RESULTS

The single-sensor orientation method allowed faster and safer participant preparation, required lower data-acquisition costs, and generated less high-frequency artifact than the dual-sensor positional approach. All talkers with dysarthria, regardless of severity, demonstrated jaw-rotation histories with more numerous changes in movement direction and reduced smoothness compared with typical talkers.

CONCLUSIONS

Results suggest that the single-sensor orientation method for calculating jaw rotation during speech is clinically feasible. Given the preliminary nature of this study and the small participant pool, the clinical value of such measures remains an open question. Further work must address the potential confound of reduced speaking rate on movement smoothness.

Acoustic variation during passage reading for speakers with dysarthria and healthy controls

PURPOSE

Acoustic variation in a passage read by speakers with dysarthria and healthy speakers was examined.

METHOD

15 speakers with Multiple Sclerosis (MS), 12 speakers with Parkinson's disease (PD), and 14 healthy speakers were studied. Acoustic variables included measures of global speech timing (e.g., articulation rate, pause characteristics), vocal intensity (e.g., mean sound pressure level and intensity modulation), and segmental articulation (i.e., utterance-level second formant interquartile range (F2 IQR)). Acoustic measures were obtained from three segments operationally defined to represent the beginning, middle, and end of a reading passage. Two speaking conditions associated with common treatment techniques for dysarthria were included for comparison to a habitual speaking condition. These conditions included a slower-than-habitual rate (Slow) and greater-than-habitual intensity (Loud).

RESULTS

There was some degree of acoustic variation across the three operationally-defined segments of the reading passage. The Slow, Loud and Habitual conditions yielded comparable characteristics of variation. Patterns of acoustic variation across the three passage segments also were largely similar across speaker groups.

CONCLUSIONS

Within-task acoustic variation during passage reading should be considered when making decisions regarding speech sampling in clinical practice and research. The contributions of speech disorder severity and linguistic variables to within-task acoustic change warrant further investigation.

LEARNING OUTCOMES

Readers will be able to (1) discuss the motivation for studying and understanding within-task variation in contextual speech, (2) describe patterns of acoustic variation for speakers with dysarthria and healthy speakers during passage reading, (3) discuss the relationship between non-habitual speaking conditions and within-task variation, (4) understand the need to consider within-speaker, within-task variation in speech sampling.

Comparison of Intelligibility Measures for Adults With Parkinson's Disease, Adults With Multiple Sclerosis, and Healthy Controls

PURPOSE

This study obtained judgments of sentence intelligibility using orthographic transcription for comparison with previously reported intelligibility judgments obtained using a visual analog scale (VAS) for individuals with Parkinson's disease and multiple sclerosis and healthy controls (K. Tjaden, J. E. Sussman, & G. E. Wilding, 2014).

METHOD

Speakers read Harvard sentences in habitual, clear, loud, and slow conditions. Sentence stimuli were equated for peak intensity and mixed with multitalker babble. A total of 50 listeners orthographically transcribed sentences. Procedures were identical to those for a VAS reported in Tjaden, Sussman, and Wilding (2014).

RESULTS

The percent correct scores from transcription were significantly higher in magnitude than the VAS scores. Multivariate linear modeling indicated that the pattern of findings for transcription and VAS was virtually the same with respect to differences among groups and speaking conditions. Correlation analyses further indicated a moderately strong, positive relationship between the two metrics. The majority of these correlations were significant. Last, intrajudge and interjudge listener reliability metrics for the two intelligibility tasks were comparable.

CONCLUSION

Results suggest that there may be instances when the less time-consuming VAS task may be a viable substitute for an orthographic transcription task when documenting intelligibility in mild dysarthria.

Variability and Diagnostic Accuracy of Speech Intelligibility Scores in Children

PURPOSE

We examined variability of speech intelligibility scores and how well intelligibility scores predicted group membership among 5-year-old children with speech motor impairment (SMI) secondary to cerebral palsy and an age-matched group of typically developing (TD) children.

METHOD

Speech samples varying in length from 1-4 words were elicited from 24 children with cerebral palsy (mean age 60.50 months) and 20 TD children (mean age 60.33 months). Two hundred twenty adult listeners made orthographic transcriptions of speech samples (n = 5 per child).

RESULTS

Variability associated with listeners made a significant contribution to explaining the variance in intelligibility scores for TD and SMI children, but the magnitude was greater for TD children. Intelligibility scores differentiated very well between children who have SMI and TD children when intelligibility was at or below approximately 75% and above approximately 85%.

CONCLUSIONS

Intelligibility seems to be a useful clinical tool for differentiating between TD children and children with SMI at 5 years of age; however, there is considerable variability within and between listeners, highlighting the need for more than one listener per child to ensure validity of an intelligibility measure.

Relationship between acoustic measures and speech naturalness ratings in Parkinson's disease: A within-speaker approach

This study investigated the acoustic basis of across-utterance, within-speaker variation in speech naturalness for four speakers with dysarthria secondary to Parkinson's disease (PD). Speakers read sentences and produced spontaneous speech. Acoustic measures of fundamental frequency, phrase-final syllable lengthening, intensity and speech rate were obtained. A group of listeners judged speech naturalness using a nine-point Likert scale. Relationships between judgements of speech naturalness and acoustic measures were determined for individual speakers with PD. Relationships among acoustic measures also were quantified. Despite variability between speakers, measures of mean F0, intensity range, articulation rate, average syllable duration, duration of final syllables, vocalic nucleus length of final unstressed syllables and pitch accent of final syllables emerged as possible acoustic variables contributing to within-speaker variations in speech naturalness. Results suggest that acoustic measures correlate with speech naturalness, but in dysarthric speech they depend on the speaker due to the within-speaker variation in speech impairment.

Acoustic and perceptual correlates of faster-than-habitual speech produced by speakers with Parkinson's disease and multiple sclerosis

Acoustic-perceptual characteristics of a faster-than-habitual rate (Fast condition) were examined for speakers with Parkinson's disease (PD) and multiple sclerosis (MS). Judgments of intelligibility for sentences produced at a habitual rate (Habitual condition) and at a faster-than-habitual rate (Fast condition) by 46 speakers with PD or MS as well as a group of 32 healthy speakers revealed that the Fast condition was, on average, associated with decreased intelligibility. However, some speakers' intelligibility did not decline. To further understand the acoustic characteristics of varied intelligibility in the Fast condition for speakers with dysarthria, a subgroup of speakers with PD or MS whose intelligibility did not decline in the Fast condition (no decline group, n=8) and a subgroup of speakers with significantly declined intelligibility (decline group, n=8) were compared. Acoustic measures of global speech timing, suprasegmental characteristics, and utterance-level segmental characteristics for vocalics were examined for the two subgroups. Results suggest acoustic contributions to intelligibility under rate modulation are complex. Potential clinical relevance and implications for the acoustic bases of intelligibility are discussed.

LEARNING OUTCOMES

Readers will be able to (1) discuss existing evidence for the use of rate change to facilitate intelligibility, (2) describe acoustic-perceptual characteristics of a faster-than-habitual rate among speakers with mild dysarthria, (3) discuss the relationships between rate, intelligibility, suprasegmental variables, and segmental variables, (4) identify the need to further investigate the acoustic basis for intelligibility and its potential theoretical and clinical implications.

Relationship between acoustic measures and judgments of intelligibility in Parkinson's disease: a within-speaker approach

This study investigated the acoustic basis of within-speaker, across-utterance variation in sentence intelligibility for 12 speakers with dysarthria secondary to Parkinson's disease (PD). Acoustic measures were also obtained for 12 healthy controls for comparison to speakers with PD. Speakers read sentences using their typical speech style. Acoustic measures of speech rate, articulatory rate, fundamental frequency, sound pressure level and F2 interquartile range (F2 IQR) were obtained. A group of listeners judged sentence intelligibility using a computerized visual-analog scale. Relationships between judgments of intelligibility and acoustic measures were determined for individual speakers with PD. Relationships among acoustic measures were also quantified. Although considerable variability was noted, articulatory rate, fundamental frequency and F2 IQR were most frequently associated with within-speaker variation in sentence intelligibility. Results suggest that diversity among speakers with PD should be considered when interpreting results from group analyses.

Hybridizing conversational and clear speech to investigate the source of increased intelligibility in speakers with Parkinson's disease

PURPOSE

A speech analysis-resynthesis paradigm was used to investigate segmental and suprasegmental acoustic variables explaining intelligibility variation for 2 speakers with Parkinson's disease (PD).

METHOD

Sentences were read in conversational and clear styles. Acoustic characteristics from clear sentences were extracted and applied to conversational sentences, yielding 6 hybridized versions of sentences in which segment durations, short-term spectrum, energy characteristics, or fundamental frequency characteristics for clear productions were applied individually or in combination to conversational productions. Listeners (N = 20) judged intelligibility in transcription and scaling tasks.

RESULTS

Intelligibility increases above conversation were more robust for transcription, but the pattern of intelligibility improvement was similar across tasks. For 1 speaker, hybridization involving only clear energy characteristics yielded an 8.7% improvement in transcription intelligibility above conversation. For the other speaker, hybridization involving clear spectrum yielded an 18% intelligibility improvement, whereas hybridization involving both clear spectrum and duration yielded a 13.4% improvement.

CONCLUSIONS

Not all production changes accompanying clear speech explain its improved intelligibility. Suprasegmental adjustments contributed to intelligibility improvements when segmental adjustments, as inferred from vowel space area, were not robust. Hybridization can be used to identify acoustic variables explaining intelligibility variation in mild dysarthria secondary to PD.

Impact of clear, loud, and slow speech on scaled intelligibility and speech severity in Parkinson's disease and multiple sclerosis

PURPOSE

The perceptual consequences of rate reduction, increased vocal intensity, and clear speech were studied in speakers with multiple sclerosis (MS), Parkinson's disease (PD), and healthy controls.

METHOD

Seventy-eight speakers read sentences in habitual, clear, loud, and slow conditions. Sentences were equated for peak amplitude and mixed with multitalker babble for presentation to listeners. Using a computerized visual analog scale, listeners judged intelligibility or speech severity as operationally defined in Sussman and Tjaden (2012).

RESULTS

Loud and clear but not slow conditions improved intelligibility relative to the habitual condition. With the exception of the loud condition for the PD group, speech severity did not improve above habitual and was reduced relative to habitual in some instances. Intelligibility and speech severity were strongly related, but relationships for disordered speakers were weaker in clear and slow conditions versus habitual.

CONCLUSIONS

Both clear and loud speech show promise for improving intelligibility and maintaining or improving speech severity in multitalker babble for speakers with mild dysarthria secondary to MS or PD, at least as these perceptual constructs were defined and measured in this study. Although scaled intelligibility and speech severity overlap, the metrics further appear to have some separate value in documenting treatment-related speech changes.

Acoustic and perceptual consequences of clear and loud speech

OBJECTIVE

Several issues concerning F2 slope in dysarthria were addressed by obtaining speech acoustic measures and judgments of intelligibility for sentences produced in Habitual, Clear and Loud conditions by speakers with Parkinson's disease (PD) and healthy controls.

PATIENTS AND METHODS

Acoustic measures of average and maximum F2 slope for diphthongs, duration and intensity were obtained. Listeners judged intelligibility using a visual analog scale. Differences in measures among groups and conditions as well as relationships among measures were examined.

RESULTS

Average and maximum F2 slope metrics were strongly correlated, but only average F2 slope consistently differed among groups and conditions, with shallower slopes for the PD group and steeper slopes for Clear speech versus Habitual and Loud. Clear and Loud speech were also characterized by lengthened durations, increased intensity and improved intelligibility versus Habitual. F2 slope and intensity were unrelated, and F2 slope was a significant predictor of intelligibility.

CONCLUSION

Average diphthong F2 slope was more sensitive than maximum F2 slope to articulatory mechanism involvement in mild dysarthria in PD. F2 slope holds promise as an objective measure of treatment-related changes in the articulatory mechanism for therapeutic techniques that focus on articulation.

Acoustic-perceptual relationships in variants of clear speech

OBJECTIVE

The acoustic basis of intelligibility associated with varied clear speech instructions was studied.

METHODS

Twelve healthy speakers read 18 sentences in 'habitual', 'clear', 'hearing impaired' and 'overenunciate' conditions. The latter 3 conditions are varieties of clear speech. Acoustic measures included tense and lax vowel space area, a measure of vowel spectral change, articulation rate and sentence-level vocal intensity. Sentences were mixed with multitalker babble to prevent ceiling effects and were orthographically transcribed by 40 listeners. Percent-correct scores were obtained for each speaker and condition. Regression analyses were used to quantify relationships between acoustic measures and intelligibility.

RESULTS

Univariate regressions indicated that greater magnitudes of acoustic change in nonhabitual conditions were associated with greater increases in intelligibility. Multivariate regression analysis further indicated that lax vowel space, articulation rate and vocal intensity were significant predictors of intelligibility.

CONCLUSIONS

Acoustic variables associated with intelligibility differed depending on whether relationships were examined using univariate or multivariate statistics. Multivariate statistics indicated that articulation rate was the strongest predictor of improvements in intelligibility above and beyond all other variables studied. The findings have implications for optimizing therapeutic use of clear speech for clinical populations.

Accuracy of perceptual and acoustic methods for the detection of inspiratory loci in spontaneous speech

The present study investigates the accuracy of perceptually and acoustically determined inspiratory loci in spontaneous speech for the purpose of identifying breath groups. Sixteen participants were asked to talk about simple topics in daily life at a comfortable speaking rate and loudness while connected to a pneumotach and audio microphone. The locations of inspiratory loci were determined on the basis of the aerodynamic signal, which served as a reference for loci identified perceptually and acoustically. Signal detection theory was used to evaluate the accuracy of the methods. The results showed that the greatest accuracy in pause detection was achieved (1) perceptually, on the basis of agreement between at least two of three judges, and (2) acoustically, using a pause duration threshold of 300 ms. In general, the perceptually based method was more accurate than was the acoustically based method. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci for spontaneous speech should be weighed in selecting a method of breath group determination.

Spatiotemporal coupling of the tongue in amyotrophic lateral sclerosis

PURPOSE

The primary aim of the investigation was to identify deficits in spatiotemporal coupling between tongue regions in amyotrophic lateral sclerosis (ALS). The relations between disease-related changes in tongue movement patterns and speech intelligibility were also determined. Methods The authors recorded word productions from 11 individuals with ALS with mild, moderate, and severe dysarthria using an x-ray microbeam during word productions. A coupling index based on sliding window covariance was used to determine disease-related changes in the coupling between the tongue regions across each word.

RESULTS

The results indicated decreased spatiotemporal coupling of mid-posterior tongue regions and reduced tongue speed in the ALS-moderate subgroup. Changes in the range of tongue coupling relations and speed of movement were highly correlated with speech intelligibility.

CONCLUSIONS

These results provide new insights into the loss of lingual motor control due to ALS and suggest that measures of tongue performance may provide useful indicators of bulbar disease severity and progression.

Perceptual measures of speech from individuals with Parkinson's disease and multiple sclerosis: intelligibility and beyond

PURPOSE

The primary purpose of this study was to compare percent correct word and sentence intelligibility scores for individuals with multiple sclerosis (MS) and Parkinson's disease (PD) with scaled estimates of speech severity obtained for a reading passage.

METHOD

Speech samples for 78 talkers were judged, including 30 speakers with MS, 16 speakers with PD, and 32 healthy control speakers. Fifty-two naive listeners performed forced-choice word identification, sentence transcription, or visual analog scaling of speech severity for the Grandfather Passage (Duffy, 2005). Three expert listeners also scaled speech severity for the Grandfather Passage.

RESULTS

Percent correct word and sentence intelligibility scores did not cleanly differentiate speakers with MS, PD, or control speakers. In contrast, both naive and expert listener groups judged reading passages produced by speakers with MS and PD to be more severely impaired than reading passages produced by control talkers.

CONCLUSION

Scaled estimates of speech severity appear to be sensitive to aspects of speech impairment in MS and PD not captured by word or sentence intelligibility scores. One implication is that scaled estimates of speech severity might prove useful for documenting speech changes related to disease progression or even treatment for individuals with MS and PD with minimal reduction in intelligibility.

Speech and pause characteristics associated with voluntary rate reduction in Parkinson's disease and Multiple Sclerosis

The primary purpose of this study was to investigate how speakers with Parkinson's disease (PD) and Multiple Sclerosis (MS) accomplish voluntary reductions in speech rate. A group of talkers with no history of neurological disease was included for comparison. This study was motivated by the idea that knowledge of how speakers with dysarthria voluntarily accomplish a reduced speech rate would contribute toward a descriptive model of speaking rate change in dysarthria. Such a model has the potential to assist in identifying rate control strategies to receive focus in clinical treatment programs and also would advance understanding of global speech timing in dysarthria. All speakers read a passage in Habitual and Slow conditions. Speech rate, articulation rate, pause duration, and pause frequency were measured. All speaker groups adjusted articulation time as well as pause time to reduce overall speech rate. Group differences in how voluntary rate reduction was accomplished were primarily one of quantity or degree. Overall, a slower-than-normal rate was associated with a reduced articulation rate, shorter speech runs that included fewer syllables, and longer more frequent pauses. Taken together, these results suggest that existing skills or strategies used by patients should be emphasized in dysarthria training programs focusing on rate reduction. Results further suggest that a model of voluntary speech rate reduction based on neurologically normal speech shows promise as being applicable for mild to moderate dysarthria.

LEARNING OUTCOMES

The reader will be able to: (1) describe the importance of studying voluntary adjustments in speech rate in dysarthria, (2) discuss how speakers with Parkinson's disease and Multiple Sclerosis adjust articulation time and pause time to slow speech rate.

Effects of speaking task on intelligibility in Parkinson's disease

Intelligibility tests for dysarthria typically provide an estimate of overall severity for speech materials elicited through imitation or read from a printed script. The extent to which these types of tasks and procedures reflect intelligibility for extemporaneous speech is not well understood. The purpose of this study was to compare intelligibility estimates obtained for a reading passage and an extemporaneous monologue produced by 12 speakers with Parkinson's disease (PD). The relationship between structural characteristics of utterances and scaled intelligibility was explored within speakers. Speakers were audio-recorded while reading a paragraph and producing a monologue. Speech samples were separated into individual utterances for presentation to 70 listeners who judged intelligibility using orthographic transcription and direct magnitude estimation (DME). Results suggest that scaled estimates of intelligibility for reading show potential for indexing intelligibility of an extemporaneous monologue. Within-speaker variation in scaled intelligibility also was related to the number of words per speech run for extemporaneous speech.

Accuracy of perceptually based and acoustically based inspiratory loci in reading

Investigations of speech often involve the identification of inspiratory loci in continuous recordings of speech. The present study investigates the accuracy of perceptually determined and acoustically determined inspiratory loci. While wearing a circumferentially vented mask connected to a pneumotach, 16 participants read two passages. The perceptually determined and acoustically determined inspiratory loci were compared with the actual loci of inspiration, which were determined aerodynamically. The results showed that (1) agreement across all three judges was the most accurate of the approaches considered here for detecting inspiratory loci based on listening; (2) the most accurate pause duration threshold for detecting inspiratory loci was 250 msec; and (3) the perceptually based breath-group determination was more accurate than the acoustically based determination of pause duration. Inconsistencies among perceptually determined, acoustically determined, and aerodynamically determined inspiratory loci are not negligible and, therefore, need to be considered when researchers design experiments on breath groups in speech.

Formant centralization ratio: a proposal for a new acoustic measure of dysarthric speech

PURPOSE

The vowel space area (VSA) has been used as an acoustic metric of dysarthric speech, but with varying degrees of success. In this study, the authors aimed to test an alternative metric to the VSA-the formant centralization ratio (FCR), which is hypothesized to more effectively differentiate dysarthric from healthy speech and register treatment effects.

METHOD

Speech recordings of 38 individuals with idiopathic Parkinson's disease and dysarthria (19 of whom received 1 month of intensive speech therapy [Lee Silverman Voice Treatment; LSVT LOUD]) and 14 healthy control participants were acoustically analyzed. Vowels were extracted from short phrases. The same vowel-formant elements were used to construct the FCR, expressed as (F2u + F2a + F1i + F1u) / (F2i + F1a), the VSA, expressed as ABS([F1i x (F2a - F2u) + F1a x (F2u - F2i) + F1u x (F2i - F2a)] / 2), a logarithmically scaled version of the VSA (LnVSA), and the F2i /F2u ratio.

RESULTS

Unlike the VSA and the LnVSA, the FCR and F2i/F2u ratio robustly differentiated dysarthric from healthy speech and were not gender sensitive. All metrics effectively registered treatment effects and were strongly correlated with each other.

CONCLUSION

Albeit preliminary, the present findings indicate that the FCR is a sensitive, valid, and reliable acoustic metric for distinguishing dysarthric from unimpaired speech and for monitoring treatment effects, probably because of reduced sensitivity to interspeaker variability and enhanced sensitivity to vowel centralization.

Direct magnitude estimation of articulation rate in boys with fragile X syndrome

PURPOSE

To compare the perceived articulation rate of boys with fragile X syndrome (FXS) with that of chronologically age-matched (CA) boys and to determine segmental and/or prosodic factors that account for perceived rate.

METHOD

Ten listeners used direct magnitude estimation procedures to judge the articulation rates of 7 boys with FXS only, 5 boys with FXS and a diagnosis of autism spectrum disorder (ASD), and 12 CA boys during sentence repetition. Sentences had similar articulation rates in syllables per second as determined acoustically. Four segmental/prosodic factors were used to predict perceived rate: (a) percentage consonants correct, (b) overall fundamental frequency (F(0)) level, (c) sentence-final F(0) drop, and (d) acoustically determined articulation rate with the final word of the sentence excluded.

RESULTS

Boys with FXS and ASD were judged to talk faster than CA controls. Multiple linear regression indicated that articulation rate with the final word of the sentence excluded and sentence-final F(0) drop accounted for 91% of the variance for perceived rate.

CONCLUSIONS

Descriptions of speakers with FXS as having fast and/or fluctuating articulation rates may be influenced by autism status. Also, atypical sentence-final prosody may be related to perceived rate in boys with FXS and ASD.

Telediagnostic assessment of intelligibility in dysarthria: a pilot investigation of MVP-online

BACKGROUND

A most important index of functional impairment in dysarthria is intelligibility. The Munich Intelligibility Profile (MVP) is a computer-based method for the assessment of the intelligibility of dysarthric patients. A multi-user online version of MVP is now available.

AIMS

To describe the structure of MVP-online and to evaluate important psychometric features of the test.

METHODS

MVP-online was used in 200 test administrations (48 normal, 152 dysarthric). Intelligibility scores were based on 884 listening sessions (30 listeners). Various measures of listener agreement and of internal consistency were examined.

RESULTS

Normal speakers achieved scores between 95% and 100% intelligible, the range for dysarthric patients was 20-100%. Test reliability turned out to be good when scores from 2 to 3 listeners were averaged. The amounts of long-term listener learning and of within-test listener adaptation were low. MVP-online proved to have a high internal consistency.

CONCLUSIONS

MVP-online is an efficient, reliable and valid method for the assessment of intelligibility in dysarthria. It is useful for clinical standard diagnosis, for large-scale studies of speech motor impairment, and for longitudinal studies, e.g. in treatment research.

LEARNING OUTCOMES

The reader will be able to (1) understand the requirements to be met by clinical methods of intelligibility testing in the assessment of dysarthria, (2) evaluate the design of a new, computer-based rhyme test, (3) estimate the value of a tele-diagnostic approach in diagnosis, and (4) discuss the psychometric properties of intelligibility testing methods.

Articulatory movements during vowels in speakers with dysarthria and healthy controls

PURPOSE

This study compared movement characteristics of markers attached to the jaw, lower lip, tongue blade, and dorsum during production of selected English vowels by normal speakers and speakers with dysarthria due to amyotrophic lateral sclerosis (ALS) or Parkinson disease (PD). The study asked the following questions: (a) Are movement measures different for healthy controls and speakers with ALS or PD, and (b) Are articulatory profiles comparable for speakers with ALS and speakers with PD?

METHOD

Nineteen healthy controls and 15 speakers with dysarthria participated in this study. The severity of dysarthria varied across individuals and between the 2 disorder groups. The stimuli were 10 words (i.e., seed, feed, big, dish, too, shoo, bad, cat, box, and dog) embedded into sentences read at a comfortable reading rate. Movement data were collected using the X-ray microbeam. Movement measures included distances, durations, and average speeds of vowel-related movement strokes.

RESULTS

Differences were found (a) between speakers with ALS and healthy controls and (b) between speakers with ALS and PD, particularly in movement speed. Tongue movements in PD and ALS were more consistently different from healthy controls than jaw and lower lip movements. This study showed that the effects of neurologic disease on vowel production are often articulator-, vowel-, and context-specific.

CONCLUSIONS

Differences in severity between the speakers with PD and ALS may have accounted for some of the differences in movement characteristics between the groups. These factors need to be carefully considered when describing the nature of speech disorder and developing empirically based evaluation and treatment strategies for dysarthria.

Speech and Swallowing in Parkinson's Disease

Dysarthria and dysphagia occur frequently in Parkinson's disease (PD). Reduced speech intelligibility is a significant functional limitation of dysarthria, and in the case of PD is likely related articulatory and phonatory impairment. Prosodically-based treatments show the most promise for addressing these deficits as well as for maximizing speech intelligibility. Communication-oriented strategies also may help to enhance mutual understanding between a speaker and listener. Dysphagia in PD can result in serious health issues, including aspiration pneumonia, malnutrition, and dehydration. Early identification of swallowing abnormalities is critical so as to minimize the impact of dysphagia on health status and quality of life. Feeding modifications, compensatory strategies, and therapeutic swallowing techniques all have a role in the management of dysphagia in PD.