Control Speakers Research Articles

Speech rate and fluency in young-onset Parkinson’s disease: A longitudinal case study from early to post brain surgery stage

ABSTRACT The aim of this study is to analyse the speech rate, pausing and fluency of a patient with young-onset Parkinson’s Disease in different stages of the disease. Speech samples of the patient were recorded in the early stages of the disease until after the brain surgery. The recordings were compared to the speech of healthy control speakers. Speech rate, articulation rate, pausing and the frequency of disfluencies were analysed. Results show that all parameters are influenced by the severity of the disease, but articulation rate is the most affected.

Duct quiet zones utilization for an enhancement the acoustical air-condition noise control

<p class="TableParagraph">This paper investigates the duct’s noise distribution pattern due to the heating, ventilation, and air conditioning systems. This study is considering the longitudinal sound wave distribution that can permit a higher reduction of these heating, ventilation, and air conditioning systems duct noise. The proposed technique is depending on the lowest sound pressure level points in the duct or duct quiet zones. Moreover, each heating, ventilation, and air conditioning systems duct has several quiet zones, depending on the sound pressure level of the fan noise source and the duct length as well as the duct diameter. Furthermore, the noise standing wave has a wavelength (λ) which is the distance between two successive quiet zones. This work utilizes orthogonal acoustical noise with the standing wave via feed-forward control speakers. This system confirmed that the distance (λ) is linearly proportional to the duct source noise level. This system noise reduction enhancement has been fulfilled by installing further noise feed-forward control speakers at different duct quiet zones. The system simulation results were displaying satisfactory agreement with the field experimental results.</p>

Plasticity of Native Intonation in the L1 of English Migrants to Austria

This study examines the plasticity of native language intonation in English-Austrian German sequential bilinguals who have migrated to Austria in adulthood by comparing it to that of monolingual English and monolingual Austrian control speakers. Intonation was analysed along four intonation dimensions proposed by the L2 Intonation Learning theory (LILt): the inventory of categorical phonological elements (‘systemic’ dimension), their phonetic implementation (‘realizational’), the meaning associated with phonological elements (‘semantic’), and their frequency of use (‘frequency’). This allowed us to test whether each intonation dimension is equally permeable to L2-on-L1 influences. The results revealed L2-on-L1 effects on each dimension. These consistently took the form of assimilation. The extent of assimilation appeared to depend on whether the cross-language differences were gradient or categorical, with the former predominantly resulting in intermediate merging and the latter in a complete transfer. The results suggest that native intonation remains plastic in all its dimensions, resulting in pervasive modifications towards the L2. Finally, in this first application of the LILt to the context of L1 attrition, the study confirms the model’s suitability not only to acquisition of L2 intonation but also for predicting where modifications of L1 intonation are likely to occur.

A cross-linguistic perspective to classification of healthiness of speech in Parkinson's disease

People with Parkinson's disease often experience communication problems. The current cross-linguistic study investigates how listeners' perceptual judgements of speech healthiness are related to the acoustic changes appearing in the speech of people with Parkinson's disease. Accordingly, we report on an online experiment targeting perceived healthiness of speech. We studied the relations between healthiness perceptual judgements and a set of acoustic characteristics of speech in a cross-sectional design. We recruited 169 participants, who performed a classification task judging speech recordings of Dutch speakers with Parkinson's disease and of Dutch control speakers as ‘healthy’ or ‘unhealthy’. The groups of listeners differed in their training and expertise in speech language therapy as well as in their native languages. Such group separation allowed us to investigate the acoustic correlates of speech healthiness without influence of the content of the recordings. We used a Random Forest method to predict listeners' responses. Our findings demonstrate that, independently of expertise and language background, when classifying speech as healthy or unhealthy listeners are more sensitive to speech rate, presence of phonation deficiency reflected by maximum phonation time measurement, and centralization of the vowels. The results indicate that both specifics of the expertise and language background may lead to listeners relying more on the features from either prosody or phonation domains. Our findings demonstrate that more global perceptual judgements of different listeners classifying speech of people with Parkinson's disease may be predicted with sufficient reliability from conventional acoustic features. This suggests universality of acoustic change in speech of people with Parkinson's disease. Therefore, we concluded that certain aspects of phonation and prosody serve as prominent markers of speech healthiness for listeners independent of their first language or expertise. Our findings have outcomes for the clinical practice and real-life implications for subjective perception of speech of people with Parkinson's disease, while information about particular acoustic changes that trigger listeners to classify speech as ‘unhealthy’ can provide specific therapeutic targets in addition to the existing dysarthria treatment in people with Parkinson's disease. • Acoustic features predict the perceptual judgements of speech healthiness. • Phonation and prosody are the best predictors of speech healthiness judgements. • Listeners' language background influences the importance of acoustic predictors. • Expertise and language background have little influence on prediction accuracy.

Intelligibility of pseudo-whispered speech after total laryngectomy

ABSTRACT This study aimed to assess the intelligibility of so-called ‘pseudo-whispered speech’ (pseudo-WS), as produced without voice nor pulmonic airstream by some alaryngeal patients prior to rehabilitation. Several perception tests were submitted to three experienced clinicians and three naive listeners, relying on the speech samples of 20 French native speakers: 10 alaryngeal speakers, solely using pseudo-WS when starting speech therapy up to six months after total laryngectomy, and 10 control speakers, recorded in the closest speech mode available, whispered speech (WS). Experts were asked to identify consonants (C) in the /a/+C+/a/ context and to rate intelligibility, unintended additive noise, and fluency on a likert-scale, while naive listeners completed a quantitative test of intelligibility. Intelligibility of WS was found to be high, with scores ranging from 46.33/54 to 53.67/54 (median 52.5, interquartile range 2.33) for the quantitative test, and segmental intelligibility ranging from 68.75% to 94.79% (median 87.5, interquartile range 17.71). Segmental confusion affected voicing in favour of unvoiced consonants, as previously reported in the literature. By contrast, intelligibility of pseudo-WS was found to be poor, with scores ranging from 1/54 (unintelligibility) to 28.33/54 (median 8.66, interquartile range 14.67) for the quantitative test, and segmental intelligibility ranging from 3.13% to 28.13% (median 9.24, interquartile range 14.58). Segmental intelligibility was not uniformly affected: stops, labials and unvoiced consonants were better identified than other categories. Finally, a significant correlation was found between global intelligibility and articulatory precision, while unintended additive noise and fluency seemed to play no role.

Prosodic features in Finnish-speaking adults with Parkinson´s disease

ABSTRACT The aim of this study was to assess prosodic features in Finnish speakers with (n = 16) and without (n = 20) Parkinson’s disease (PD), as there are no published studies to date of prosodic features in Finnish speakers with PD. Chosen metrics were articulation rate (syllables/second), pitch (mean F0) and pitch variability (standard deviation F0), energy proportion below 1 kHz (epb1kHz), normalised pairwise variability index (nPVI), and a novel syllabic prosody index (SPI). Four statistically significant results were found: (1) energy was distributed more to lower frequencies in speakers with PD compared to control speakers, (2) male PD speakers had higher pitch and (3) higher syllabic prosody index compared to control males, and (4) female PD speakers had narrower pitch variability than controls. In this study, PD was manifested as less emphatic and breathier voice. Interestingly, male PD speakers’ dysprosody was manifested as an effortful speaking style, whereas female PD speakers exhibited dysprosody with a monotonous speaking style. A novel syllable-based prosody index could be a potentially useful tool in analysing prosody in disordered speech.

Validity of Off-the-Shelf Automatic Speech Recognition for Assessing Speech Intelligibility and Speech Severity in Speakers With Amyotrophic Lateral Sclerosis.

There is increasing interest in using automatic speech recognition (ASR) systems to evaluate impairment severity or speech intelligibility in speakers with dysarthria. We assessed the clinical validity of one currently available off-the-shelf (OTS) ASR system (i.e., a Google Cloud ASR API) for indexing sentence-level speech intelligibility and impairment severity in individuals with amyotrophic lateral sclerosis (ALS), and we provided guidance for potential users of such systems in research and clinic. Using speech samples collected from 52 individuals with ALS and 20 healthy control speakers, we compared word recognition rate (WRR) from the commercially available Google Cloud ASR API (Machine WRR) to clinician-provided judgments of impairment severity, as well as sentence intelligibility (Human WRR). We assessed the internal reliability of Machine and Human WRR by comparing the standard deviation of WRR across sentences to the minimally detectable change (MDC), a clinical benchmark that indicates whether results are within measurement error. We also evaluated Machine and Human WRR diagnostic accuracy for classifying speakers into clinically established categories. Human WRR achieved better accuracy than Machine WRR when indexing speech severity, and, although related, Human and Machine WRR were not strongly correlated. When the speech signal was mixed with noise (noise-augmented ASR) to reduce a ceiling effect, Machine WRR performance improved. Internal reliability metrics were worse for Machine than Human WRR, particularly for typical and mildly impaired severity groups, although sentence length significantly impacted both Machine and Human WRRs. Results indicated that the OTS ASR system was inadequate for early detection of speech impairment and grading overall speech severity. While Machine and Human WRR were correlated, ASR should not be used as a one-to-one proxy for transcription speech intelligibility or clinician severity ratings. Overall, findings suggested that the tested OTS ASR system, Google Cloud ASR, has limited utility for grading clinical speech impairment in speakers with ALS.

Effects of delay, length, and frequency on onset RTs and word durations: Articulatory planning uses flexible units but cannot be prepared

ABSTRACT There is debate regarding whether most articulatory planning occurs offline (rather than online) and whether the products of off-line processing are stored in a separate articulatory buffer until a large enough chunk is ready for production. This hypothesis predicts that delayed naming conditions should reduce not only onset RTs but also word durations because articulatory plans will be buffered and kept ready. We have tested this hypothesis with young control speakers, an aphasic speaker , and an age and education-matched speaker, using repetition, reading and picture-naming tasks. Contrary to the off-line hypothesis, delayed conditions strongly reduced onset RTs, but had no benefit for word durations. In fact, we found small effects in the opposite direction. Moreover, frequency and imageability affected word durations even in delayed conditions, consistent with articulatory processing continuing on-line. The same pattern of results was found in CS and in control participants, strengthening confidence in our results. There is debate regarding whether most articulatory planning occurs offline (rather than online) and whether the results of off-line processing are stored in a separate articulatory buffer until a large enough chunk is ready for production. This hypothesis predicts that delayed naming conditions should reduce not only onset RTs but also word durations because articulatory plans will be buffered and kept ready. We have tested young control speakers, an aphasic speaker, and an age and education matched speaker, using repetition, reading and picture naming tasks. Contrary to the off-line hypothesis, delayed conditions strongly reduced onset RTs, but had no benefit for word durations. In fact, we found small effects in the opposite direction. Moreover, frequency and imageability affected word durations even in delayed conditions, consistent with articulatory processing continuing on-line. The same pattern of results was found in CS and in control participants, strengthening confidence in our results.

Minimally Detectable Change of Speech Intelligibility in Speakers With Multiple Sclerosis and Parkinson's Disease.

This study sought to determine the minimally detectable change (MDC) of sentence intelligibility for speakers with multiple sclerosis (MS) and Parkinson's disease (PD). Speakers included 78 participants consisting of 32 neurologically healthy control speakers, 30 speakers with MS, and 16 speakers with PD. All speakers were recorded reading 11 sentences comprising the Speech Intelligibility Test (SIT), which were subsequently transcribed by inexperienced listeners. Percent correct scores were calculated for each sentence. An average percent correct score was also calculated for each speaker. The MDC at the 95% confidence interval was calculated using the following formula: MDC95 = 1.96 × √2 × standard error of measurement. Speakers were divided into operationally defined categories of severity, and MDCs were calculated for each category to permit comparison to MDCs reported for speakers with amyotrophic lateral sclerosis (ALS). Kruskal-Wallis tests were conducted to compare MDCs between groups and severity categories. The average MDC95 for control speakers was 5.53% (range = 3.21%-7.47%) and was statistically smaller than MDCs for speakers with MS (average = 10.08%, range = 5.30%-15.62%) and those for speakers with PD (average = 10.98%, range = 8.60%-13.98%). Statistical analyses further revealed significant differences between MDCs across severity categories. In agreement with previous work in ALS conducted under similar conditions (i.e., orthographic transcription of SIT sentences in a quiet listening environment), the MDC95 of speech intelligibility ranged from 3% to 10% for speakers with MS and PD who have mildly impaired speech. These estimates are a step toward the development of a universal language with which to evaluate speech changes in a variety of patient populations.

Is there a continuum between speech and other oromotor tasks? evidence from motor speech disorders

ABSTRACT Background Oral diadochokinetic (DDK) tasks are widely used in the assessment of patients with motor speech disorders (MSD). They require the repetition of homogeneous and of heterogeneous syllables at a maximum rate. The nature of DDK tasks is a matter of debate: although they are usually considered as “non-speech”, given the involvement of real speech syllables, they have also been recognized to share more properties and requirements with speech as compared to other oromotor behaviours (i.e., non-speech gestures). Additionally, the production of heterogeneous syllables has been suggested to exhibit closer correspondence with speech given the production of a cluster of different syllables, as compared to the repetition of a monosyllable. Each DDK task being differently related to speech supports the assumption of a continuum between speech and other oromotor processes, in which tasks with increasingly speech-like properties may overlap to a larger extent with speech. Aim To test the potentially differential relationship between speech and DDK tasks in patients with MSD. Traditional views of MSD claim that speech and other oromotor behaviours are impaired in patients with dysarthria, while patients with AoS present with speech being exclusively compromised. This suggests that DDK tasks should be differently affected in these two MSD populations. Moreover, in the framework of a continuum, oromotor tasks sharing some characteristics with speech (i.e., heterogeneous DDK task) should also be impaired in patients with AoS. Method Syllabic rates of a sentence production (SP) task are contrasted with those of homogeneous and heterogeneous DDK tasks in three pathological populations: patients with dysarthria due to Parkinson’s Disease (PD, n = 10) or due to amyotrophic lateral sclerosis (ALS, n = 10) and patients with apraxia of speech (AoS, n = 10); and 30 matched neurotypical controls. Results While patients with PD show similar rates across the SP and the DDK tasks relative to control speakers, patients with ALS display significantly slower rates across all tasks as compared to matched controls. Patients with AoS show reduced performances in the SP and in the heterogeneous DDK task, but not on the repetition of homogeneous syllables. Conclusions The findings of this study confirm that the repetition of heterogeneous syllables shares more principles and properties with speech than the homogeneous DDK task. This dissimilar relationship between speech and the two types of DDK tasks points to the existence of a continuum among oromotor tasks.

Intelligibility Across a Reading Passage: The Effect of Dysarthria and Cued Speaking Styles.

Reading a passage out loud is a commonly used task in the perceptual assessment of dysarthria. The extent to which perceptual characteristics remain unchanged or stable over the time course of a passage is largely unknown. This study investigated crowdsourced visual analogue scale (VAS) judgments of intelligibility across a reading passage as a function of cued speaking styles commonly used in treatment to maximize intelligibility. The Hunter passage was read aloud in habitual, slow, loud, and clear speaking styles by 16 speakers with Parkinson's disease (PD), 30 speakers with multiple sclerosis (MS), and 32 control speakers. VAS judgments of intelligibility from three fragments representing the beginning, middle, and end of the reading passage were obtained from 540 crowdsourced online listeners. Overall passage intelligibility was reduced for the two clinical groups relative to the control group. All speaker groups exhibited intelligibility variation across the reading passage, with trends of increased intelligibility toward the end of the reading passage. For control speakers and speakers with PD, patterns of intelligibility variation across passage reading did not differ with speaking style. For the MS group, intelligibility variation across the passage was dependent on speaking style. The presence of intelligibility variation within a reading passage warrants careful selection of speech materials in research and clinical practice. Results further indicate that the crowdsourced VAS rating paradigm is useful to document intelligibility in a reading passage for different cued speaking styles commonly used in treatment for dysarthria.

Preliminary Results on the Development of the Perception of Spanish /e/ and /ei/ by Heritage Learners vs. L2 Learners of Spanish in the Classroom

This exploratory study gives a first glance at the development of the perception of the Spanish /e/-/ei/ contrast by heritage learners in comparison to that of L2 learners in the classroom. To this end, two types of semester-long, explicit phonetic instruction training are compared: High Phonetic Variability Training (HPVT) with exposure to multiple sources of speech, and regular standalone phonetics courses with low variability of speech input (LPVT). Data from two identical pre-test and post-test ABX perceptual discrimination tasks were obtained from 27 students, as well as 7 control speakers whose primary language is Spanish. Results show that heritage learners perceive the contrast better than L2 learners, and that HPVT significantly improves the perception of the /e/-/ei/ contrast. Although heritage learners perform close to a native ceiling and do not significantly differ from native controls, the improvement from pre-test to post-test is larger in heritage learners enrolled in HPVT than LPVT training. These results suggest that, although the discrimination accuracy of Spanish /e/ and /ei/ is already high for heritage learners at the pre-test stage, High Phonetic Variability Training can be beneficial in the perceptual development of their heritage language, even matching their accuracy to that of native speakers.

"You Say Severe, I Say Mild": Toward an Empirical Classification of Dysarthria Severity.

The main purpose of this study was to create an empirical classification system for speech severity in patients with dysarthria secondary to amyotrophic lateral sclerosis (ALS) by exploring the reliability and validity of speech-language pathologists' (SLPs') ratings of dysarthric speech. Ten SLPs listened to speech samples from 52 speakers with ALS and 20 healthy control speakers. SLPs were asked to rate the speech severity of the speakers using five response options: normal, mild, moderate, severe, and profound. Four severity-surrogate measures were also calculated: SLPs transcribed the speech samples for the calculation of speech intelligibility and rated the effort it took to understand the speakers on a visual analog scale. In addition, speaking rate and intelligible speaking rate were calculated for each speaker. Intrarater and interrater reliability were calculated for each measure. We explored the validity of clinician-based severity ratings by comparing them to the severity-surrogate measures. Receiver operating characteristic (ROC) curves were conducted to create optimal cutoff points for defining dysarthria severity categories. Intrarater and interrater reliability for the clinician-based severity ratings were excellent and were comparable to reliability for the severity-surrogate measures explored. Clinician severity ratings were strongly associated with all severity-surrogate measures, suggesting strong construct validity. We also provided a range of values for each severity-surrogate measure within each severity category based on the cutoff points obtained from the ROC analyses. Clinician severity ratings of dysarthric speech are reliable and valid. We discuss the underlying challenges that arise when selecting a stratification measure and offer recommendations for a classification scheme when stratifying patients and research participants into speech severity categories.

On the lexical representation of compound nouns: Evidence from a picture-naming task with compound targets and gender-marked determiner primes in aphasia

Our study examines the lexical representation and processing of compounds in participants with aphasia (PWA) and language-unimpaired control speakers. Participants were engaged in primed picture-naming in German, a language that marks for grammatical gender. Gender-marked determiners served as primes (dermasc, diefem, dasneut [the]) and noun-noun compounds as targets (e.g., Goldneutfischmasc [goldfish]). Experiment 1 tested whether the compound's constituents are activated at a lexical-syntactic level during production. Primes were gender-congruent either with the morphological head of the target compound (e.g., dermasc for the target Goldneutfischmasc), or its modifier (dasneut for Goldneutfischmasc), or incongruent with both (diefem). Head congruency of prime and target produced strong facilitatory effects across groups. Modifier congruent primes produced contrasting effects. Modifier congruency speeded up picture naming in the controls and PWA with isolated deficits of lexical access (PWA-lex) but they delayed picture naming in PWA with additional deficits of phonological encoding (PWA-pho). Both patterns suggest that the lemmas of both constituents of compound targets and their grammatical gender are activated during compound retrieval, in line with a multiple-lemma representation of compounds. Experiment 2 explored the nature of the observed effects compared to a gender-neutral control condition. While facilitatory effects were shown by PWA-lex and the controls, PWA-pho did not profit from congruent primes but showed inhibitory effects by incongruent primes, exclusively. Inhibitory effects were also attested for the controls but not for PWA-lex. The functional origin of determiner priming effects and their theoretical and clinical implications are discussed in the framework of current accounts.

Sentence types and complexity of spontaneous discourse productions by Cantonese-speakers with traumatic brain injury– a preliminary report

ABSTRACT Previous investigations on sentence production in English-speaking individuals with traumatic brain injury (TBI) have yielded mixed conclusions based on their findings. While some studies found comparable sentence complexity between speakers with TBI and control speakers, others reported more syntactic and lexical errors, reduced sentence complexity, and erroneous word order transpositions in the sentence production of speakers with TBI. These contradictory findings could possibly be due to the use of language measures that were less sensitive to subtle syntactic impairments among speakers with TBI. In this preliminary report, the language samples obtained from 11 Cantonese-speaking participants with mild-moderate TBI in Guangzhou, with a mean age of 37.6 and mean years of education of 10 years, and nine control speakers with a similar age range and education background were analyzed using in-depth linguistic-oriented frameworks adopted from pervious works in Cantonese. The results indicated that the TBI group produced more errors, different varieties of sentence types, and lower syntactic complexity in their sentence production compared with the control group. The findings suggested that the more refined and linguistic-oriented measures used in the present study were more sensitive in identifying the subtle syntactic impairments produced by the participants with TBI.

Listeners' Linguistic Experience Affects the Degree of Perceived Nativeness of First Language Pronunciation.

The aim of this study was to explore if and to what extent Austrian-English late sequential bilinguals who have been living in a second language (L2) environment for several decades are perceived to sound native in their first language (L1) when being compared to monolingual Austrian German (AG) control speakers. Furthermore, this investigation aimed to identify if listeners differ in their judgments of nativeness of L1 pronunciation depending on their own language background. For this purpose, two groups of native Austrian German listeners (N = 30 each), who differed regarding their linguistic background (Austrian German monolingual and Austrian German-English bilingual listeners) were asked to rate spontaneous speech samples produced by Austrian English bilingual and Austrian German monolingual speakers. Results showed that the bilingual L1 speech was perceived to sound overall less native compared to monolingual control speech. It was further observed that the two listener groups significantly differed in their perception of nativeness: Bilingual listeners were overall less likely to judge bilingual L1 pronunciation to sound non-native compared to monolingual listeners. To date, this is the first study to show that listener experience influences their perception of nativeness of L1 pronunciation and, thus, adds a new dimension to the notion of the native speaker.

Two Distinct Clinical Phenotypes of Bulbar Motor Impairment in Amyotrophic Lateral Sclerosis.

Objective: Understanding clinical variants of motor neuron diseases such as amyotrophic lateral sclerosis (ALS) is critical for discovering disease mechanisms and across-patient differences in therapeutic response. The current work describes two clinical subgroups of patients with ALS that, despite similar levels of bulbar motor involvement, have disparate clinical and functional speech presentations.Methods: Participants included 47 healthy control speakers and 126 speakers with ALS. Participants with ALS were stratified into three clinical subgroups (i.e., bulbar asymptomatic, bulbar symptomatic high speech function, and bulbar symptomatic low speech function) based on clinical metrics of bulbar motor impairment. Acoustic and lip kinematic analytics were derived from each participant's recordings of reading samples and a rapid syllable repetition task. Group differences were reported on clinical scales of ALS and bulbar motor severity and on multiple speech measures.Results: The high and low speech-function subgroups were found to be similar on many of the dependent measures explored. However, these two groups were differentiated on the basis of an acoustic measure used as a proxy for tongue movement.Conclusion: This study supports the hypothesis that high and low speech-function subgroups do not differ solely in overall severity, but rather, constitute two distinct bulbar motor phenotypes. The findings suggest that the low speech-function group exhibited more global involvement of the bulbar muscles than the high speech-function group that had relatively intact lingual function. This work has implications for clinical measures used to grade bulbar motor involvement, suggesting that a single bulbar measure is inadequate for capturing differences among phenotypes.

Comparing Lexical Cues in Listener Processing of Dysarthria and Speech in Noise.

Purpose The frequency of a word and its number of phonologically similar neighbors can dramatically affect how likely it is to be accurately identified in adverse listening conditions. This study compares how these two cues affect listeners' processing of speech in noise and dysarthric speech. Method Seven speakers with moderate hypokinetic dysarthria and eight healthy control speakers were recorded producing the same set of phrases. Statements from control speakers were mixed with noise at a level selected to match the intelligibility range of the speakers with dysarthria. A binomial mixed-effects model quantified the effects of word frequency and phonological density on word identification. Results The model revealed significant effects of word frequency (b = 0.37, SE = 0.12, p = .002) and phonological neighborhood density (b = 0.40, SE = 0.12, p = .001). There was no effect of speaking condition (i.e., dysarthric speech vs. speech in noise). However, a significant interaction was observed between speaking condition and word frequency (b = 0.26, SE = 0.04, p < .001). Conclusions The model's interactions indicated that listeners were more strongly influenced by the effects of word frequency when decoding moderate hypokinetic dysarthria as compared to speech in noise. Differences in listener reliance on lexical cues may have important implications for the selection of communication-based treatment strategies for speakers with dysarthria.

Speech rate association with cerebellar white-matter diffusivity in adults with persistent developmental stuttering.

Speech rate is a basic characteristic of language production, which affects the speaker's intelligibility and communication efficiency. Various speech disorders, including persistent developmental stuttering, present altered speech rate. Specifically, adults who stutter (AWS) typically exhibit a slower speech rate compared to fluent speakers. Evidence from imaging studies suggests that the cerebellum contributes to the paced production of speech. People who stutter show structural and functional abnormalities in the cerebellum. However, the involvement of the cerebellar pathways in controlling speech rate remains unexplored. Here, we assess the association of the cerebellar peduncles with speech rate in AWS and control speakers. Diffusion MRI and speech-rate data were collected in 42 participants (23 AWS, 19 controls). We used deterministic tractography with Automatic Fiber segmentation and Quantification (AFQ) to identify the superior, middle, and inferior cerebellar peduncles (SCP, MCP, ICP) bilaterally, and quantified fractional anisotropy (FA) and mean diffusivity (MD) along each tract. No significant differences were observed between AWS and controls in the diffusivity values of the cerebellar peduncles. However, AWS demonstrated a significant negative association between speech rate and FA within the left ICP, a major cerebellar pathway that transmits sensory feedback signals from the olivary nucleus into the cerebellum. The involvement of the ICP in controlling speech production in AWS is compatible with the view that stuttering stems from hyperactive speech monitoring, where even minor deviations from the speech plan are considered as errors. In conclusion, our findings suggest a plausible neural mechanism for speech rate reduction observed in AWS.

Utterance Verification-Based Dysarthric Speech Intelligibility Assessment Using Phonetic Posterior Features

In the literature, the task of dysarthric speech intelligibility assessment has been approached through development of different low-level feature representations, subspace modeling, phone confidence estimation or measurement of automatic speech recognition system accuracy. This paper proposes a novel approach where the intelligibility is estimated as the percentage of correct words uttered by a speaker with dysarthria by matching and verifying utterances of the speaker with dysarthria against control speakers’ utterances in phone posterior feature space and broad phonetic posterior feature space. Experimental validation of the proposed approach on the UA-Speech database, with posterior feature estimators trained on the data from auxiliary domain and language, obtained a best Pearson's correlation coefficient ( $r$ ) of 0.950 and Spearman's correlation coefficient ( $\rho$ ) of 0.957. Furthermore, replacing control speakers’ speech with speech synthesized by a neural text-to-speech system obtained a best $r$ of 0.931 and $\rho$ of 0.961.