Challenges with the kinematic analysis of neurotypical and impaired speech : measures and models

A common goal of kinematic studies on disordered speech is the identification of speech motor impairments that negatively impact speech function. Although it is well-known that the kinematic contours of speakers with speech disorders often deviate considerably from those of neurotypical speakers, systematic quantitative assessments of these impairment-related movement disturbances remain challenging. Kinematic measurement approaches are commonly grounded in models and theories that have emerged exclusively from observations of healthy speakers. However, often these models cannot accommodate the deviant articulatory behaviors of speakers with speech motor impairment. In the present paper, we address this problem. By considering noise as a factor in Articulatory Phonology/Task Dynamics (AP/TD), we can account for articulatory behaviors that are known to occur in healthy speakers (e.g., during slow speech) as well as in speakers with motor speech impairments. In a proof of concept, we descriptively compare modeled articulatory behaviors that include noise at various levels with empirical data. We view such an extension of the AP/TD as a first step towards a more comprehensive speech production model that can serve as a theoretical framework to study the speech production mechanism in healthy speakers and speakers with motor speech impairments

Prosodic prominence in parkinsonian speech : a dynamical approach

In the present study, we investigate dynamic changes in prosodic highlighting strategies in PD patients and compare them to the productions of neurotypical speakers. Therefore, we compare the production of target words in divergent focus structure, contrastive focus and background. We recorded 40 German speakers: 20 patients with idiopathic Parkinson in medication ON condition, 14 males and 6 females, aged between 54 - 80 and 20 healthy aged and gender matched controls. All speakers were classified in terms of duration of the disorder, severity of the disorder, motoric activity level (UPDRS III, [6]), level of cognition and speech problems in terms of dysarthria. As speech material, we used a question-answer scenario presented on a computer screen to manipulate focal structure by means of contextualizing contexts. Nine target words were placed in either contrastive focus or background position in sentences such as (“The fly has touched the green nose.”) related to pictures on a computer screen [cf. fig.1]. Target words were always disyllabic (CV.CV structure), containing one of the three long vowels /i:/, /a:/ or /o:/, in the stressed syllable, such as /na:z@/. In total, we recorded 1440 tokens (9 target words x 40 speakers x 2 focus structures x 2 adjectives). For acoustic measurements, we analyzed the voice range, syllable duration, formant means and contours, the mean intensity and the F0 contours in terms of pitch height and tonal onglide [7]. For the upcoming conference, the results of all intonational and articulatory variables will be presented. We will discuss how much variation is tolerated in a dynamical system of prosodic prominence before the expression of prosodic functions is getting instable

Cognitive skills and prominence production : highlighting prominent elements in the speech of patients with Parkinson's disease

Patients with idiopathic parkinsonism suffer from a neurodegenerative disorder of the nervous system. Due to a progressive loss of dopaminergic cells in the substantia nigra patients with Parkinson’s disease (PD) develop problems with motor and non-motor functions. On the motor level the dysfunctions defect the voluntary movements and lead to symptoms like: rigidity, resting tremor and bradykinesia [1]. On the level of cognition PD patients have problems with the executive functions, cognitive flexibility, working memory and control of attention [2]. Furthermore, the speech system gets affected which often leads to dysarthric speech. This hypokinetic dysarthria impacts the phonation, articulation and the respiratory system. The speech deficits include monoloudness, monopitch, reduced stress, imprecise articulation, variability of speech rate, disfluencies and voice tremor [3, 4, 5].PD affects communication as well as other related functions such as cognition, but complex prosodic aspects such as focus marking are less well studied. Prominence marking in German requires changes in intonation and articulation [6]. Speakers use multiple cues in the phonetic domain to regulate prosodic marking [7], e.g. modulation of F0 and syllable duration. Furthermore, there is insufficient literature on the impact of cognition on these phonetic aspects of prominence marking. The aim of this study is to analyse how prosodic prominence correlates with motoric and cognitive abilities in patients with Parkinson’s disease in the complex process of speech production

Task-based profiles of language impairment and their relationship to cognitive dysfunction in Parkinson’s disease

Objective: Parkinson's Disease (PD) is associated with both motor and non-motor problems, such as cognitive impairment. Particular focus in this area has been on the relationship between language impairment and decline in other cognitive functions, with the literature currently inconclusive on how the nature and degree of language impairment relate to cognition or other measures of disease severity. In addition, little information is available on how language problems identified in experimental task set-ups relate to competency in self-generated language paradigms such as picture description, monologues or conversations. This study aimed to inform clinical management of language impairment in PD by exploring (1) language performance across a range of experimental as well as self-generated language tasks, (2) how the relationship between these two aspects might be affected by the nature of the cognitive and language assessment; and (3) to what degree performance can be predicted across the language tasks. Methods: 22 non-demented people with PD (PwPD) and 22 healthy control participants performed a range of cognitive and language tasks. Cognitive tasks included a screening assessment in addition to tests for set shifting, short term memory, attention, as well as letter and category fluency. Language was investigated in highly controlled grammar tasks as well as a Sentence Generation and a Narrative. Results: The study highlighted impaired ability in set-shifting and letter fluency in the executive function tasks, and a higher rate of grammatical and lexical errors across all language tasks in the PD group. The performance in the grammar task was linked to set shifting ability, but error rates in Sentence Generation and Narrative were independent of this. There was no relevant relationship between performances across the three language tasks. Conclusions: Our results suggest that there is a link between executive function and language performance, but that this is task dependent in non-demented PwPD. This has implications for the management of language impairment in PD, both for assessment and for designing effective interventions

Compensation in Time and Space: Prominence Marking in Aging and Disease

This study aims to explore the effects of healthy aging and Parkinson’s disease on speech motor performance. One area of speech production which requires fine speech motor control is prominence marking. Therefore, strategies of prominence marking of three speaker groups with four speakers each were investigated: younger speakers, older speakers, and speakers with Parkinson’s disease (PD). Acoustic and articulatory data were collected. Speech data were analyzed focusing on prominence-related adjustments of vowel production and tongue body movements in the temporal and spatial domain. Longer durations, varying initiation of the tongue movements and smaller vowel sizes in older speakers and in speakers with PD were found compared to younger speakers. The data indicate further that all speaker groups mark prominence by changing relevant parameters in the vowel articulation; however, strategies seem to differ between the groups: (i) in the temporal domain, articulatory movement durations increase with age and are further prolonged in speakers with PD; (ii) in the spatial domain, the articulation space is resized by the older speakers in a non-symmetrical way, while no systematic vocalic modulations were found for speakers with PD. To conclude, the speech system seems to be affected by age and disease, but speakers develop compensatory strategies to counteract influences in the spatial domain