Effect of speech task on intelligibility in dysarthria: a case study of Parkinson's disease

This study assessed intelligibility in a dysarthric patient with Parkinson's disease (PD) across five speech production tasks: spontaneous speech, repetition, reading, repeated singing, and spontaneous singing, using the same phrases for all but spontaneous singing. The results show that this speaker was significantly less intelligible when speaking spontaneously than in the other tasks. Acoustic analysis suggested that relative intensity and word duration were not independently linked to intelligibility, but dysfluencies (from perceptual analysis) and articulatory/resonance patterns (from acoustic records) were related to intelligibility in predictable ways. These data indicate that speech production task may be an important variable to consider during the evaluation of dysarthria. As speech production efficiency was found to vary with task in a patient with Parkinson's disease, these results can be related to recent models of basal ganglia function in motor performance.     

Neurolinguistic features of spontaneous language production dissociate three forms of neurodegenerative disease: Alzheimer's, Huntington's, and Parkinson's

An analysis of the temporal (prospective) form (silent and filled hesitations, repetitions, incomplete phrases, context-related comments, interjections), syntactic form, and lexical (retrospective) form (verbal deviations, open and closed class phrases) of spontaneous language production of early and middle stage Alzheimer's, Huntington's, and Parkinson's patients was made. Results showed that the language structure was disrupted in each disease, but in different ways. Temporal interruptions of varying types were frequent in the language of Alzheimer's and Huntington's Disease patients; only long-duration silent hesitations were frequent in Parkinson's language samples. Syntactic complexity was reduced in Huntington's Disease. Verbal paraphasias were found in both the language of Alzheimer's patients, as well as moderately advanced Huntington's patients. Closed class phrases were predominant in the language of Alzheimer's patients and Huntington's patients, and open class phrases in the language of Parkinson's patients. Taken together, the results suggest that (1) there is a unique neurolinguistic profile for spontaneous language production for each neurodegenerative disease, (2) pathology of the neostriatum disrupts syntactic organization, (3) adaptive strategies are used to cope with verbal and speech-motor difficulties, and (4) adaptive strategies fail to be effective with increasing disease severity.     

Speech motor programming in hypokinetic and ataxic dysarthria

It is widely accepted that the cerebellar and basal ganglia control circuits contribute to the programming of movement. Converging evidence from neuroimaging, limb control, and neuropsychological studies suggests that (1) people with cerebellar disease have reduced ability to program movement sequences in advance of movement onset and (2) people with Parkinson's disease are unable to maintain a programmed response or to rapidly switch between responses. Despite a substantial supporting literature, no studies have addressed these potential areas of speech programming disruption for speakers with ataxic and hypokinetic dysarthria. Control participants and adults with dysarthria completed speech reaction time protocols designed to capture these aspects of utterance preparation. Results provided initial support for processing deficits in speakers with ataxic and hypokinetic dysarthria that are separable from motor execution impairments.     

The semantics of prosody: acoustic and perceptual evidence of prosodic correlates to word meaning

This investigation examined whether speakers produce reliable prosodic correlates to meaning across semantic domains and whether listeners use these cues to derive word meaning from novel words. Speakers were asked to produce phrases in infant-directed speech in which novel words were used to convey one of two meanings from a set of antonym pairs (e.g., big/small). Acoustic analyses revealed that some acoustic features were correlated with overall valence of the meaning. However, each word meaning also displayed a unique acoustic signature, and semantically related meanings elicited similar acoustic profiles. In two perceptual tests, listeners either attempted to identify the novel words with a matching meaning dimension (picture pair) or with mismatched meaning dimensions. Listeners inferred the meaning of the novel words significantly more often when prosody matched the word meaning choices than when prosody mismatched. These findings suggest that speech contains reliable prosodic markers to word meaning and that listeners use these prosodic cues to differentiate meanings. That prosody is semantic suggests a reconceptualization of traditional distinctions between linguistic and nonlinguistic properties of spoken language.     

The influence of speaking rate on articulatory hypokinesia in parkinsonian dysarthria

This study addressed the question of whether or not speaking rate influences articulatory hypokinesia in dysarthria associated with Parkinson's disease. Analyses of parkinsonian speech samples revealed mean speaking rates consistent with normal controls. Thus, speaking rate was not abnormal overall in this group of dysarthric subjects. Kinematic analyses of labial displacement amplitude, peak instantaneous velocity, and movement time were made during repetitive syllable production spoken at two speaking rates: 3-5 syllables/sec and 5-7 syllables/sec. The results suggested that labial movements were normal at the slower of the two speaking rates. Conversely, labial movements became hypokinetic as speaking rate increased to the rate consistent with conversational speech. These findings provide a physiologic basis for the perception of hypokinetic dysarthria in Parkinson's disease and suggest that speaking rate may be an important control variable contributing to articulatory hypokinesia in Parkinson's disease. Moreover, these findings provide quantitative evidence that articulatory hypokinesia plays a dominant role in the perception of parkinsonian dysarthria.     

Productive syntax abilities in Huntington's and Parkinson's diseases

This study examined syntactic changes in the spoken discourse of patients with Huntington's (HD) or Parkinson's disease (PD) and explored possible relationships between their syntactic changes and concomitant cognitive and motoric symptoms. Patient and control groups participated in a conversational discourse activity and completed a battery of standardized speech and cognitive tests. The HD group used shorter and fewer grammatically complete utterances than their healthy, age-matched peers, whereas there were no significant syntactic differences between PD patients and their healthy, age-matched peers or between PD and HD patients. Productive syntax abilities in HD and PD were meaningfully related to both neuropsychological and motor speech changes. These findings indicate that patients with subcortical disease, at least those with HD, may present with language production deficits and that these deficits are most likely the product of not only motor speech limitations (i.e., dysarthria) but also underlying cognitive impairments.     

Attention orienting effects of hesitations in speech: evidence from ERPs

Filled-pause disfluencies such as um and er affect listeners' comprehension, possibly mediated by attentional mechanisms (J. E. Fox Tree, 2001). However, there is little direct evidence that hesitations affect attention. The current study used an acoustic manipulation of continuous speech to induce event-related potential components associated with attention (mismatch negativity [MMN] and P300) during the comprehension of fluent and disfluent utterances. In fluent cases, infrequently occurring acoustically manipulated target words gave rise to typical MMN and P300 components when compared to nonmanipulated controls. In disfluent cases, where targets were preceded by natural sounding hesitations culminating in the filled pause er, an MMN (reflecting a detection of deviance) was still apparent for manipulated words, but there was little evidence of a subsequent P300. This suggests that attention was not reoriented to deviant words in disfluent cases. A subsequent recognition test showed that nonmanipulated words were more likely to be remembered if they had been preceded by a hesitation. Taken together, these results strongly implicate attention in an account of disfluency processing: Hesitations orient listeners' attention, with consequences for the immediate processing and later representation of an utterance.     

Speech timing in Parkinson''s and Huntington''s disease

The purpose was to determine the effects of two different basal ganglia diseases on speech planning, initiation, and production. Patients with Parkinson's Disease (PD) and Huntington's Disease (HD) were compared with normal subjects on speech timing tasks. Speech reaction time was unimpaired, while changes in duration at different speech rates were affected differently in the two patient groups. In HD, changes in the duration of syllables, of pauses between phrases, and of sentences were all reduced, while in PD only the control of sentence duration was impaired. The HD patients had reduced syllable repetition rates, but both patient groups maintained their repetition rates over 5 sec. The ratios of word to phrase time, and of phrase to sentence time, remained constant across regular and fast speaking rates and did not differ from normal in either patient group. The results suggest that PD and HD patients are not impaired in speech planning or initiation, but have poor control over the duration of speech events.     

It's the way that you, er, say it: hesitations in speech affect language comprehension

Everyday speech is littered with disfluency, often correlated with the production of less predictable words (e.g., Beattie & Butterworth [Beattie, G., & Butterworth, B. (1979). Contextual probability and word frequency as determinants of pauses in spontaneous speech. Language and Speech, 22, 201-211.]). But what are the effects of disfluency on listeners? In an ERP experiment which compared fluent to disfluent utterances, we established an N400 effect for unpredictable compared to predictable words. This effect, reflecting the difference in ease of integrating words into their contexts, was reduced in cases where the target words were preceded by a hesitation marked by the word er. Moreover, a subsequent recognition memory test showed that words preceded by disfluency were more likely to be remembered. The study demonstrates that hesitation affects the way in which listeners process spoken language, and that these changes are associated with longer-term consequences for the representation of the message.     

A computational model of word segmentation from continuous speech using transitional probabilities of atomic acoustic events

Word segmentation from continuous speech is a difficult task that is faced by human infants when they start to learn their native language. Several studies indicate that infants might use several different cues to solve this problem, including intonation, linguistic stress, and transitional probabilities between subsequent speech sounds. In this work, a computational model for word segmentation and learning of primitive lexical items from continuous speech is presented. The model does not utilize any a priori linguistic or phonemic knowledge such as phones, phonemes or articulatory gestures, but computes transitional probabilities between atomic acoustic events in order to detect recurring patterns in speech. Experiments with the model show that word segmentation is possible without any knowledge of linguistically relevant structures, and that the learned ungrounded word models show a relatively high selectivity towards specific words or frequently co-occurring combinations of short words.     

Are Words Easier to Learn From Infant‐ Than Adult‐Directed Speech? A Quantitative Corpus‐Based Investigation

We investigate whether infant‐directed speech (IDS) could facilitate word form learning when compared to adult‐directed speech (ADS). To study this, we examine the distribution of word forms at two levels, acoustic and phonological, using a large database of spontaneous speech in Japanese. At the acoustic level we show that, as has been documented before for phonemes, the realizations of words are more variable and less discriminable in IDS than in ADS. At the phonological level, we find an effect in the opposite direction: The IDS lexicon contains more distinctive words (such as onomatopoeias) than the ADS counterpart. Combining the acoustic and phonological metrics together in a global discriminability score reveals that the bigger separation of lexical categories in the phonological space does not compensate for the opposite effect observed at the acoustic level. As a result, IDS word forms are still globally less discriminable than ADS word forms, even though the effect is numerically small. We discuss the implication of these findings for the view that the functional role of IDS is to improve language learnability.     

Reading and spontaneous speaking fundamental frequency of young Arabic men for Arabic and English languages: a comparative study

Speaking fundamental frequency (SFF), the average fundamental frequency (lowest frequency of a complex periodic sound) measured over the speaking time of a vocal or speech task, is a basic acoustic measure in clinical evaluation and treatment of voice disorders. Currently, there are few data on acoustic characteristics of different sociolinguistic groups, and no published data on the fundamental frequency characteristics of Arabic speech. The purpose of this study was to obtain preliminary data on the SFF characteristics of a group of normal speaking, young Arabic men. 15 native Arabic men (M age = 23.5 yr., SD=2.5) as participants received identical experimental treatment. Four speech samples were collected from each one, Arabic reading, Arabic spontaneous speech, English reading, and English spontaneous speech. Speaking samples, analyzed using the Computerized Speech Lab, showed no significant difference for mean SFF between language and type of speech and none for mean SFF between languages. A significant difference in the mean SFF was found between the types of speech. The SFF used during reading was significantly higher than that for spontaneous speech. Also Arabic men had higher SFF values than those previously reported for young men in other linguistic groups. SFF then might differ among linguistic, dialectical, and social groups and such data may provide clinicians information useful in evaluation and management of voice.     

Blind Speakers Show Language‐Specific Patterns in Co‐Speech Gesture but Not Silent Gesture

Sighted speakers of different languages vary systematically in how they package and order components of a motion event in speech. These differences influence how semantic elements are organized in gesture, but only when those gestures are produced with speech (co‐speech gesture), not without speech (silent gesture). We ask whether the cross‐linguistic similarity in silent gesture is driven by the visuospatial structure of the event. We compared 40 congenitally blind adult native speakers of English or Turkish (20/language) to 80 sighted adult speakers (40/language; half with, half without blindfolds) as they described three‐dimensional motion scenes. We found an effect of language on co‐speech gesture, not on silent gesture—blind speakers of both languages organized their silent gestures as sighted speakers do. Humans may have a natural semantic organization that they impose on events when conveying them in gesture without language—an organization that relies on neither visuospatial cues nor language structure.     

Impaired perception of vocal emotions in Parkinson's disease: influence of speech time processing and executive functioning

Little is known about the underlying dimensions of impaired recognition of emotional prosody that is frequently observed in patients with Parkinson's disease (PD). Because patients with PD also suffer from working memory deficits and impaired time perception, the present study examined the contribution of (a) working memory (frontal executive functioning) and (b) processing of the acoustic parameter speech rate to the perception of emotional prosody in PD. Two acoustic parameters known to be important for emotional classifications (speech duration and pitch variability) were systematically varied in prosodic utterances. Twenty patients with PD and 16 healthy controls (matched for age, sex, and IQ) participated in the study. The findings imply that (1) working memory dysfunctions and perception of emotional prosody are not independent in PD, (2) PD and healthy control subjects perceived vocal emotions categorically along two acoustic manipulation continua, and (3) patients with PD show impairments in processing of speech rate information.     

The contribution of apraxic speech to working memory deficits in Parkinson's disease

This article links two formerly separate areas of research associated with Parkinson's disease (PD): speech and memory. It is proposed that speech deficits occur in PD not merely at the level of muscular control, as is commonly termed dysarthria, but also at the level of speech planning and programming, more aptly described as a form of apraxia. It is further argued that PD patient groups exhibit small deficits in verbal span, and the link between apraxic speech and verbal span is elucidated via Baddeley's (1986) model of working memory. An experiment is described in which aspects of speech of 36 PD and 43 healthy control subjects were rated and classified, and measures of span and articulation rate for words of different syllable lengths were taken. Twenty-three PD subjects had dysarthric speech, while 14 of them had apraxic speech, which was associated with lower memory span scores for longer words. It is concluded that apraxic speech can be a source of reduced memory span in PD. In addition to implications for rehabilitation and therapeutic work with PD sufferers, these findings advance our theoretical understanding of the Parkinsonian syndrome.     

Asynchronous language acquisition in developmental dysphasia

A longitudinal study was conducted to document and compare evolution of children with linguistic acquisition impairment. To determine whether development of the analytic mechanisms underlying linguistic processing occured in similar fashion, two children with mixed developmental dysphasia were assessed from 4 to 5:6 years of age with psycholinguistic tests at 6-months interval. Spontaneous speech and language production (consonant repertory in initial word position, MLU, and lexical diversity) were investigated in a standardized symbolic play context. The phonologic and lexico-morphologic evolution analyses revealed a marked improvement in motor control of phonology and in the application of morphosyntaxic rules in child 1, whereas child 2 was still impaired in phonology and morphosyntax. The singular developmental changes in spontaneous speech results indicate dynamic relationships between various language production facets and variability in the kind of deficit and lexical automation presented by these children. These contrasts in the evolution of language production profiles between child 1 and child 2 also underline the importance of longitudinal studies in the analysis of the atypical linguistic processing paths used by children with developmental dysphasia.     

Start-up Rhetoric in Eight Speeches of Barack Obama

Our purpose in the following was to investigate the start-up rhetoric employed by U.S. President Barack Obama in his speeches. The initial 5 min from eight of his speeches from May to September of 2009 were selected for their variety of setting, audience, theme, and purpose. It was generally hypothesized that Barack Obama, widely recognized for the excellence of his rhetorical performance, would pursue both constant and variable strategies in his effort to establish contact with his audience. More specifically, it was hypothesized that the make-up of the audience—primarily native or non-native speakers of English—would be a prominent independent variable. A number of temporal and verbal measures were used as dependent variables. Variations were evident in mean length in syllables and duration in seconds of utterances (articulatory phrases), articulation rate in syllables per second of ontime, mean duration of silent pauses in seconds, and frequency of fillers, hesitations, colloquial words and phrases, introductory phrases, and 1st person singular pronominals. Results indicated that formality versus informality of the setting and presence or absence of a teleprompter were more prominent than native versus non-native audiences. Our analyses confirm Obama’s skillfulness in challenging and variable settings and clearly detect orderliness and scientific generalizability in language use. The concept of orality/literacy provides a theoretical background and emphasizes dialogical interaction of audience and speaker.