Speech Production Deficits Research Articles

Can articulatory behavior in motor speechdisorders be accounted for by theories of normal speech production?

This paper deals with the relationship of speech production theoriesto articulatory behavior in motor speech disorders. The ability of translation and gesture theories to account for some selected facts of motor speech disorders is first considered, followed by a report of a small-scale experiment designed to demonstrate a specific application of certain aspects of gesture theory to articulatory variability in apraxia of speech. The results of this experiment seem to indicate that a gesture perspective on the speech production deficit in motor speech disorders may yield important insights for both normal and disordered speech production.

Neurobiological Basis of Speech: A Case for the Preeminence of Temporal Processing

In this paper we present evidence supporting the hypothesis that a basic temporal processing impairment in language-impaired children underlies their inability to integrate sensory information that converges in rapid succession in the central nervous system. We provide data showing that this deficit is pansensory; that is, affects processing in multiple sensory modalities, and also affects motor output within the millisecond time frame. We also provide data that links these basic temporal integration deficits to specific patterns of speech perception and speech production deficits in language-impaired children. We suggest that these basic temporal deficits cause a cascade of effects starting with disruption of the normal development of an otherwise effective and efficient phonological system. We propose further that these phonological processing deficits result in subsequent failure to learn to speak and to read normally. That is, both the language and reading problems have their basis in deficiently esta...

On the Notion of a "Subtle Phonetic Deficit" in Fluent/Posterior Aphasia

Phonetic investigations in the past decade or so have reported instances of a "subtle phonetic deficit" in the fluent aphasias, thereby challenging the traditional dichotomy of a motoric deficit characterizing the nonfluent aphasias and a selection deficit characterizing the fluent aphasias. This paper critically reviews the acoustic, physiological, and perceptual studies which have attempted to examine this phenomenon. These investigations have been evaluated in terms of differences in subject populations, task demands, subjects′ performance, and problematic interpretations. Suggestions are offered for an experimental design which can help us operationalize this term and help us to better understand the speech production deficit in fluent aphasic patients.

Impairments of speech production and speech perception in aphasia

The basis of speech production and speech perception deficits in aphasia relates to implementation and access rather than to the underlying representation or knowledge base of the sound structure of language. Speech production deficits occur on the phonological level in which the incorrect phonological form of the word is selected but is implemented correctly, and the phonetic level in which the correct sound segments are selected but articulatory implementation is impaired. Phonological deficits emerge regardless of lesion site, whereas phonetic deficits have a specific localized neuroanatomical substrate. Phonetic deficits are not linguistic but affect particular articulatory movements. Speech perception impairments emerge in nearly all aphasic patients, suggesting that the neural basis for speech perception is broadly distributed in the language hemisphere. The impairment reflects the misperception of phonetic features rather than a deficit in the auditory processing of speech and emerges particularly as the sound properties of speech contact the lexicon.

Neurobiological basis of speech: a case for the preeminence of temporal processing.

In this paper we present evidence supporting the hypothesis that a basic temporal processing impairment in language-impaired children underlies their inability to integrate sensory information that converges in rapid succession in the central nervous system. We provide data showing that this deficit is pansensory; that is, affects processing in multiple sensory modalities, and also affects motor output within the millisecond time frame. We also provide data that links these basic temporal integration deficits to specific patterns of speech perception and speech production deficits in language-impaired children. We suggest that these basic temporal deficits cause a cascade of effects starting with disruption of the normal development of an otherwise effective and efficient phonological system. We propose further that these phonological processing deficits result in subsequent failure to learn to speak and to read normally. That is, both the language and reading problems have their basis in deficiently esta...

Rate of Speech Effects in Aphasia: Voice Onset Time

This study investigated the ability to produce appropriate voice onset time (VOT) contrasts under conditions of rate modulation in groups of nonfluent aphasic subjects, fluent aphasic subjects, and nonneurological controls. Acoustic analyses of the consonants [b d g p t k] produced in the context of the vowels [i e a o u] at two different rates of speech revealed that normal subjects′ VOTs were significantly shorter at the fast rate of speech relative to the slow/normal rate, as expected. In addition, the rate change had a significantly greater effect on voiceless stops as compared to voiced and on velar consonants as compared to labials and alveolars. The nonfluent aphasic patients exhibited a similar pattern except that no differences in magnitude of rate-related changes were found across place of articulation. Further, similar to previous studies, the nonfluent aphasic patients produced voiced and voiceless consonants with somewhat overlapping VOT distributions, indicating an impairment in temporal integration in these subjects. Finally, the fluent aphasic patients demonstrated a surprisingly aberrant pattern of results, with VOTs under the fast condition shorter than under the slow, but no differences in magnitude of change across place of articulation or voicing categories. The results are discussed in relation to the nature of speech production deficits in both nonfluent and fluent aphasic patients. Implications for remediation are considered.

An Acoustic Analysis of Rate of Speech Effects on Vowel Production in Aphasia

The present investigation examined the production of tense and lax vowel duration differences at two speaking rates in the speech of 10 nonfluent aphasics, 8 fluent aphasics, and 10 normal control subjects. Subjects produced four repetitions of each of the vowels [i e æ o u I ϵ υ Λ] at each speaking rate. Acoustic analyses revealed that subjects in all three groups were able to manipulate overall rate of speech. In addition, normal controls and fluent aphasic subjects produced vowels under the fast rate condition which were significantly shorter than those under the slow rate condition. Despite a change in overall speaking rate, the nonfluent aphasics did not exhibit a significant difference in vowel duration at the two rates of speech, suggesting a deficit in the implementation of this temporal parameter. Both normal controls and fluent aphasic patients produced nonoverlapping distributions of tense and lax vowels at both speaking rates. In contrast, the nonfluent aphasics demonstrated a great deal of overlap in the distribution of tense and lax vowel durations at the fast rate. Results are discussed in relation to the nature of the speech production deficits in nonfluent and fluent aphasic patients.

Speech production, syntax comprehension, and cognitive deficits in Parkinson's disease

Speech samples were obtained that were analyzed for voice onset time (VOT) for 40 nondemented English speaking subjects, 20 with mild and 20 with moderate Parkinson's disease. Syntax comprehension and cognitive tests were administered to these subjects in the same test sessions. VOT disruptions for stop consonants in syllable initial position, similar to those noted for Broca's aphasia, occurred for nine subjects. Longer response times and errors in the comprehension of syntax as measured by the Rhode Island Test of Sentence Comprehension (RITLS) also occurred for these subjects. Anovas indicate that the VOT overlap subjects had significantly higher syntax error rates and longer response times on the RITLS than the VOT nonoverlap subjects— F(1, 70) = 12.38, p < 0.0008; F(1, 70) = 7.70, p < 0.007, respectively. The correlation between the number of VOT timing errors and the number of syntax errors was significant. ( r = 0.6473, p < 0.01). VOT overlap subjects also had significantly higher error rates in cognitive tasks involving abstraction and the ability to maintain a mental set. Prefrontal cortex, acting through subcortical basal ganglia pathways, is a component of the neural substrate that regulates human speech production, syntactic ability, and certain aspects of cognition. The deterioration of these subcortical pathways may explain similar phenomena in Broca's aphasi. Results are discussed in relation to “modular” theories.

Formant trajectory characteristics of males with amyotrophic lateral sclerosis.

The purpose of this study was to describe the formant trajectories produced by males with amyotrophic lateral sclerosis (ALS), a degenerative neuromuscular disease that is typically associated with dysarthria. Formant trajectories of 25 males with ALS and 15 neurologically normal geriatric males were compared for 12 words selected from the speech intelligibility task developed by Kent et al. [J. Speech. Hear. Disord. 54, 482-499 (1989)]. The results indicated that speakers with ALS (1) produced formant transitions having shallower slopes than transitions of normal speakers, (2) tended to produce exaggerations of formant trajectories at the onset of vocalic nuclei, and (3) had greater interspeaker variability of formant transition characteristics than normal speakers. Within the group of ALS speakers, those subjects who were less than 70% intelligible produced distinctly more aberrant trajectory characteristics than subjects who were more than 70% intelligible. ALS subjects who were less than 70% intelligible produced many trajectories that were essentially flat, or that had very shallow slopes. These results are discussed in terms of the speech production deficit in the dysarthria associated with ALS, and with respect to the potential influence of aberrant trajectories on speech intelligibility.

Interictal language functioning in chronic epilepsy

This paper reviews research studies in relation to interictal language functioning in chronic epilepsy. Areas covered include verbosity, language dominance, the impact of surgery and hypergraphia. Speech production deficits are not considered. A survey of language skills by the authors of 60 patients with intractable epilepsy is outlined. The results demonstrated a high incidence of language problems. The paucity of research in this area is discussed together with possibilities for future research endeavours.

Spectral characteristics for place of articulation in the speech of young normal, moderately and profoundly hearing-impaired French Canadians

A group of 10 moderately hearing-impaired children aged 7-10 years (five boys, five girls), 10 profoundly hearing-impaired children (five boys, five girls), and 10 age-matched normal control subjects (five boys, five girls), were recorded producing the six occlusives / p t k b d g / before the vowel /a/. Five productions were elicited from each child for a total of 30 potential correct productions each. LPC spectral analyses were performed at the moment of release (the burst) to determine the degree to which Blumstein and Stevens' (1979) spectral place-of-articulation features were present in the speech of these normal and hearing-impaired children, and whether there were differences between groups. A static 'centroid' analysis was also performed. Results reveal that the moderately hearing-impaired children's productions were not significantly different from those of the normal controls, but that some aspects of the profoundly hearing-impaired children's productions did differ from those of the moderately hearing-impaired and normal children. The relationship between degree of hearing loss and severity of speech production deficits is discussed. Implications of the results for remediation are also considered.

Temporal dimensions of consonant and vowel production: An acoustic and CT scan analysis of aphasic speech

This study explored a number of temporal (durational) parameters of consonant and vowel production in order to determine whether the speech production impairments of aphasics are the result of the same or different underlying mechanisms and in particular whether they implicate deficits that are primarily phonetic or phonological in nature. Detailed analyses of CT scan lesion data were also conducted to explore whether more specific neuroanatomical correlations could be made with speech production deficits. A series of acoustic analyses were conducted including voice-onset time, intrinsic and contrastive fricative duration, and intrinsic and contrastive vowel duration as produced by Broca's aphasics with anterior lesions (A patients), nonfluent aphasics with anterior and posterior lesions (AP patients), and fluent aphasics with posterior lesions (P patients). The constellation of impairments for the anterior aphasics including both the A and AP patients suggests that their disorder primarily reflects an inability to implement particular types of articulatory gestures or articulatory parameters rather than an inability to implement particular phonetic features. They display impairments in the implementation of laryngeal gestures for both consonant and vowel production. These patterns seem to relate to particular anatomical sites involving Broca's area, the anterior limb of the internal capsule, and the lowest motor cortex areas for larynx and tongue. The posterior patients also show evidence of subtle phonetic impairments suggesting that the neural instantiation of speech may require more extensive involvement, including the perisylvian area, than previously suggested.

Delineation of single‐word semantic comprehension deficits in aphasia, with anatomical correlation

In 3 of 18 aphasic patients pure deficits in semantic comprehension at the single-word level were defined through a series of tasks that excluded possible confounding deficits in auditory perception, visual perception, or speech production. In these pure cases, deficits were found at the superordinate, equivalence, and subordinate levels of single-word semantic processing. Pure semantic deficits were found to be correlated with damage to the left posterior temporal and inferior parietal region; patients whose damage spared this area did not evince such deficits, and the converse was also true. This study confirms the existence of separable deficits in semantic comprehension and points conclusively to the left posterior temporal and inferior parietal region as being critical for semantic processing. This anatomical localization is in keeping with anatomical studies from nonhuman primates, suggesting that these regions may be concerned with multimodal processing and integration of language.

Acoustic analysis of intra-word syllabic timing relations in anterior aphasia

A study was conducted to explore intra-word syllabic timing relations in anterior, non-fluent aphasic patients. Ten sets of three words of increasing length (e.g. “sleep,” “sleepy,” sleepiness”) were elicited from four non-fluent aphasic subjects. Acoustic analyses revealed that, overall, the aphasic patients produced monosyllabic root words with longer durations than those root words embedded in multisyllabic utterances. This general pattern was consistent with that for normal subjects reported in the literature (Lehiste 1972). However, the aphasic patients exhibited anomalous results for root word durations in the three-syllable condition. That is, root word durations were increased in the three-syllable compared to the two-syllable condition — a pattern which contrasts with that of normal subjects. Results are discussed in relation to theories which attempt to characterize the speech production deficit in anterior aphasia.

Speech production deficits in developmental dyslexia.

In this study, dyslexic and normal subjects rapidly repeated a series of phonologically complex and simple phrases. Dyslexic subjects repeated the phrases at a significantly slower rate and, in the complex condition, made significantly more errors. An examination of errors suggested that dyslexics may have difficulties in the planning stage of speech production. Findings are discussed in reference to other phonological deficits and oral reading problems in dyslexia.

Sentence comprehension, syntax and vowel duration in aged people

The comprehension of English syntax was tested for 29 people, aged 71–93 years, using the Rhode Island Test of Language Structure (Engen and Engen, 1983). Nineteen of the subjects were native monolingual speakers of English or bilingual English/Yiddish speakers, ten had acquired English as a second or third language. The native monolingual/bilingual group made 20% fewer errors than the second-language group. Although some individuals had high error rates, there was no consistent age-related increase in syntactic errors for the native speakers of English. Vowel duration was determined for 24 subjects. Older speakers tended to have longer vowel durations, but individual differences override this trend. The subjects who had the highest syntactic error rates produced longer vowels. The effects are consistent with deficits in comprehension and slower speech production deriving from particular disease processes rather than from ageing, in itself. They may be effects of decreased output of the neurotransmitter d...

Differential responding to content and intonation components of a complex auditory stimulus by nonverbal and echolalic autistic children

Anecdotal and scientific reports of the speech of autistic children suggest a possible differential responsiveness to limited components of speech stimuli. Previously nonverbal children who acquire speech seem to acquire content, but their speech is dysprosic, characterized by inappropriate intonation, pitch, rhythm, and modulation. In contrast, echolalic autistic children often display modulation and varied intonation but may demonstrate no comprehension of the verbal stimulus being echoed. The present experiment was conducted to systematically determine whether echolalic and nonverbal autistic children respond overselectively to the intonation or to the content of a complex auditory stimulus differing along these two dimensions. Ten autistic children (five echolalic and five nonverbal) and six normal children, matched for MA, were trained to bar press at the sound of an auditory complex stimulus designated as S+ and to withhold response to an auditory complex stimulus designated as S-. The auditory complex stimulus consisted of two components, content and intonation. Test trials consisting of various combinations of the intonation and content components were then presented. Results indicated that whereas the normal children responded to both components or to content, the nonverbal children showed evidence of selectively responding to content, and the echolalic children showed evidence of selectively responding to intonation. These results are discussed in terms of relating autistic stimulus overselectivity to deficits in speech production and to implications for designing language training programs for these children.

On the evolution of human syntactic ability. Its pre-adaptive Bases—Motor control and speech

The evolution of the particular, species-specific, neural substrate that underlies human syntactic and phonologic ability may be the result of two stages of pre-adaptation involving automatization for complex goal-directed motor control. The neural mechanisms of the non-human primate brain that evolved to enhance the automatization of orofacial motor control appear to be the homologue of Broca's area in the human brain. These mechanisms may have been preadapted in certain hominids for the evolution of neural mechanisms adapted for automatized speech articulation, matched to the development of the human supralaryngeal vocal tract. Recent data show that the articulatory maneuver that underly the production of human speech appear to be the most complex that human beings master. The selective pressure for the automatization of articulatory activity for speech production on the neural mechanisms of Broca's area in the hominids ancestral to anatomically modern homo sepiens yielded a neural substrate suited to complex rule-governed behavior in the linguistic domains of phonology and syntax. The theory predicts correlations between the speech production and syntactic deficits of chimpanzees, as well as correlations between syntactic deficits and speech production deficits in aphasia, and some instances of deafness. The development of patterned motor activity and syntactic and phonologic ability in human children may also be connected.

More on the speech production deficit associated with Parkinson's disease

For certain patients with Parkinson's disease, we have shown that aspects of vowel production inferred from acoustic analysis are consistent with the akinetic and bradykinetic characteristics of Parkinsonian limb movements [G. Weismer and M.D.Z. Kimelman, J. Acoust. Soc. Am. Suppl. 1 77, S87 (1985)]. Because Parkinsonian dysarthria is often characterized by abnormally fast articulation rates, it is possible that some of the reduced transition extents and rates observed for Parkinson's patients do not reflect directly the nature of the speech movement disorder, but rather are by‐products of the abnormally fast rates. To address this issue, vowel transition data will be presented from three groups of speakers (Parkinson's patients, young adults, and geriatrics) who tend to separate on the variable of articulation rate. In addition, the effect of fast rate productions on transition extents and rates in normal speakers will be discussed as a potential simulation of Parkinsonian dysarthria. [Work supported by NIH Award No. NS 13274.]

Voice onset time in aphasia: Thai II. Production

The aim of this study was to investigate voice onset time (VOT) production in homorganic word-initial stops in Thai in order to explore the nature of speech production deficits across clinical varieties of aphasia. Thai exhibits a three-category distinction in bilabial (/b,p,p h/) and alveolar (/d,t,t, h/) stops, and a two-category distinction in velar (/k,k h/) stops. Subjects included three Broca asphasics, one transcortical motor asphasic, two global asphasics, one conduction aphasic, one Wernicke aphasic, one nonaphasic dysarthric patient, one right-brain-damaged patient, and five normal controls. Test stimuli consisted of eight monosyllabic real words. The results of VOT measurements indicated that Broca and global asphasics exhibited a more severe production disorder than Wernicke, conduction, or transcortical motor asphasics. The right-brain-damaged patient showed no impairment in VOT production. Comparisons are drawn to earlier studies of VOT production in aphasia in two-category languages. Issues concerning the underlying basis of the production deficit for nonfluent aphasics, fluent aphasics, and nonaphasic dysarthrics as well as the relation between perception and production of VOT are discussed.