Biomedical subjects

Ray D Kent

Publications and source records attributed to Ray D Kent.

9 recordsLinked to original sources

PubMed2006

Evidence-based practice in communication disorders: progress not perfection.

PURPOSE: This commentary is written in response to a companion paper by Nan Bernstein Ratner (Evidence-Based Practice: An Examination of its Ramifications for the Practice of Speech-Language Pathology). METHOD: The comments reflect my experience as Vice President for Research and Technology of the American Speech-Language-Hearing Association (ASHA). One of the responsibilities of the Vice President is to monitor the work of the Advisory Committee on Evidence-Based Practice. CONCLUSION: Evidence-based practice (EBP) is a challenging but attainable goal for audiology and speech-language pathology. Our professions have made rapid progress in developing the foundations for EBP. To be sure, a great deal of work remains to be done, but we have learned from the experiences of other professions and have built our own systems to support EBP.

Communication Disorders↗

PubMed2005

Breath-group intelligibility in dysarthria: characteristics and underlying correlates.

PURPOSE: This study was designed to determine whether within-speaker fluctuations in speech intelligibility occurred among speakers with dysarthria who produced a reading passage, and, if they did, whether selected linguistic and acoustic variables predicted the variations in speech intelligibility. METHOD: Participants with dysarthria included a total of 10 persons with Parkinson's disease and amyotrophic lateral sclerosis; a control group of 10 neurologically normal speakers was also studied. Each participant read a passage that was subsequently separated into consecutive breath groups for estimates of individual breath group intelligibility. Sixty listeners participated in 2 perceptual experiments, generating intelligibility scores across speakers and for each breath group produced by speakers with dysarthria. RESULTS: Individual participants with dysarthria had fluctuations in intelligibility across breath groups. Breath groups of participants with dysarthria had fewer average words and reduced interquartile ranges for the 2nd formant, the latter a global measure of articulatory mobility. Regression analyses with intelligibility measures as the criterion variable and linguistic and acoustic measures as predictor variables produced significant functions both within and across speakers, but the solutions were not the same. CONCLUSIONS: Linguistic or acoustic variables that predict across-speaker variations in speech intelligibility may not function in the same way when within-speaker variations in intelligibility are considered.

Adult↗

PubMed2005

Development of vocal tract length during early childhood: a magnetic resonance imaging study.

Speech development in children is predicated partly on the growth and anatomic restructuring of the vocal tract. This study examines the growth pattern of the various hard and soft tissue vocal tract structures as visualized by magnetic resonance imaging (MRI), and assesses their relational growth with vocal tract length (VTL). Measurements on lip thickness, hard- and soft-palate length, tongue length, naso-oro-pharyngeal length, mandibular length and depth, and distance of the hyoid bone and larynx from the posterior nasal spine were used from 63 pediatric cases (ages birth to 6 years and 9 months) and 12 adults. Results indicate (a) ongoing growth of all oral and pharyngeal vocal tract structures with no sexual dimorphism, and a period of accelerated growth between birth and 18 months; (b) vocal tract structure's region (oral/anterior versus pharyngeal/posterior) and orientation (horizontal versus vertical) determine its growth pattern; and (c) the relational growth of the different structures with VTL changes with development-while the increase in VTL throughout development is predominantly due to growth of pharyngeal/posterior structures, VTL is also substantially affected by the growth of oral/anterior structures during the first 18 months of life. Findings provide normative data that can be used for modeling the development of the vocal tract.

Age Factors↗

PubMed2003

Toward an acoustic typology of motor speech disorders.

Acoustic methods have progressed to the point that an acoustic typology of the motor speech disorders can be constructed from a parameteric assessment of the speech subsystems (e.g., phonation, nasal resonance, vowel articulation, consonant articulation, intonation, and rhythm). The results of this analysis can be interpreted in respect to global functions in speech (e.g., voice quality, intelligibility, and prosody). This paper reviews studies showing that specific acoustic analyses have demonstrated or potential value toward the overall goal of constructing acoustic profiles of dysarthria and apraxia of speech. Several different acoustic measures are relevant to the study of the motor speech disorders, and these are increasingly supported by normative data and by guidelines for clinical application. Examples of these applications are discussed for a variety of specific neurologic diseases or perceptual types of disorder. Acoustic studies are useful in the study of motor speech disorders and recent progress points to a parametric analysis.

Humans↗

PubMedDate not supplied

Dysarthria associated with traumatic brain injury: speaking rate and emphatic stress.

UNLABELLED: Prosodic abnormality is common in the dysarthria associated with traumatic brain injury (TBI), and adjustments of speaking rate and emphatic stress are often used as steps in treating the speech disorder in patients with TBI-induced dysarthria. However, studies to date do not present a clear and detailed picture of how speaking rate and emphatic stress are affected in this speech disorder. This study, based on the acoustic analyses of syllable repetitions and sentence speech samples, reports on speaking rate and emphatic stress for 12 subjects with TBI and 8 healthy controls. For speaking rate, the subjects with TBI had (1) both slow speaking and articulation rates, (2) smaller phonation proportion and larger pause proportion, and (3) larger percentage change in speaking rate and smaller percentage change in articulation rate. For emphatic stress, the subjects with TBI had (1) significant increases in the difference and percentage change between pre-stressed and pre-unstressed pause durations, (2) significantly smaller difference between stressed and unstressed word durations, but not the percentage change between stressed and unstressed word durations, and (3) significantly reduced differences in f(0) movement and f(0) slope between stressed and unstressed words, but not in RMS range. This study demonstrates the multidimensional nature of prosodic deficits in the dysarthria related to TBI and illustrates the ability of acoustic measures to give a picture of the dysprosody related to TBI-induced dysarthria. LEARNING OUTCOMES: As a result of this activity, the participant will be able to (1) describe the prosodic disturbances that have been reported in studies of dysarthria associated with TBI; (2) define acoustic measures appropriate to the analysis of changes in speaking rate and emphatic stress; and (3) discuss the importance of prosody to spoken communication.

Adolescent↗

PubMedDate not supplied

Alternating motion rate as an index of speech motor disorder in traumatic brain injury.

The task of syllable alternating motion rate (AMR) (also called diadochokinesis) is suitable for examining speech disorders of varying degrees of severity and in individuals with varying levels of linguistic and cognitive ability. However, very limited information on this task has been published for subjects with traumatic brain injury (TBI). This study is a quantitative and qualitative acoustic analysis of AMR in seven subjects with TBI. The primary goal was to use acoustic analyses to assess speech motor control disturbances for the group as a whole and for individual patients. Quantitative analyses included measures of syllable rate, syllable and intersyllable gap durations, energy maxima, and voice onset time (VOT). Qualitative analyses included classification of features evident in spectrograms and waveforms to provide a more detailed description. The TBI group had (1) a slowed syllable rate due mostly to lengthened syllables and, to a lesser degree, lengthened intersyllable gaps, (2) highly correlated syllable rates between AMR and conversation, (3) temporal and energy maxima irregularities within repetition sequences, (4) normal median VOT values but with large variation, and (5) a number of speech production abnormalities revealed by qualitative analysis, including explosive speech quality, breathy voice quality, phonatory instability, multiple or missing stop bursts, continuous voicing, and spirantization. The relationships between these findings and TBI speakers' neurological status and dysarthria types are also discussed. It was concluded that acoustic analyses of the AMR task provides specific information on motor speech limitations in individuals with TBI.

Adolescent↗

PubMedDate not supplied

Production and perception of mandarin tone in adults with cerebral palsy.

The primary objective of the present study was to document tone production and intelligibility deficits in Mandarin-speaking persons with cerebral palsy (CP). Spastic, athetoid, and mixed types of CP were studied, along with a control group, to investigate the possibility of tone production and intelligibility deficits that were differentially affected by type of CP. Speakers produced a 78-word list that included contrasts for all four Mandarin tones. Intelligibility data were obtained for these words from 26 native speakers of Mandarin, and F0 contour analyses were implemented in CSpeech (Milenkovic) for a subset of the words. Mean tone intelligibility for speakers with CP was 73%, significantly different from the 91% value for control speakers. F0 contour analysis showed that speakers with CP maintained some contrast among the F0 contours for the four tones, but with less distinction than contrasts observed for control speakers. Discussion focuses on the role of tone in a model of the dysarthria associated with CP.

Adolescent↗

PubMedDate not supplied

The uniqueness of speech among motor systems.

This paper considers evidence that the speech muscles are unique in their genetic, developmental, functional and phenotypical properties. The literature was reviewed using PubMed, ScienceDirect, ComDisDome and other literature-retrieval systems to identify studies reporting on the craniofacial and laryngeal muscles. Particular emphasis was given to studies of muscle fibre composition. A number of studies on mandibular, lingual, palatal and laryngeal muscles in humans show that these muscles are distinct from limb and other muscles. These speech-related muscles typically contain diverse fibre types and these types can vary regionally within a muscle. In general, the muscles of the speech production system are designed for fast and/or variable contraction and fatigue resistance. The craniofacial and laryngeal muscles are unique among the muscle systems of the human body and the specialized properties of these muscles are relevant to understanding the biomechanics of speech and various speech disorders.

Facial Muscles↗

PubMedDate not supplied

Dysarthria in traumatic brain injury: a breath group and intonational analysis.

Prosodic abnormality is a common feature in the dysarthrias associated with traumatic brain injury (TBI), but very few analytic studies have been reported on the nature of the prosodic disturbances. This study, based on analyses of conversational and sentence speech samples, reports on breath group structure and its temporal and intonational components for 12 subjects with TBI and 8 healthy controls. It introduces the method of f0 close-copy stylization to the study of intonational patterns in dysarthria. The subjects with TBI had reduced mean length and variation of breath groups along with frequent inappropriate locations of breath pause and lengthy and variable breath pauses. Prosodic features that were preserved in the subjects with TBI were phrase final lengthening, f0 downtrend and a relatively normal f0 distribution. However, these subjects had reduced speaking and articulation rates, reduced f0 movement and reduced f0 slope. The phrase final lengthening and f0 downtrend phenomena, which can serve as prosodic cues of syntactic boundary, appear to be robust features of speech production, but the dynamic features of f0 control were more vulnerable to the neurological damage. This study indicates the importance of breath group management in TBI-induced dysarthria and the need to use methods such as those used in this study for large-scale investigations that examine cognitive, linguistic and motoric factors that conspire to reduce communicative efficiency.

Adult↗