Biomedical subjects

H K Vorperian

Publications and source records attributed to H K Vorperian.

7 recordsLinked to original sources

PubMed2000

An auditory-feedback-based neural network model of speech production that is robust to developmental changes in the size and shape of the articulatory system.

The purpose of this article is to demonstrate that self-produced auditory feedback is sufficient to train a mapping between auditory target space and articulator space under conditions in which the structures of speech production are undergoing considerable developmental restructuring. One challenge for competing theories that propose invariant constriction targets is that it is unclear what teaching signal could specify constriction location and degree so that a mapping between constriction target space and articulator space can be learned. It is predicted that a model trained by auditory feedback will accomplish speech goals, in auditory target space, by continuously learning to use different articulator configurations to adapt to the changing acoustic properties of the vocal tract during development. The Maeda articulatory synthesis part of the DIVA neural network model (Guenther et al., 1998) was modified to reflect the development of the vocal tract by using measurements taken from MR images of children. After training, the model was able to maintain the 11 English vowel targets in auditory planning space, utilizing varying articulator configurations, despite morphological changes that occur during development. The vocal-tract constriction pattern (derived from the vocal-tract area function) as well as the formant values varied during the course of development in correspondence with morphological changes in the structures involved with speech production. Despite changes in the acoustical properties of the vocal tract that occur during the course of development, the model was able to demonstrate motor-equivalent speech production under lip-restriction conditions. The model accomplished this in a self-organizing manner even though there was no prior experience with lip restriction during training.

Child Development↗

PubMed1999

Magnetic resonance imaging procedures to study the concurrent anatomic development of vocal tract structures: preliminary results.

The vocal tract structures undergo drastic anatomic restructuring during the course of development from infancy to adulthood. This study demonstrates the feasibility of using MRI to examine the growth processes of the vocal tract. This method affords precise and detailed visualization of the soft tissues in the oro-pharyngeal region, while also providing images of related bony and cartilaginous structures. Information on anatomic restructuring contributes to the understanding of how speech emerges and develops, and it also establishes normative information that can be used in the assessment of developmental anomalies. This paper describes the method used to measure and examine the concurrent anatomic development of the various vocal tract structures during early childhood. Preliminary results from two pediatric subjects indicate that there is synchrony of growth in the different structures-both soft and hard tissues-, and that such synchronous growth appears to persist during periods of growth spurts.

Child, Preschool↗

PubMed1997

A speaking task analysis of the dysarthria in cerebellar disease.

Cerebellar disease affects a number of skilled movements, including those in speech. Ataxic dysarthria, the speech disorder that typically accompanies cerebellar disease, was studied by acoustic methods. Control subjects and subjects with ataxic dysarthria were recorded while performing a number of speaking tasks, including sustained vowel phonation, syllable repetition, monosyllabic word production (intelligibility test), sentence recitation, and conversation. Acoustic data derived from the speech samples confirmed the hypothesis that temporal dysregulation is a primary component of the speech disorder. The data also show that the nature of the disorder varies with the speaking task. This result agrees with observations on other motor systems in subjects with cerebellar disease and may be evidence of a dissociation of impairments. Suggestions are offered on the selection of measures for a given task and on the role of the cerebellum in the regulation of speaking.

Adult↗

PubMed1995

A developmental study of the perception of onset spectra for stop consonants in different vowel environments.

The importance of different acoustic properties for the perception of place of articulation in prevocalic stop consonants was investigated from a developmental perspective. Eight adults and eight children in each of the age groups, 5, 6, 7, 9, and 11 years, listened to synthesized syllables comprised of all combinations of [b d g] and [i a]. The synthesis parameters were adapted from Blumstein and Stevens [J. Acoust. Soc. Am. 67, 648-662 (1980)], and included manipulations of the following stimulus variables: formant transitions (moving or straight), noise burst (present or absent), and voicing duration (10 or 46 ms). Identification performance was high for all age groups across most stimulus types. Formant transition motion generally was not necessary for accurate identification, and there was no difference between age groups in terms of the perceptual weight placed on this cue. Furthermore, the results did not support the salience of duration as a developmental cue to place of articulation. The presence of a burst improved identification for the velar and alveolar places of articulation for all age groups, but was particularly important for the 11-year-olds and adults. These findings indicate that children, by age 5, do not rely on dynamic formant motion any more than adults do, and that the ability to integrate acoustic cues across regions of spectral change shows developmental patterns.

Adult↗

PubMed1995

Stimulus intensity and fundamental frequency effects on duplex perception.

Duplex perception occurs when part of the acoustic signal is used for both a speech and a nonspeech percept. This phenomenon has been interpreted as evidence of a distinct system for speech perception that precedes other specialized systems of general auditory processing (such as auditory grouping, and perception of pitch, loudness, and timbre). This interpretation was investigated by using an intensity-dependent form of duplex perception with the acoustic pair /da/ and /ga/. The "base" portion of the stimulus, common to both, consisted of the first and second formants and the steady-state portion of the third formant (F3). The F3 transition (either a sinusoid or a true formant), which cued the difference between /da/ and /ga/, was varied in intensity and fundamental frequency (F0). For every subject, the level at which each type of F3 transition was barely audible in the context of the base, i.e., duplex perception threshold, was first established. Next, identification functions were obtained by varying the intensity of the F3 transition relative to each subject's duplex perception threshold. Results revealed that duplex perception thresholds decreased as the F0 of the F3 transition increasingly differed from the base. Also, identification functions showed that, as has been previously demonstrated, the F3 transition contributed to the speech percept over a wide range of intensities and fundamental frequencies. However, as F3 transition intensity increased well above duplex perception threshold, /ga/ identification decreased. Also, both /da/ and /ga/ identification progressively decreased as the F0 of the F3 transition increasingly differed from the base. Contrary to previous duplex perception reports, such findings indicate that both intensity and F0 information is available to the specialized speech perception system. Thus, the computations of the speech perception system and its relation to the general auditory processing systems need to be reexamined.

Adult↗

PubMedDate not supplied

Voice dysfunction in dysarthria: application of the Multi-Dimensional Voice Program.

Phonatory dysfunction is a frequent component of dysarthria and often is a primary feature noted in clinical assessment. But the vocal impairment can be difficult to assess because (a). the analysis of voice disorder of any kind can be challenging, and (b). the voice disorder in dysarthria often occurs along with other impairments affecting articulation, resonance, and respiration. A promising assessment tool is multi-parameter acoustic analysis, such as the Multi-Dimensional Voice Program (MDVP). Part 1 of this paper recommends procedures and standards for the acoustic analysis of voice, including (1). selection of the sample to be analyzed, (2). signal quality requirements, (3). availability of normative data for both genders and different ages of speakers, (4). reliability of analysis, and (5). correlation of acoustic results with results from other methods of analysis. In Part 2, acoustic data are reviewed for the dysarthria associated with Parkinson disease (PD), cerebellar disease, amyotrophic lateral sclerosis (ALS), traumatic brain injury (TBI), unilateral hemispheric stroke, and essential tremor. Tentative profiles of voice disorder are described for these conditions. These profiles may serve as hypotheses for future research. Although several issues remain to be resolved in the acoustic analysis of voice disorder in dysarthria, steps can be taken now to promote the reliability, validity, and clinical utility of such analyses. (1). As a result of this activity, the participant will be able to describe ways in which an optimal multi-dimensional analysis of voice can be performed with modern acoustic analysis systems. (2). As a result of this activity, the participant will be able to apply multi-dimensional acoustic analysis of voice to individuals who have a dysarthria-related voice disorder. (3). As a result of this activity, the participant will be able to identify major sources of normative data on the Multi-Dimensional Voice Program.

Amyotrophic Lateral Sclerosis↗

PubMedDate not supplied

Acoustic studies of dysarthric speech: methods, progress, and potential.

EDUCATIONAL OBJECTIVES: (1) The reader will be able to describe the major types of acoustic analysis available for the study of speech, (2) specify the components needed for a modern speech analysis laboratory, including equipment for recording and analysis, and (3) list possible measurements for various aspects of phonation, articulation and resonance, as they might be manifest in neurologically disordered speech.

Dysarthria↗