Jackson T. Gandour, Ph.D. - US grants

The specific aims of this research are to study the production and perception of important linguistic patterns in the speech of laryngectomized patients who are native speakers of a tone language. Highly-rated alaryngeal speakers of Thai, including two conventional esophageal speakers and one user of the Servox electrolarynx, are chosen for investigation. Proposed studies focus on four linguistic patterns in Thai: tone, word-initial stops, vowel length, and rhythm. Taken together, acoustical and perceptual investigations of these linguistic aspects of speech after laryngectomy should contribute new and useful information concerning both phonatory and nonphonatory aspects of alaryngeal speech production. With these contributions to our body of knowledge about alaryngeal speech, we move a step closer to our long-term objectives which are to delineate aerodynamic and physiologic mechanisms underlying alaryngeal speech production and to develop both diagnostic and remedial speech rehabilitation programs for patients with cancer of the larynx.

Our primary objectives are to produce new data on tone in aphasia and, at the same time, address theoretical issues concerning hemispheric specialization for tone and the nature of dysprosody in Broca's aphasia. Two experimental phonetic investigations are proposed. The purpose of the first study is to determine the extent and nature of impairment in the production of tones by Thai-speaking aphasics. Thirteen subjects will provide the data for this study including 5 normal and 8 brain-damaged (2 Broca's, 1 transcortical motor, 1 global, 1 conduction, 1 Wernicke's, 1 dysarthric, and 1 right brain-damaged) native speakers of Thai. The purpose of the second study is to determine the extent to which the control of FO and timing may be selectively impaired depending upon the size of the linguistic planning unit in the speech of a single Thai-speaking Broca's aphasic. Both studies will employ computerized techniques of acoustical analysis of FO and timing. The long-term objectives of this research program are (1) to provide a detailed, aoustical description of FO and timing patterns in spontaneous and read speech of Thai-speaking aphasics, as well as other brain-damaged populations, and (2) to show how both normal and abnormal FO and timing patterns can give insight into the nature of language deficits that follow from damage to the brain. The studies represent a first step toward the attainment of these long term goals. Such detailed descriptions of the breakdown of prosodic elements in aphasia are essential for accurate clinical assessment and remediation of dysprosody in aphasic patients.

The primary objectives of this research are to produce new data on prosodic aspects of speech after brain damage in patients who are native speakers of a tone language and, at the same time, address theoretical issues concerning the extent and nature of prosodic deficits in patients with unilateral left hemisphere lesions and patients with unilateral right hemisphere lesions. The language selected for investigation is Thai, the national language of Thailand. A series of experimental phonetic investigations of fundamental frequency and timing in Thai are proposed to contribute original data that not only bear on specific theoretical issues concerning the underlying structure and processing of language in the human brain, but also serve to fill a conspicuous gap in acoustic phonetic information about fundamental frequency and timing beyond monosyllabic citation forms in normal speech. As a whole, this series of experiments is designed to show (1) that some elements of prosody may be impaired while others are spared following damage to the human brain; (2) that the size of the temporal domain over which prosodic features are manifested is the critical variable that determines their susceptibility to disruption; and (3) that speech produced by patients with right hemisphere lesions is dysprosodic in emotional contexts only. The longer term objectives of this research program are (1) to provide a detailed, acoustical description of Fo and timing patterns in spontaneous and read speech of Thai-speaking patients with unilateral left and right hemisphere lesions, as well as other brain-damaged patients with subcortical lesions, (2) to provide information on the perception abilities of these brain -damaged patients with respect to linguistic contrasts in Thai mediated by Fo and timing, (3) to determine the relation between the production and perception abilities of these brain-damaged patients with respect to selected aspects of prosody in Thai, and (4) to show how both normal and abnormal Fo and timing patterns in a tone language can give insights into the nature of language deficits that follow form damage to the brain.

The long-term objective of this research is to develop a functional model of the neuroanatomy underlying the perception of speech prosody. The working hypothesis is that both hemispheres have attention-driven, task-dependent schemata for speech processing, and that those of the left hemisphere are responsible for linguistic information irrespective of acoustic cues, whereas those of the right hemisphere are prosody specific. To test this hypothesis, PET imaging techniques are employed to observe cerebral blood flow of the human brain in vivo while normal adult, Chinese-English bilinguals and English monolinguals perform perceptual judgments of natural and filtered Chinese and English speech stimuli. Specific aims are to identify neuroanatomical regions involved with the perceptual processing of various aspects of speech prosody at the word- and sentence-level in Chinese and English. Experiment 1 focuses on perceptual processing of word-level Chinese tones. Experiments 2-4 focus on perceptual processing of functionally equivalent, sentence-level aspects of linguistic and affective prosody in both Chinese and English. Chinese, a tone language, allows for the exploration of aspects of speech prosody ranging from the word level to the sentence level of English, a non-tone language, and to distinguish neural circuitry shared in common across languages from those directly attributable to language experience. Bilingual (Chinese-English) and monolingual (English) subjects and two sets of functionally-equivalent language stimuli (Chinese; English) allow for a comparison of neural circuitry underlying perceptual processing of speech prosody in bilingual and monolingual brains.

DESCRIPTION (provided by applicant): This application is for a continuing institutional grant designed to provide research training for 6 predoctoral and 3 postdoctoral trainees with research interests in communication disorders and sciences. Training prepares trainees to become active and responsible members of the scientific community. Hands-on apprenticeship training is provided in three interrelated areas: 1) Speech Production, Development, and Disorders: Lifespan Perspective (with special attention to sensorimotor processes in speech, and speech disorders from development through aging); 2) Language Structure, Development and Disorders: Single Language and Crosslinguistic Studies (including specific language impairment and American Sign language); and 3) Peripheral and Central Processing of Speech and Non-Speech Stimuli (with special reference to otoacoustic emissions and cochlear modeling). Trainees in these areas will be offered two "feeder" specialties: Cognitive Neuroscience (including imaging of normal and brain-damaged individuals) and Linguistics Applied to Communication Sciences and Disorders. Participating faculty routinely collaborate on projects that cut across these research areas. Advanced courses are available in communication disorders, research design, statistics, neurosciences, biology, engineering, and linguistics. However, the main purpose of the training program is to provide intensive interactive research experience leading toward establishment of successful independent clinical investigators.