Processes of speech perception and speech production will be examined in normal children, and in four well-defined groups of language-impaired (LI) children. The LI groups will be made up of carefully documented cases of: a) phonologic-syntactic dysphasia or specific language impairment; b) verbal dyspraxia; c) verbal agnosia; d) hyperlinguistic language disorder. There will be 10 to 20 children in each of the impaired groups and 80 normal subjects. Forty of the normals will be control subjects on the major project proposed. An additional 40 normal subjects will be studied in preliminary work in which phonetic contrasts and response formats will be ranked in difficulty. Tests of speech perception will vary in the Response Format required, and in the level of anticipated difficulty of specific phonetic contrasts presented. Interest will focus: a) upon whether there is evidence of a primary auditory deficit as opposed to a perceptual learning disorder in any of the LI groups, and b) upon the relationship between syllable perception and sentence processing in an 'on line' interactive task. Tests of speech production will include items addressing primary oral/speech motor abilities, as well as tasks assessing speech motor learning; labelling of the stimuli from the speech perception experiment; naming; nonsense syllable repetition; and speech shadowing.
The aims will be to find out: a) whether there is evidence of a primary oral/speech motor deficit as apposed to a speech motor learning impairment in any of the LI subgroups, b) if speech perception and production skills are as well integrated in LI as in normal children, and, c) to what extent speech production abilities may be related to sentence processing and to sentence production in the LI as well as in the normal children. These studies will help the investigators to generate hypotheses about language impairments and the possible cerebral localization of language malfunctions in LI children. These hypotheses will be tested in later brain imaging and electrophysiologic studies of LI children.
