Objective
The purpose of this study is to determine clinical and phonological characteristics of the patients with specific language impairment (SLI).

Method
Subjects were 24 SLI patients without known mental retardation, cerebral palsy, epilepsy, hearing loss or structural brain lesion and 23 normal children. Developmental history, oropharyngeal abnormality, and brainstem auditory evoked potentials were obtained in SLI patients. Receptive language age and quotient were assessed by Peabody picture vocabulary test. Phonetic characteristics of subjects were analysed using Visi-Pitch^Ⱂ and computerized speech laboratory.

Results
In perceptual evaluation, 32.3% of SLI patients showed incomplete articulation pattern. The patterns of incomplete articulation were substitution, distortion, nasalization, and addition. The receptive language of SLI patients (0.89⁑0.28) was significantly lower than control group (1.16⁑0.18). In Visi-Pitch^Ⱂ analysis, diadochokinetic rate and maximal phonation time were decreased in SLI patients. The total duration of three syllables in SLI patients were significantly prolonged, especially for bilabial heavily asperated and glottalized consonants and alveolar and velar slightly asperated, heavily asperated, and glottalized consonants.

Conclusion
The patients with SLI showed characteristic defect in articulation as well as expressive and receptive language delayment. This articulatory defect may be resulted from disturbance of central programming and coordination of articulation. The objective and quantitative analysis of Phonological characteristics using computerized speech system in SLI patients can contribute to diagnose and evaluate the treatment outcome for the patients.