The purpose of this study was to examine changes in prelinguistic vocal production pattern during the first 18 months of life. Normal hearing ten Korean infants whose age range were 1 to 18 months and one cochlear implanted child whose age was 30 months participated with the parents' agreements. Data were recorded and collected with camcorder then analyzed utilizing the Stark Assessment of Early Vocal Development-Revised (SAEVD-R). The results showed that early vocal development of 1~18 months infants with normal hearing produced higher level of SAEVD-R such as vowels, consonants, and monosyllables as the age increased. Also, central vowel /a/ was firstly produced and the process of vowel development was moved from the front vowels to the back vowels. When the consonant production was classified according to place of articulation, the production started with bilabial and developed labiodental and velar later. When the consonant production was classified according to manner of articulation, plosives, and nasals were produced mostly. For the cochlear implanted child, the vowel /a/ was produced most frequently and /ɨ/, /i/, and /e/ were produced in the order. Conclusively, this study analysed normal Korean infants' vocal development according to the SAEVD-R and presented the lists and steps to follow for the hearing impaired infants' aural rehabilitation of 1 to 18 months of age. Further, more normal and hearing impaired infants' data should be included for more systematic plans of aural rehabilitation of that age. Also, more data of the cochlear implanted children should be included for completed understanding and comparison of vocal developments of the normal and hearing impaired infants