Children learn their phonological system of native language even since as young infant. They first year of an infant’s life which is before they can utter their first word are known as prelinguistic stage. Children do not utter their first word until they are about one year old. At one month, they show categorical perception of speech. A perceptual ability is ability to segment one sentence into individual word units. This ability usually leads to production and thus helps in the development of speech production. Even though children do not produce their first word until they approximately 12 month years old, the ability to produce speech sound start to develop at a much younger age. After the mother giving birth, the young infant will produce undifferentiated birth cry. Within 0 to 6 weeks, the infant can produce reflexive sound which are glottal catch and vowels such as ah, eh, and uh. Plus the infant also can produce some variety non-crying sound. They also produce differentiated cry which that true vocal communication begins. In the range 6 to 16 weeks, infant start to produce cooing sound when they are happy. Moreover, they begin to produce single syllables and blowing bubbles.
At 4 month, infant still prefer infant-directed compare to adult-director speech. Plus by 4 month, infant have learned which feature they have to pay attention to at the suprasegmental level such as intonation and stress. At 5 months old, infant prefer to hear their own name to similar sounding word. On the other