It is discussed that the research direction of phonetics has been different as that of cognitive studies in speech perception. A case of the cognitive studies is introduced to show the difference. The studies based on cross-linguistics showed clearly the effects of phonotactic constraint on speech perception. The effects observed are consonant deletion and vowel epenthesis, which occurs in prelexical level and is irrelevant to top down effect of lexical processing. Finally, the scope of the phonetics studies integrated with the studies of cognitive science are proposed to make a profound progress in future.
