The effect of native language on the production of second-language speech segments was studied. It is hypothesized that difficulties in perceiving non-native speech segments is due to the interference of the phonological system of a listener's native language with their non-native perception. Various experiments were conducted on the perception of American english (AE) /r/ and /l/ by Japanese speakers and Korean speakers. It was found that production and perception might relate to each other at a syllabic position level.