In this paper we describe similarities and differences in the formant trajectories of Australian English diphthongs /OX/, /ai/ and /IB/ in "boy", "buy" and "here" in two dialects, one spoken by native speakers of Australian English and another spoken by Tamil migrants living in Australia. This contrastive analysis conducted in f1-f2 plane lend support to the view ([5],[6]) that non-native speakers tend to approach native speaker's certain sound with longer exposure to the target dialect.