Bearing the importance of perception in the acquisition of a second language and the different factors that may affect an accurate identification of nonnative sounds, the main objective of this study was to investigate perception of the English word-final /m-n/ by Brazilian learners. This contrast has different patterns of phonetic realizations across languages, whereas they are distinctively pronounced in English, in Brazilian Portuguese they are not fully realized. Taking this phonetic difference into consideration, this study mainly aimed at investigating whether Brazilian learners of English were able to identify the native-like realization of those nasals; and verifying whether visual cues favored the identification of the target consonants.Two perception tests were designed and taken by a group of Americans, as a reference for comparison, and by a group of Brazilians. The book reports and discusses the perception tests designed for data collection as well as the results andits theoretical and pedagogical implications. Studies in interlanguage phonetics and phonology can provide a testing ground for phonological, phonetic and second language acquisition theories.