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After a certain age, a person’s sound references are totally connected to the native language. It is almost as if the native language acted as a filter for any foreign sound. If the sound is identical, there is no problem. If the sound is different, it is reinterpreted according to the native sound system. For example, a beginning student who hears the pronunciation of the TH in English will find no corresponding sound in the Brazilian Portuguese system. The student’s sound system will approximate the TH to whatever sounds closer to it in Portuguese. That would bring the TH closer to /s/, / f /, or /t/, thus resulting in “sink”, “fink” or “tink” instead of think. Likewise, some people might pronounce “day” instead of they. As a result, we could conclude that the native language affects not only the production of sounds but also the way a student hears them. For that reason, we believe that it is also important to focus on the listening skill when it comes to pronunciation. Learning pronunciation is learning to listen again! Production of the sounds comes almost as a by-product of good listening. Think about it: would we even speak our native language if we had not listened to it a lot?

(GODOY, Sonia, et al. English pronunciation for Brazilians: the sounds of American English. São Paulo: Disal, 2006, p.18).