Meryn Stol voted up this answer. Patrick Wallace Typically, when native speakers speak with non-native speakers, especially overseas, the native speakers speak much more slowly and clearly, using fewer idioms and much less slang. I find that this is true of myself--when I return to the US I find that my speech is much slower and easier to understand than most Americans. It is no doubt part of the legacy of living overseas for all these years. The speech you see in films is more like that in real life when compared to the speech of expatriates and language teachers, and the speech most often found on language-learning tapes. This is one reason why I suggest to my students that they watch English-language films and practice the on-screen dialogue by reading the subtitles using the same speed and intonation as the actors. Such a tactic will better prepare them to go to the US or Britain, by improving both their overall fluency and listening ability. See question on Quora - Meryn Stol