Exposing students to a wide range of accents of both native and second language speakers is a recipe that must be cooked up for intermediate and advanced learners.
One great place for this would be The Speech Accent Archive . There you can choose mp3 samples from speakers all over the world. They all read the same paragraph so students can just concentrate on the “accent”. I’ve made a cool game from them.
Other recipes for doing this would be visiting Voicethread. There, students can encounter a wide range of authentic audio from speakers around the world. Here are some good examples. Also, The Language Accent Game is fun too.