What are most common differences between rhetoric,spoken and slurry pronunciation in different english language varieties (USA,UK&Australian)?
It is difficult to recognize changed words in real fast speech for non-native english learners. What are the most useful pronunciation study tips?
All languages "slur" pronunciation in connected speech. English is not alone in this respect, nor is English any more or less slurred than average. The changes are not necessarily indications of substandard speech. Most are consequences of articulatory economy—every language has sound combinations that are difficult to say rapidly, and often these change in rapid, connected speech.
Studying phonetic transcription of connected speech can be extremely useful for understanding and producing correct pronunciation. Just listening is fine, but phonetic transcription is to language as musical notation is to music. Sometimes hearing is fine, but at other times you really need to see hardcopy documentation of the sounds.