'Can't' which is the short form of 'cannot' is usually easier to hear because it is pronounced quite strongly (it is stressed) In British English the Pronounciation of the vowel is like the 'a' in car. In American English the pronounciation of the vowel is like 'a' in cat. Americans don't always pronounce the 't' so that can make it difficult to hear. 'Can' is sometimes stressed and sometimes unstressed. When stressed the vowel is like the 'a' in 'cat'. Can is usually stressed at the beginning of a question. Can you pass me the sugar?' Can is unstressed when it's in the middle of a sentence. Here you hardly hear the vowel at all, just the 'cn' or the vowel is very weak like the 'e' in 'the'. This sound is called a schwa, a very common sound in English (like the 'er' in 'teacher'.

Yes, the "t" in can't is very hard to hear in conversation. But also listen to the "a" in the middle of the word. can = "ken" (a = "uh") can't = "kant" (a = "ah") This video might help: http://www.youtube.com/watch?v=qwJAiCj-Rcs

If the words rock up in a song, then you can't hear the difference. For us it's obvious from the context. Secondly, we hear the silent "T" on the end of "can't". It takes a lot of practice to be able to hear that kind of stuff.

You could pronounce it as 牛肉面 described, which is a more American way of pronouncing them. As noted, it's difficult to hear the 't' sometimes. British pronunciation uses a more open "a" for "can", then changes and extends the vowel for "can't" (never pronounce it with a short vowel). This difference in the vowels makes it very clear which is the positive and which is the negative.

Kinda hard.