There are some audio files here. http://www.uiowa.edu/~acadtech/phonetics/english/frameset.html

So a good way to learn these also is to look at an english phonology chart to help you learn the vowel sounds. The chart shows you the roundness of your mouth and position of your tongue as you say vowels. Look up some of those words in the dictionary and then look at the chart. There are some audio files here. http://www.uiowa.edu/~acadtech/phonetics/english/frameset.html

U - stressed closed syllable: - u = [ A ] e.g. up ugly cup gun lunch must butter number but Exception: u = [ U ] e.g. butcher pudding put ruth truth

Welcome to the wonderful world of English pronunciation. Not everything makes sense. However, "put" is the only word pronounced differently in there letter combinations with "-ut". But, cut, gut, hut, jut, mutt, nut, PUTT, rut, tut are all pronounced the same. Only put is different. Also, putter and putted (golf terms) are pronounced the same as butter, cutter, etc. So just remember that "put" is the only exception.