Without the diaeresis (the dots) those three letters are said [a], [o], and [u]. In German, when the dots are put over them, Ä, Ö, and Ü change to sound like [ɛ], [œ]/[ø] and [y]/[ʏ].
w ɪ ð aʊ t WORD_BOUNDARY ð ə WORD_BOUNDARY d aɪ ə ə ɹ ɹ iː s ɪ s WORD_BOUNDARY ð ə WORD_BOUNDARY d ɑ t s WORD_BOUNDARY ð oʊ z WORD_BOUNDARY θ ɹ iː WORD_BOUNDARY l ɛ t ə ɹ z WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY s ɛ d WORD_BOUNDARY ʌ WORD_BOUNDARY oʊ WORD_BOUNDARY æ n d WORD_BOUNDARY j uː WORD_BOUNDARY ɪ n WORD_BOUNDARY d̠ʒ ɜː m ə n WORD_BOUNDARY w ɛ n WORD_BOUNDARY ð ə WORD_BOUNDARY d ɑ t s WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY p ʊ t WORD_BOUNDARY oʊ v ə ɹ WORD_BOUNDARY ð ɛ m WORD_BOUNDARY eɪ ʊ m l aʊ t WORD_BOUNDARY oʊ ʊ m l aʊ t WORD_BOUNDARY æ n d WORD_BOUNDARY j uː ʊ m l aʊ t WORD_BOUNDARY t̠ʃ eɪ n d̠ʒ WORD_BOUNDARY t ə WORD_BOUNDARY s aʊ n d WORD_BOUNDARY l aɪ k WORD_BOUNDARY oʊ p ə n ɛː WORD_BOUNDARY oʊ WORD_BOUNDARY s l æ ʃ WORD_BOUNDARY oʊ s t ɹ oʊ k WORD_BOUNDARY æ n d WORD_BOUNDARY w aɪ WORD_BOUNDARY s l æ ʃ WORD_BOUNDARY s m ɔ l k æ p w aɪ WORD_BOUNDARY