amstetten austro-bavarian back vowel central vowel close-mid back rounded vowel close-mid front unrounded vowel close-mid vowel close back rounded vowel close front rounded vowel close front unrounded vowel close vowel formant front vowel international phonetic alphabet language mid central vowel near-back vowel near-close vowel near-front vowel near-open vowel open-mid vowel open front unrounded vowel open vowel roundedness schwa vowel