americanist phonetic notation aspiration chinese language circumflex close-mid front rounded vowel cyrillic alphabet empty set epiglottal trill extensions to the ipa glottal stop gyeongsang dialect hangul history of the ipa international phonetic alphabet japanese language korean language naming conventions of the international phonetic alphabet nasal vowel near-close central rounded vowel near-close central unrounded vowel open back unrounded vowel oxford english dictionary phonology pinyin r-colored vowel sinology sokuon south korea tilde togo uralic phonetic alphabet