Modern Quazian has a ten-vowel system split into front (/i e æ y ø/) and back (/ɯ ɤ ɑ u o/) vowels. A single word can switch vowel classes as part of its inflectional routine, like so:
ŋakka "word (nom.)"
ŋäkkää "word (acc.)"
where Classical Quazian had ŋak'a and ŋak'a ja; later the accusative clitic ja merged with the preceding word and the -j- deleted, turning the preceding vowel into a front vowel. Since the penult was stressed, this affected the entire word. Similarly:
väʻi "hand (nom.)"
vaʻuu "hand (instr.)"
The Classical Quazian instrumental clitic hu became a case-ending; when -h- dropped out after a penultimate vowel, it backened the entire word, if front.