The Amstetten dialect is very unusual among the world's language varieties in that it can be analyzed as featuring five phonemic vowel heights. Phonetically speaking, the vowels typically transcribed with ⟨æ,ɶ,ɒ⟩ in IPA constitute a series of open-mid vowels ([ɛ,œ,ɔ] in narrow transcription), one-third the distance between the open central /a/ and the close /i,y,u/ in the formant vowel space. The vowels transcribed with ⟨ɛ,œ,ɔ⟩ and ⟨e,ø,o⟩ also differ from the cardinal vowels; the first series is close-mid ([e,ø,o] in narrow transcription), two-thirds the distance between /a/ and /i,y,u/. The remaining /e,ø,o/ are near-close ([e̝,ø̝,o̝] or [ɪ̟,ʏ̟,ʊ̠] in narrow transcription), a series of very high vowels that approach /i,y,u/ in their articulation. Among those, the back [o̝] is somewhat more central [ö̝] than the neighboring [u] and [o].[1]
This rich vowel system is also found in most other dialects of Lower Austria. The open series ⟨æ,ɶ,ɒ⟩ has historically developed from earlier diphthongs ⟨aɛ,ɒœ,aɔ⟩ that are still preserved in Upper Austrian dialects (e.g. Lower Austrian /dætn/ vs. Upper Austrian /daɛtn/ 'to point'). The dialect of Vienna shares with Lower Austrian dialects the monophthongization of these diphthongs, but has conflated the ⟨ɛ,œ,ɔ⟩ and ⟨e,ø,o⟩ series and thus only distinguishes four vowel heights.[1]
