All information on the Osage vowel and consonantal systems stems from Quintero's Osage Grammar (Quintero 2004: 16-42).

The Osage vowel system

front central back
unrounded rounded nasal unrounded rounded unrounded rounded nasal
high i (u) ĩ u (ü [y])
mid e o õ
low a ã
  • u is high front rounded or high central rounded, in the latter case ü [y]
  • there is high variation in the use of ã and õ; they are often interchangeable. My interpretation, which is consistent with at least Omaha-Ponca, a Degiha language too, is that the actual nasal sound is rather a nasal ɔ [ɔ̃], which is a vowel approximately between ã and õ. The transcription then, if one doesn't employ the IPA symbol ɔ̃, must choose between ã and õ.

The Osage consonantal system

Quintero considers underlying segments ph, th and kh which according to her never emerge on the surface; they are in parenthesis in the table.

Labial Dental Palato-
alveolar
Velar Glottal
Stops Glottalized pʔ cʔ   kʔ
Lax p t č k
Preaspirated hp ht  hč hk  
Aspirated (ph) (th)
ch
(kh)  
Voiced b        
Fricatives Voiceless    s š x h
Voiced    z  ž ɣ  
Nasals m n      
Approximants n l
ð
r
     
  • The voicing of z and ž is faint.
  • The approximant r only occurs in the cluster br. In 1SG marked verbs, br occurs frequently, where in Quintero's interpretation r is an allophone of ð. There are also other occurrences of br, which Quintero calls "morphologically opaque"; e.g. brã  'smell, emanate an odour', íbrã  'have/get enough of', bráaska  'flat'.