The open-mid back rounded vowel, or low-mid back rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɔ⟩. The IPA symbol is a turned letter c and both the symbol and the sound are commonly called "open-o". The name open-o represents the sound, in that it is like the sound represented by ⟨o⟩, the close-mid back rounded vowel, except it is more open. It also represents the symbol, which can be remembered as an o which has been "opened" by removing part of the closed circular shape.
In English, the symbol ⟨ɔ⟩ (or ⟨ɔː⟩) is typically associated with the vowel in "thought", but in Received Pronunciation ("RP", standard British English), Australian English, New Zealand English and South African English that vowel is produced with considerably stronger lip rounding and higher tongue position than that of cardinal [ɔ], i.e. as close-mid [oː] or somewhat lower. Open-mid [ɔː] or even open [ɒː] realizations are found in North American English (where this vowel is often indistinguishable from the open back unrounded vowel in "bra") and Scottish English as well as Hiberno-English, Northern England English and Welsh English, though in the last three accent groups closer, [oː]-like realizations are also found. In RP, the open-mid realization of /ɔː/ has been obsolete since the 1930s. Pronouncing that vowel as such is subject to correction for non-native speakers aiming at RP.
