The open front rounded vowel, or low front rounded vowel, is a type of vowel sound that has not been confirmed to be phonetic in any spoken language, but is occasionally used in phonemic transcriptions for some Germanic languages. The symbol in the International Phonetic Alphabet that represents this sound is , a small capital . It was added to the IPA vowel chart to balance the quadrilateral by filling in the remaining gap for a rounded equivalent of .
While the IPA chart lists this vowel as the rounded equivalent of , studies of formant acoustics suggest it is closer to the rounded equivalent of .
A phoneme transcribed by is reported for the Amstetten dialect of Bavarian; however, it is phonetically open-mid , pairing with unrounded phonemic (phonetic ). Similarly, certain transcriptions of Danish and Swedish use to transcribe a phoneme that is phonetically open-mid or near-open (depending on the analysis), where phonemic is phonetically raised closer to mid . In Maastrichtian Limburgish, the vowel transcribed with in the Mestreechter Taol dictionary is phonetically centralized, with a height between open-mid and near-open ; phonologically, it is the long counterpart of .
No language has been reported to have a phonetically true open realization. The table below provides examples of near-open realizations, which are phonetically raised compared to cardinal , and also often centralized (similar to , but not as central). In the case of the latter, these may be transcribed as mid-centralized (alternatively, or ).