The open-mid central unrounded vowel, or low-mid central unrounded vowel, is a type of vowel sound, used in some spokenlanguages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɜ⟩. Note that the IPA symbol is not the digit ⟨3⟩, but a reversed Latinized variant of the lowercase epsilon, ɛ. The value of this letter was only specified in 1993; before that, it was transcribed ⟨ɛ̈⟩.
The IPA prefers terms "close" and "open" for vowels, and the name of the article follows this. However, a large number of linguists, perhaps a majority, prefer the terms "high" and "low". It has also been described as a 'long schwa', after the extremely common short vowel it resembles a slightly longer form of.
Sulcalized (the tongue is grooved like in [ɹ]). 'Upper Crust RP' speakers pronounce a more open vowel [ɐː], but for most other speakers it's actually mid ([ɜ̝ː]). This vowel corresponds to rhotacized[ɝ] in rhotic dialects.
Roach, Peter (2004), British English: Received Pronunciation, Journal of the International Phonetic Association34 (2): 239–245, doi:10.1017/S0025100304001768
Thomas, Erik R. (2001), An acoustic analysis of vowel variation in New World English, Publication of the American Dialect Society 85, Duke University Press for the American Dialect Society, ISSN0002-8207
Wells, John C. (1982), Accents of English, 2: The British Isles, Cambridge: Cambridge University Press.