In phonetics, a central vowel is a [[vowel sound]] produced with the tongue in a neutral or central position in the mouth. The most common central vowel sound is the schwa sound /ə/ which is often found in unstressed syllables in English words, such as 'sofa' and 'above'. Other central vowel sounds include the open-mid central vowel /ɜ/, as in 'bird', and the close central vowel /ɨ/, as in some dialects of Russian. Central vowels are characterized by their lack of distinct articulation, making them difficult to identify or differentiate from other vowels.