Molar-r

Pronunciation of English r has many variations in different dialects.

R-labialization is a process occurring in certain dialects of the English language, particularly some varieties of Cockney, in which the /r/ phoneme is realized as a labiodental approximant [ʋ] in contrast to an alveolar approximant [ɹ]. To English speakers who are not used to [ʋ], this sounds nearly indistinguishable from /w/.

Use of labiodental /r/ is commonly stigmatized by prescriptivists. Regardless, the consonant [ʋ] is used in a variety of other languages and is increasing in many accents of British English. Most speakers doing so are from the southeastern part of the country, particularly in London. It is also occasionally heard in some speakers of Boston accent though more often in an exaggerated parody of these dialects, as famously portrayed by the Looney Tunes character Elmer Fudd.

It has also been reported to be an extremely rare realization of /r/ in New Zealand English.

The /r/ realization may not always be labiodental: bilabial and velarized labiodental realizations have been reported.

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