Pronunciation of English r has many variations in different dialects.
Contents
Variations of "r"
R-labialization
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.
R-labialization leads to pronunciations such as the following:
However, replacement of /r/ by some kind of labial approximant may also occur as symptom of a speech defect, called rhotacism or, more precisely, derhotacization.
R-tapping
R-tapping refers to pronouncing the "r" as a flap intervocalically. This occurs in for many Scottish English speakers.
R-rolling
R-rolling refers to pronouncing the "r" as a trill. This occurs in for some Scottish English speakers.
Rhotic and nonrhotic
Rhotic dialects pronounce /r/ in words like "car" and "cord" whereas nonrhotic ones don't.
Vowel mergers before r
Many dialects have merged certain vowels occurring before historic /r/. For instance, most North Americans merge "Mary", "marry" and "merry".