English-language vowel changes before historic /r/

In non-rhotic dialects like Received Pronunciation (RP), historic /r/ is elided at the end of a syllable, and if the preceding vowel is stressed, it undergoes compensatory lengthening or breaking (diphthongization).

In many North American dialects, there are ten or eleven stressed monophthongs; only five or six vowel (rarely seven) contrasts are possible before a preconsonantal and word-final /r/ (beer, bear, burr, bar, bore, bor, boor).

(In North America, those distinctions are most likely to occur in New York City, Philadelphia, some of Eastern New England (including Boston), and in conservative Southern accents.)

The phenomenon that occurs in many dialects of the United States is one of tense–lax neutralization[1] in which the normal English distinction between tense and lax vowels is eliminated.

However, in Scotland, hurry /ˈhʌre/ is a perfect rhyme of furry /ˈfʌre/, but also the nurse mergers have never developed there, meaning that strut, dress and kit can all still exist before both intervocalic and coda /r/; thus, fur, fern, and fir have distinct vowels: /fʌr, fɛrn, fɪr/.

Dialects in England, Wales, and most others outside North America maintain the distinction between both sounds, so hurry and furry do not rhyme.

[citation needed] General American also often lacks a proper opposition between /ʌ/ and /ə/, which makes minimal pairs such as unorthodoxy and an orthodoxy variably homophonous as /ənˈɔrθədɑksi/.

In New Zealand English, there is a consistent contrast between hurry and furry, but the unstressed /ə/ is lengthened to /ɜː/ (phonetically [ɵː]) in many positions, particularly in formal or slow speech and especially when it is spelled ⟨er⟩.

It is common in the Philadelphia accent,[12] which does not usually have the marry–merry merger; its "short a" /æ/, as in marry and its SQUARE vowel /e/ remain distinct unmerged classes before /r/.

[13] Therefore, merry and Murray are both pronounced as [ˈmʌri], but marry [ˈmæri] and Mary [ˈmeri] are distinct from this merged pair (and each other).

[14] The mirror–nearer merger is absent from traditional, local, or non-standard accents of the Southern and Eastern United States, where nearer is pronounced with a tense monophthong [i] or a centering diphthong [iə ~ ɪə] (phonemicized as /i/ or /ɪə/, depending on whether the accent is rhotic or not), whereas mirror has a lax monophthong [ɪ].

In New York City, Long Island, and the nearby parts of New Jersey, those words are pronounced with [ɒr] like in Received Pronunciation.

[23][24] Areas of the United States in which the merger is most common include Central Texas, Utah, and St. Louis, but it is not dominant anywhere and is rapidly disappearing.

A similar merger is encountered in many varieties of American English, whose prevailing pronunciations are [oə] and [oɹ]⁓[ɔɹ], depending on whether or not the accent is rhotic.

[33] Some accents of southern British English, including many types of Received Pronunciation and in Norwich, have mergers of the vowels in words like tire, tar (which already merged with /ɑː/, as in palm), and tower.

[36][37] In the non-rhotic British accents that make the distinction, north is typically merged with thought, while the phonological status of force varies.

The areas of Wales that make the distinction merge it with the monophthongal variety of goat: /ˈfoːs/ (those accents lack the toe–tow merger).

[citation needed] In the accents of Northern England that lack the merger, force is not merged with any other lexical set; it is pronounced around [ɔː] while thought-north is a more open [ɒː].

[40] For many speakers, however, as noted by Henry Sweet, this contrast had by 1890 become constricted to word-final positions if the following word began with a consonant (so 'horse' and 'hoarse' had thus become homophonous, but not 'morceau' and 'more so').

[41] In his 1918 Outline of English Phonetics, Daniel Jones described the distinction as optional, but he still considered it to be frequently heard in 1962;[42][43] the two vowels are differentiated in the first (1884–1928) and second (1989) editions of the Oxford English Dictionary with the caveat that in most varieties of southern British pronunciation the two had become identical;[44][45] no distinction is drawn in the third edition,[46] as well as in most modern British dictionaries (Chambers being a notable exception).

For example, fieldwork performed in the 1930s by Kurath and McDavid showed the contrast to be robustly present in the speech of the entire Atlantic coast, as well as Vermont, northern and western New York State, Virginia, central and southern West Virginia, and North Carolina.

[48] Even in areas in which the distinction is still made, the acoustic difference between the [ɔɹ] of horse and the [oɹ] of hoarse was found to be rather small for many speakers.

[49] In the 2006 study, most white participants in only these American cities still resisted the merger: Wilmington, North Carolina; Mobile, Alabama; and Portland, Maine.

[52] In some Indian, Welsh, and Southern American dialects, the distinction between north and force may be maintained through the presence or absence of /r/, with horse being /hɔːs/ and hoarse being /hɔːrs/.

Note that in non-standard accents many words can shift their pronunciation without changing diaphonemes due to lexical diffusion.

What Scottish and older Irish English have in common is rhoticity without r-colored vowels, meaning that /r/ is used at the end of a syllable.

The vowel in fir /ɪr/ is usually distinct, but is liable to merge than /ər/ because their non-rhoticized equivalents /ɪ/ and /ə/ belong to the same phoneme; this parallels the hurry–furry merger.

Some older Southern American English varieties and some of England's West Country dialects have a partial merger of nurse–near.

There is evidence that the African American Vernacular English in Memphis, Tennessee, merges both /ɪr/ and /ɛər/ with /ɜr/, so here and hair are both pronounced the same as the strong pronunciation of her.

[70] It is also found in many neighbouring regions of historic Lancashire, such as Bolton, Wigan and Blackburn, where the quality is generally a more central [ɜː]~[ɵː].