InEnglish, manyvowel shifts affect only vowels followed by/r/ inrhotic dialects, or vowels that were historically followed by/r/ that has been elided in non-rhotic dialects. Most of them involve the merging ofvowel distinctions, so fewer vowelphonemes occur before/r/ than in other positions of a word.

In rhotic dialects,/r/ is pronounced in most cases. InGeneral American English (GA),/r/ is pronounced as an approximant[ɹ] or[ɻ] in most positions, but after some vowels, it is pronounced asr-coloring. InScottish English,/r/ is traditionally pronounced as a flap[ɾ] or trill[r], and there are nor-colored vowels.

In non-rhotic dialects likeReceived Pronunciation (RP), historic/r/ iselided at theend of a syllable, and if the preceding vowel is stressed, it undergoescompensatory lengthening orbreaking (diphthongization). Thus, words that historically had/r/ often havelong vowels orcentering diphthongs ending in a schwa/ə/, or a diphthong followed by a schwa.

• earth: GA[ɝθ], RP[ɜːθ]
• here: GA[ˈhɪɚ], RP[ˈhɪə]
• fire: GA[ˈfaɪɚ], RP[ˈfaɪə]

In most English dialects, there are vowel shifts that affect only vowels before/r/ or vowels that were historically followed by/r/. Vowel shifts before historical/r/ fall into two categories: mergers and splits. Mergers are more common, so most English dialects have fewer vowel distinctions before historical/r/ than in other positions of a word.

In manyNorth American dialects, there are ten or eleven stressedmonophthongs; only five or six vowel (rarely seven) contrasts are possible before a preconsonantal and word-final/r/ (beer, bear, burr, bar, bore, bor, boor). Often, more contrasts exist if/r/ appears between vowels of different syllables. In some American dialects and in most native English dialects outside North America, for example,mirror andnearer do notrhyme, and some or all ofmarry,merry, andMary are pronounced distinctly. (In North America, those distinctions are most likely to occur inNew York City,Philadelphia, some of Eastern New England (includingBoston), and in conservativeSouthern accents.) In many dialects, however, the number of contrasts in that position tends to be reduced, and the tendency seems to be towards further reduction. The difference in how the reductions have been manifested represents one of the greatest sources of cross-dialect variation.

Non-rhotic accents in many cases show mergers in the same positions as rhotic accents even though there is often no/r/ phoneme present. That results partly from mergers that occurred before the/r/ was lost and partly from later mergers of the centering diphthongs and long vowels that resulted from the loss of/r/.

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

In some cases, the quality of a vowel before/r/ is different from the quality of the vowel elsewhere. For example, in some dialects ofAmerican English, the quality of the vowel inmore typically does not occur except before/r/, and it is somewhere in between the vowels ofmaw andmow. It is similar to the vowel of the latter word but without theglide.

It is important to note, however, that different mergers occur in different dialects. Generally, these correlate to accents withrhotic vowels, as opposed to non-rhoticity (as in most ofBritish English) or fully pronounced/r/ (as inScottish English).

Most North American English dialects merge the lax vowels with the tense vowels before/r/, so "marry" and "merry" have the same vowel as "mare", "mirror" has the same vowel as "mere", "forest" has the same vowel as the stressed form of "for", and "hurry" has the same vowel as "stir" as well as that found in the second syllable of "letter". The mergers are typically resisted by non-rhotic North Americans and are largely absent in areas of the United States that are historically largely non-rhotic.

Thehurry–furry merger occurs when the vowel/ʌ/ before intervocalic/r/ is merged with/ɜ/. That is particularly a feature in many dialects ofNorth American English but notNew York City English,Mid-Atlantic American English,older Southern American English, some speakers ofEastern New England English,^[2] and speakers ofSoutheastern New England English. Speakers with the merger pronouncehurry to rhyme withfurry andturret to rhyme withstir it.

To occur, the merger requires thenurse mergers to be in full effect, which is the case in nearly all English dialects worldwide, particularly outside the British Isles. However, in Scotland,hurry/ˈhʌre/ is a perfect rhyme offurry/ˈfʌre/, but also thenurse mergers have never developed there, meaning thatstrut,dress andkit can all still exist before both intervocalic and coda/r/; thus,fur,fern, andfir have distinct vowels:/fʌr,fɛrn,fɪr/.

Dialects in England, Wales, and most others outside North America maintain the distinction between both sounds, sohurry andfurry do not rhyme.^[2] However, in dialects without thefoot–strut split,hurry has an entirely different vowel:/ˈhʊri/ (in a number of those dialects, asquare–nurse merger is in effect instead).

General American has a three-way merger between the first vowels inhurry andfurry and the unstressed vowel inletters. In Received Pronunciation, all of them have different sounds (/ʌ/,/ɜː/ and/ə/, respectively), and some minimal pairs exist between unstressed/ɜː/ and/ə/, such asforeword/ˈfɔːwɜːd/ vs.forward/ˈfɔːwəd/. In General American, they collapse to[ˈfɔrwɚd], but in phonemic transcription, they can still be differentiated as/ˈfɔrwɜrd/ and/ˈfɔrwərd/ to facilitate comparisons with other accents.^{[citation needed]} General American also often lacks a proper opposition between/ʌ/ and/ə/, which makes minimal pairs such asunorthodoxy andan orthodoxy variably homophonous as/ənˈɔrθədɑksi/.^[3] See thestrut–comma merger for more information.

InNew Zealand English, there is a consistent contrast betweenhurry andfurry, 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⟩. Thus,boarded andbordered might be distinguished as/ˈbɔːdəd/ and/ˈbɔːdɜːd/, which is homophonous inAustralian English as/ˈbɔːdəd/ and distinguished in Received Pronunciation as/ˈbɔːdɪd/ and/ˈbɔːdəd/, based on the length and the rounding of/ɜː/. The shift was caused by a complete phonemic merger of/ɪ/ and/ə/, aweak vowel merger that was generalized to all environments.^[4]

One notable merger of vowels before/r/ is theMary–marry–merry merger,^[5] a merging of the vowels/æ/ (as in the nameCarrie or the wordmarry) and/ɛ/ (as inKerry ormerry) with the historical/eɪ/ (as inCary orMary) whenever they are realized before intervocalic/r/. No contrast exists before a final or preconsonantal/r/, where/æ/ merged with/ɑ/ and/ɛ/ with/ɜ/ (seenurse mergers) centuries ago.^[6] The merger is fairly widespread and is complete or nearly complete in most varieties of North American English,^{[sample 1]} but it is rare in other varieties of English. The following variants are common in North America:

• The fullMary–marry–merry merger (also known, in this context, as the three-way merger) is found throughout much of the United States (particularly the Western and Central United States) and in all of Canada except Montreal.^{[citation needed]} This is found in about 57% of American English speakers, according to a 2003 dialect survey.^[5] The merger is highlighted in the songMerry Go 'Round, whose central wordplay revolves around "Mary", "marry", and "merry" having the exact same pronunciation in the singer's accent.
• No merger, also known as a three-way contrast, exists in North America primarily in the Northeastern United States and is most clearly documented in the accents ofPhiladelphia,New Jersey,New York City,Rhode Island, andBoston. In thePhiladelphia accent, the three-way contrast is preserved, butmerry tends to be merged withMurray (seemerry–Murray merger below). The three-way contrast is found in about 17% of American English speakers overall.^{[5][7][sample 2]}
• TheMary–marry merger is found alone with 16% of American English speakers overall, with the highest concentration inNew England, especiallyNew Hampshire.^[5]
• TheMary–merry merger is found alone among 9% of American English speakers overall, concentrated in the American South, especiallyLouisiana where it is the most common variant,^[8] and the Southern part of theMid-Atlantic region.^[5][9] It is also found amongAnglophones inMontreal.
• Themerry–marry merger is found alone rarely, with about 1% of American English speakers.

In accents without the merger,Mary has thea sound ofmare,marry has the "shorta" sound ofmat, and merry has the "shorte" sound ofmet. In modern Received Pronunciation, they are pronounced as[ˈmɛːɹiː],[ˈmaɹiː], and[ˈmɛɹiː]; in Australian English, as[ˈmeːɹiː],[ˈmæɹiː~ˈmaɹiː], and[ˈmeɹiː]; in New York City English, as[ˈmeɹi⁓ˈmɛəɹi],[ˈmæɹi], and[ˈmɛɹi]; and in Philadelphia English, the same as New York City exceptmerry is[ˈmɛɹi⁓ˈmʌɹi]. There is plenty of variance in the distribution of the merger, with expatriate communities of those speakers being formed all over the country.

TheMary–merry merger is possible in New Zealand, and the quality of the merged vowel is then[e̝] (similar tokit in General American). However, in New Zealand, the vowel inMary often merges with thenear vowel/iə/ instead (seenear–square merger), which before intervocalic/r/ may then merge with/iː/, soMary (phonemically/ˈmeəriː/) can be[ˈmiəɹiː] or[ˈmiːɹiː] instead. In all of those cases, there is a clear distinction betweenMary andmerry (regardless of how both are pronounced) andmarry/ˈmɛriː/ (with thetrap vowel) on the other.^[10]

Themerry–Murray merger, also known as thefurry–ferry merger, is a merger of/ɛ/ and/ʌ/ before/r/, with the resulting vowel being[ʌ]. It is common in thePhiladelphia accent,^[12] which does not usually have themarry–merry merger; its "short a"/æ/, as inmarry and its SQUARE vowel/e/ remain distinct unmerged classes before/r/.^[13] Therefore,merry andMurray are both pronounced as[ˈmʌri], butmarry[ˈmæri] andMary[ˈmeri] are distinct from this merged pair (and each other).

The mergers of/ɪr/ and/iːr/ (as inmirror andnearer, orSirius andserious, respectively) and/ʊr/–/uːr/ occur in North American English as a part of pre-/r/ laxing, together with theMary–merry andhorse–hoarse mergers. The phonetic outcome of the first merger is either a lax vowel[ɪ], or a somewhat raised vowel that approaches the monophthongal allophone offleece:[i̞], often diphthongal as[ɪə~iə]. In the case of the/ʊr/–/uːr/ merger, it tends to approach the monophthongal variant ofgoose:[ʊ̝].^[14]

Themirror–nearer merger is absent from traditional, local, or non-standard accents of the Southern and Eastern United States, wherenearer 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), whereasmirror has a lax monophthong[ɪ].^[15]

In the case of the first merger, only a handful of minimal pairs (e.g.,cirrus–serous andSirius–serious) illustrate the contrast, in addition to morphologically distinct pairs (e.g.,spirit–spear it), all of which are rendered homophonous by the merger. Indeed, the number of the words containing/ɪr/ is itself low. There are a few minimal pairs contrasting/ʊə/and/u:ə/ in conservative Received Pronunciation:dour–doer,sure–shoer andcure-queuer. Furthermore, thehurry–furry merger that occurs in most varieties of North American English results in a merger of/ʌr/ with/ɜr/, removing almost any trace of the historicalfoot vowel in this position. Instead, it is a simple replacement of one phoneme with another, so that the wordtour/tʊr/ is perceived to contain thefoot vowel, rather than thegoose vowel. However, this change may not hold where morpheme boundaries apply; allowing a qualitative distinction to be maintained between the stressed vowels intourist/ˈtʊrəst/ (a fairly close back monophthong of variable height) on the one hand, andtwo-wrist/ˈturɪst/ (a fully close monophthong in free variation with a narrow closing diphthong) on the other (cf. traditional RP/ˈtʊərɪst,ˈtuːrɪst/). The same applies to themirror–nearer merger, which laxes the vowel inclearing/ˈklɪrɪŋ/ but not inkey ring/ˈkirɪŋ/, cf. RP/ˈklɪərɪŋ,ˈkiːrɪŋ/. Certain words are pronounced as if they contained a morpheme boundary before/r/, notablyhero/ˈhiroʊ/ andzero/ˈziroʊ/.^[16]

Some words originally containing the/uːr/ sequence are merged with eitherforce (seecure–force merger) or, more rarely,nurse (seecure–nurse merger) instead offoot +/r/.^[17]

Themirror–nearer and/ʊr/–/uːr/ mergers are not to be confused with thefleece–near andgoose–cure mergers that occur in some non-rhotic dialects before a sounded/r/ and which do not involve the lax vowels/ɪ/ and/ʊ/.^{[clarification needed][citation needed]}

Words with a stressed/ɒ/ before intervocalic/r/ in Received Pronunciation are treated differently in different varieties ofNorth American English. As shown in the table below, inCanadian English, all of them are pronounced with[-ɔr-], as incord. In the accents ofPhiladelphia,^[18]southern New Jersey, andthe Carolinas^[19] (and traditionally throughout the whole South), those words are pronounced by some with[-ɑr-], as incard and so merge with historic prevocalic/ɑr/ in words likestarry. InNew York City,Long Island, andthe nearby parts of New Jersey, those words are pronounced with[ɒr] like in Received Pronunciation. However, the sound ismet with change to/ɑr/ and so still merges with the historic prevocalic/ɑr/ instarry.^[20]

On the other hand, the traditionalEastern New England accents (especially aroundBoston), the words are pronounced with[-ɒr-], but thecot–caught merger still applies elsewhere. In that regard, it is the same as Canadian/ɒ/, rather than Received Pronunciation/ɒ/. Most of the rest of the United States (marked "General American" in the table), however, has a distinctive mixed system.^[21]

In accents with thehorse–hoarse merger,/ɔr/ also includes the historic/oʊr/ in words such asglory andforce. When an accent also features thecot–caught merger,/ɔr/ is typically analyzed as/oʊr/ to avoid postulating a separate/ɔ/ phoneme that occurs only before/r/. Therefore, bothcord andglory are considered to contain the/oʊ/ phoneme in California, Canada, and elsewhere. Therefore, in accents with the horse–hoarse merger,/kɔrd/ and/koʊrd/ are different analyses of the same wordcord, and there may be little to no difference in the realization of the vowel.^[22]

In the varieties of Scottish English with thecot–caught merger, the vowel is pronounced towards the[ɔ] ofcaught andnorth. It remains distinct from the[o] offorce andgoat because of the lack of thehorse–hoarse merger.^[23]

Even in the American East Coast without the split (Boston, New York City, Rhode Island, Philadelphia and some of the coastal South), some of the words in the original short-o class often show influence from other American dialects and end up with[-ɔr-] anyway. For instance, some speakers from the Northeast pronounceFlorida,orange, andhorrible with[-ɑr-] butforeign andorigin with[-ɔr-]. The list of words affected differs from dialect to dialect and occasionally from speaker to speaker, which is an example of sound change bylexical diffusion.

TheMiddle English merger of the vowels with the spellings⟨our⟩ and⟨ower⟩ affects all modern varieties ofEnglish and causes words likesour andhour, which originally had one syllable, to have two syllables and so to rhyme withpower. In accents that lack the merger,sour has one syllable, andpower has two syllables. Similar mergers also occur in whichhire gains a syllable and so makes it pronounced likehigher, andcoir gains a syllable and so makes it pronounced likecoyer.^[24]

Thecard–cord merger, orstart–north merger, is a merger ofEarly Modern English[ɑr] with[ɒr], which results in thehomophony of pairs likecard/cord,barn/born andfar/for. It is roughly similar to thefather–bother merger but beforer. The merger is found in someCaribbean English accents, in someWest Country accents in England, and in some accents ofSouthern American English.^[25][26] Areas of the United States in which the merger is most common includeCentral Texas,Utah, andSt. Louis, but it is not dominant anywhere and is rapidly disappearing.^[27] Rhotic dialects with thecard–cord merger are some of the only ones without thehorse–hoarse merger; this correlation is well-documented in the United States.^[27]

InModern English, the reflexes of Early Modern English/uːr/ and/iur/ are highly susceptible tophonemic mergers with other vowels. Words belonging to that class are most commonly spelled withoor,our,ure, oreur. Examples includepoor,tour,cure,Europe (words such asmoor ultimately fromOld Englishō words). Wells refers to the class as thecure words after the keyword of thelexical set to which he assigns them.

In traditionalReceived Pronunciation andGeneral American,cure words are pronounced with Received Pronunciation/ʊə/ (/ʊər/ before a vowel) and General American/ʊr/.^[28] However, those pronunciations are being replaced by other pronunciations in many accents.

InSouthern England,cure words are often pronounced with/ɔː/, somoor is often pronounced/mɔː/,tour/tɔː/, andpoor/pɔː/.^[29] The traditional form is much more common in Northern England. A similar merger is encountered in many varieties ofAmerican English, whose prevailing pronunciations are[oə] and[oɹ]⁓[ɔɹ], depending on whether or not the accent is rhotic.^[30][31] For many speakers of American English, the historical/iur/ merges with/ɜr/ after palatal consonants, as in "cure", "sure", "pure", and "mature", and merges with/ɔr/ in other environments such as in "poor" and "moor".^[32]

InAustralian andNew Zealand English, the centeringdiphthong/ʊə/ has mostly disappeared and is replaced in some words by/ʉːə/ (a sequence of two separatemonophthongs) and in others by/oː/ (a long monophthong).^[33] The outcome that occurs in a particular word is not always predictable although, for example,pure,cure, andtour may rhyme withfewer and have/ʉːə/, andpoor,moor, andsure rhyme withfor andpaw and have/oː/.

InEast Anglia, acure–nurse merger in which words likefury merge to the sound offurry[ɜː] is common, especially afterpalatal andpalatoalveolar consonants, sosure is often pronounced[ʃɜː], which is also a common single-word merger in American English in which the wordsure is often/ʃɜr/. Also,yod-dropping may apply, which yields pronunciations such as[pɜː] forpure. Other pronunciations in the accents that mergecure andfir include/pjɜː(r)/pure,/ˈk(j)ɜːriəs/curious,/ˈb(j)ɜːroʊ/bureau and/ˈm(j)ɜːrəl/mural.^[34]

Varieties ofSouthern American English,Midland American English andHigh Tider English may merge words likefire andfar ortired andtarred towards of the second words:/ɑr/. That results in atire–tar merger, buttower is kept distinct.^[35]

Some accents of southernBritish English, including many types of Received Pronunciation and inNorwich, have mergers of the vowels in words liketire,tar (which alreadymerged with/ɑː/, as inpalm), andtower. Thus, the triphthong/aʊə/ oftower merges with the/aɪə/ oftire (both surface as diphthongal[ɑə]) or with the/ɑː/ oftar. Some speakers merge all three sounds, sotower,tire, andtar are all pronounced[tɑː].^[36]

Thehorse–hoarse merger, ornorth–force merger, is the merger of the vowels/ɔː/ and/oʊ/ before historic/r/, which makes word pairs likehorse–hoarse,for–four,war–wore,or–oar,morning–mourning pronounced the same. Historically, thenorth class belonged to theEarly Modern English/ɒ/ phoneme (containing the same vowel aslot), while theforce class was/oː/ (containing the same vowel asgo).

The merger now occurs in most varieties of English. Accents that have resisted the merger include mostScottish andCaribbean accents as well as someAfrican American,Southern American,Indian,Irish,older Maine,South Wales (excluding Cardiff), someNorthern English (particularlyManchester^[37]), andWest Midlands accents.^[38][39]

In the non-rhotic British accents that make the distinction,north is typically merged withthought, while the phonological status offorce varies. The areas of Wales that make the distinction merge it with the monophthongal variety ofgoat:/ˈfoːs/ (those accents lack thetoe–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] whilethought-north is a more open[ɒː].^[37] In the West Midlands,force corresponds to eithergoat +comma:/ˈfʌʊəs/ or a separate/oə/ phoneme:/ˈfoəs/. The words belonging to each set vary to an extent region to region, for example from Port Talbot tend to useforce, instead of the traditionalnorth, inforceps,fortress,important andimportance.^[40][41]

The distinction was once present in the speech of southern England, theNORTH vowel being sounded as/ɔː/ and theFORCE vowel as the centring diphthong/ɔə/.^[42] For many speakers, however, as noted byHenry 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 becomehomophonous, but not 'morceau' and 'more so').^[43] In his 1918Outline of English Phonetics,Daniel Jones described the distinction as optional, but he still considered it to be frequently heard in 1962;^[44][45] the two vowels are differentiated in the first (1884–1928) and second (1989) editions of theOxford English Dictionary with the caveat that in most varieties of southern British pronunciation the two had become identical;^[46][47] no distinction is drawn in the third edition,^[48] as well as in most modern British dictionaries (Chambers being a notable exception).John C. Wells wrote in 2002 that the distinction had become obsolete in RP.^[42]

In the United States, the merger is now widespread everywhere but is quite recent in some parts of the country. For example, fieldwork performed in the 1930s byKurath and McDavid showed the contrast to be robustly present in the speech of the entire Atlantic coast, as well asVermont, northern and westernNew York State,Virginia, central and southernWest Virginia, andNorth Carolina.^[49][27] However, by the 1990s, surveys showed those areas had completely or almost completely undergone the merger.^[50] Even in areas in which the distinction is still made, the acoustic difference between the[ɔɹ] ofhorse and the[oɹ] ofhoarse was found to be rather small for many speakers.^[27] Some American speakers retain the original length distinction but merge the quality. Therefore,hoarse[hɔːrs] is pronounced longer thanhorse[hɔrs].^[51]

In the 2006 study, most white participants in only these American cities still resisted the merger:Wilmington, North Carolina;Mobile, Alabama; andPortland, Maine.^[52] A 2013 study of Portland, however, found the merger to have been established "at all age levels".^[53] In the 2006 study, evenSt. Louis, Missouri, which traditionally maintained thehorse–hoarse distinction so strongly that it insteadmergedcard andcord, showed that only 50% of the participants still maintained the distinction. The same pattern (ahorse–hoarse distinction and acard–cord merger) also exists in a minority of speakers in Texas and Utah. New Orleans prominently shows much variability regarding the merger, including some speakers with no merger at all. Black Americans are rapidly undergoing the merger but are also less likely to do so than white Americans, with a little over half of the 2006 study's black participants maintaining the distinction nationwide.^[54]

In someIndian,Welsh, andSouthern American dialects, the distinction betweennorth andforce may be maintained through the presence or absence of/r/, withhorse being/hɔːs/ andhoarse being/hɔːrs/.^[55]

The two groups of words merged by the rule are called thelexical setsnorth (includinghorse) andforce (includinghoarse) by Wells (1982).

In dialects that maintain the distinction between the two phonemes,north is indicated almost exclusively by the spellingsor,aur andar (when preceded by /w/), as inhorse,aural,war, whileforce is generally indicated by the spellingsoar,ore,our andoor, as inhoarse,wore,four,door.

However,force can also sometimes occur in words with theor spelling. This is usually in one or more of the following circumstances:

• When the vowel immediately follows alabial consonant,/mpbfvw(ʍ)/, as inforce itself.
• Inpast participles in-orn with correspondingpast tense forms in-ore, as intorn, or words made from ones with theforce vowel.
• When the /r/ is followed by a vowel within the samemorpheme, as in words likeglory andflora.

However, it does not occur in all words that fit the above criteria. The following table lists some words irregularly with theforce sound, rather thannorth, with the cases that make them so and regularnorth words by comparison. Note that in non-standard accents many words can shift their pronunciation without changingdiaphonemes due tolexical diffusion.

Thenear–square merger orcheer–chair merger is the merger of the Early Modern English sequences/iːr/ and/ɛːr/, as well as the/eːr/ between them, and is found in some accents of Modern English. Many speakers in New Zealand^[58][59][60] merge them towards thenear vowel, but some speakers inEast Anglia andSouth Carolina merge them towards thesquare vowel.^[61] The merger is widespread in Caribbean English, includingJamaican English.

Common in a vast majority of modern English dialects worldwide is the merger of as many as fiveEarly Modern English vowels (/ɛ/,/ɛː/,/ə/,/ɪ/, and/ʊ/) into/ɜ/ when followed by an/r/ before a consonant or at the end of a syllable. Thus, the vowels in words likefir,fur, andfern are the same in almost all modern accents of English.John C. Wells briefly calls it theNURSE merger.^[62] When another vowel follows, these are often distinct; contrast the vowels inmerry,hurry,weary,mirror, andfurry (see theMary–marry–merry merger,mirror–nearermerger, andhurry–furry merger for details). The major exceptions to most of theNurse mergers areScottish English and olderIrish English, which also do not have mergers of vowels before/r/ following another vowel. What Scottish and older Irish English have in common isrhoticity withoutr-colored vowels, meaning that/r/ is used at the end of a syllable.

Words and names with historic/ɛːr/ are spelled⟨ear⟩ as inearn,earth orpearl and include the function wordsher andwere, in⟨are, air, eir, ayer⟩ which have stayed distinct (see both themeet–meat andpane–pain mergers). The relevant words and names with historic/ɛr/ are⟨er⟩ in a stressed syllable, historic/ʊr/ are spelled as a stressed⟨ur ,or ,our⟩, and/ɪr/ is any⟨ir⟩ or⟨yr⟩. The diaphoneme/ər/ originates from unstressed vowels before/r/ and was not otherwise distinct.

Scottish English and rural Irish English dialects both use sequences of a vowel then/r/ notr-colored vowels, and both lack thefoot–strut split; which result in comparable developments. However, the actual realizations of the retainedNurse vowels vary. Also, while most of Scottish English has some distinction, more prestigious/ younger Irish English realizes theNurse merger as[ɝː]. The table below summarizes the overall differences:

InScottish English,mid front/ɛːr/ and/ɛr/ are merged into/er/, paralleling themid back vowelhorse–hoarse merger, which Scottish English lacks. The vowel infir/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 thehurry–furry merger. All EME/ʊ/ became/ʌ/, which included before/r/. The/ər/ (letter),/er/ (term) and/ʌr/ (fur) vowels are fully distinct from each other.

For rural and very conservativeIrish English,/ɪr/ (inwhirl) merges entirely with/ɛːr/ (inearl), sometimes merging again with/ɛr/. The merged/ɛːr/ merges again with/ʊr/ afterlabials andcoronalplosives (including/θ/ and/ð/ becoming/t̪/ and/d̪/) in many common words, but this no longer productive.

Someolder Southern American English varieties and some of England'sWest Country dialects have a partial merger ofnurse–near. They generally pronouncenear as/njɜr/, which rhymesnear with anurse word likesir orfur (compare general English realisations ofcue andcoo). Words such asbeard are then pronounced as/bjɜrd/.^[63] Usual word pairs likebeer andburr are still distinguished as/bjɜr/ and/bɜr/. However,/j/ is dropped after aconsonant cluster (as inqueer) or apalato-alveolar consonant (as incheer), likely because ofphonotactic constraints, which then results in a merger withnurse:/kwɜr/,/tʃɜr/.

There is evidence that theAfrican American Vernacular English inMemphis, Tennessee, merges both/ɪr/ and/ɛər/ with/ɜr/, sohere andhair are both pronounced the same as the strong pronunciation ofher.^[64]

Thenurse–north merger (words likeperk being pronounced likepork) involves the merger of/ɜː/ with/ɔː/ and occurs inbroadestGeordie.^[65]

Somethought words (roughly those spelled witha) have a distinct[aː] vowel in broad Geordie.^[66] Therefore, the merger involves only some of the words corresponding to historical/ɔː/ in Received Pronunciation.

Thesquare–nurse merger, orfair–fur merger, is a merger of/ɛə(r)/ with/ɜː(r)/ that occurs in some accents likeScouse, various other dialects within historicLancashire,Teesside,Hull, the newerDublin, and theBelfast accents.^{[67][68][69][70][71]}

Scouse, the accent of Liverpool and the Merseyside area, is the dialect with which the merger is most stereotypically associated.^[68] The most common realization in modern Scouse is [eː], but [ɛː] and [ɪː] are also possible.^[72] It is also found in many neighbouring regions of historic Lancashire, such asBolton,Wigan andBlackburn, where the quality is generally a more central [ɜː]~[ɵː].^[68] Shorrocks (1999) reports that in the dialect ofBolton, Greater Manchester, the two sets are generally merged to [ɵ:], but somenurse words such asfirst have a short [ɵ].^[73]

The merger can also be found among some speakers in the Teesside conurbation and the Humberside (Hull -East Riding of Yorkshire -North East Lincolnshire) area with a quality intermediate between [ɛː] and [ɜː].^[68]

Thorne (2003) reports that thesquare–nurse merger also occurs inBirmingham, remarking the merger as being "another principally northern characteristic". Tennant (1982) reportsnurse as being pronounced as /eə/ - which would leadsquare andnurse as being pronounced the opposite way of their RP pronunciation.^[74]

The merger is found in some varieties ofAfrican American Vernacular English and is pronounced[ɚ]: "A recent development reported for someAAE (in Memphis, but likely found elsewhere)."^[75] This is exemplified inChingy's song "Right Thurr", in which the merger is spelled in the title.

Labov (1994) also reports such a merger in some western parts of the United States "with a high degree of r constriction".

• Phonological history of English
• Phonological history of English vowels
• Coil–curl merger
• English phonology
• History of English
• R-colored vowel