Note: This article deals sound changes involving English-language diphthongs. Each of the following sound changes involved at least one phoneme which historically was a diphthong. The sound changes discussed here may also have involved a phoneme which was historically or is now a monophthong. For sound changes involving English-language centring diphthongs see "English-language vowel changes before historic r".
The vein-vain merger is the merger of the Middle English diphthongs
/ai/ and /ei/ that occurs in all dialects of present English.
As a result of the merger, vein and vain are now homophones, but in early Middle English they were pronounced differently as /vein/ and /vain/. Similarly day (from Old English dæġ) and way (from Old English weġ) did not rhyme before the merger.
The merged vowel was a diphthong, often transcribed /ɛi/. It later merged (in most dialects) with the /eː/ of words like pane in the pane-pain merger.
Long mid mergers
The earliest stage of Early Modern English
had a contrast between the long mid monophthongs (as in pane
respectively) and the diphthongs (as in pain
respectively). In the vast majority of Modern English
accents these have been merged, so that the pairs pane
are homophones. These mergers are grouped together by Wells as the long mid mergers.
The pane-pain merger is a merger of the long mid monophthong /eː/ and the diphthong /ɛi/ that occurs in most dialects of English. In the vast majority of Modern English accents the vowels have been merged; whether the outcome is monophthongal or diphthongal depends on the accent. But in a few regional accents, including some in East Anglia
, South Wales
, and even Newfoundland
, the merger has not gone through (at least not completely), so that pairs like pane
A distinction, with the pane words pronounced with [eː] and the pain words pronounced with [æɪ], survived in Norfolk English into the 20th century. Trudgill describes the disappearance of this distinction in Norfolk, saying that "This disappearance was being effected by the gradual and variable transfer of lexical items from the set of /eː/ to the set of /æɪ/ as part of dedialectalisation process, the end-point of which will soon be (a few speakers even today maintain a vestigial and variable distinction) the complete merger of the two lexical sets under /æɪ/ — the completion of a slow process of lexical diffusion.
Walters (2001) reports the survival of the distinction in the Welsh English spoken in the Rhondda Valley, with [eː] in the pane words and [ɛi] in the pain words.
In accents that preserve the distinction, the phoneme /eɪ/ is usually represented by the spellings ai, ay, ei and ey as in day, play, rain, pain, maid, rein, they etc. and the phoneme /eː/ is usually represented by aCe as in pane, plane, lane, late etc. and sometimes by eCe and e as in re, cafe, Santa Fe etc.
The toe-tow merger is a merger of the Early Modern English
vowels /oː/ (as in toe
) and /ɔu/ (as in tow
) that occurs in most dialects of English.
The merger occurs in the vast majority of Modern English accents; whether the outcome is monophthongal or diphthongal depends on the accent. But in a few regional accents, including some in Northern England, East Anglia and South Wales, the merger has not gone through (at least not completely), so that pairs like toe and tow, moan and mown, groan and grown, sole and soul, throne and thrown are distinct.
In nineteenth century England, the distinction was still very widespread; the main areas with the merger were in the northern Home Counties and parts of the Midlands. .
The distinction is most often preserved in East Anglian accents, especially in Norfolk. Peter Trudgill discusses this distinction, and states that "...until very recently, all Norfolk English speakers consistently and automatically maintained the nose-knows distinction... In the 1940s and 1950s, it was therefore a totally unremarkable feature of Norfolk English shared by all speakers, and therefore of no salience whatsoever."
In a recent investigation into the English of the Fens , young people in west Norfolk were found to be maintaining the distinction, with [ʊu] or [ɤʊ] in the toe set and a fronted [ɐʉ] in the tow set, with the latter but not the former showing the influence of Estuary English.
Walters (2001) reports the survival of the distinction in the Welsh English spoken in the Rhondda Valley, with [oː] in the toe words and [ou] in the tow words.
In accents that preserve the distinction, the phoneme descended from Early Modern English /ɔu/ is usually represented by the spellings ou, and ow as in soul, dough, tow, know, though etc., while that descended from Early Modern English /oː/ is usually represented by oa, oe, or oCe as in boat, road, toe, doe, home, hose, go, tone etc.
The cot-coat merger is phonomenum occurring for some speakers of Zulu English
where the phonemes /ɒ/ and /oʊ/ are not distinguished making "cot" and "coat" homophones. Zulu English
also generally has a merger of /ɒ/ and /ɔ/, so that sets like "cot", "caught" and "coat" can be homophones.
Poet-smoothing is a process occurring in many varieties of British English
where bisyllabic /əʊ.ə/ is pronounced as the diphthong /ɜɪ/ in many words. In these varieties, "poet" is pronounced as monosyllabic /pɜɪt/ and "poem" is pronounced as /pɜɪm/.
The rod-ride merger is a merger of /ɑ/ and /aɪ/ occurring for some speakers of African American Vernacular English
(AAVE), in which rod
are merged as /rɑd/. Some other speakers of AAVE may keep the contrast, so that rod
is /rɑd/ and ride
Scientific-smoothing is a process that occurs in many varieties of British English
where bisyllabic /aɪ.ə/ becomes the triphthong /aɪə/ in certain words with /aɪ.ə/. As a result, "scientific" is pronounced /saɪən.tɪf.ɪk/ with three syllables and "science" is pronounced as /saɪəns/ with one syllable.
The pride-proud merger is a merger of the diphthongs /aɪ/ and /ɑʊ/ before voiced consonants into monophthongal /ä/ occurring for some speakers of African American Vernacular English
etc. homophones. Some speakers with this merger, may also have the rod-ride merger
hence having a three-way merger of /ɑ/, /aɪ/ and /ɑʊ/ before voiced consonants, making pride
, and proud
The line-loin merger is a merger between the diphthongs /aɪ/ and /ɔɪ/ that occurs in some accents of Southern English English
, Newfoundland English
, and Caribbean English
. Pairs like line
are homophones in merging accents.
The coil-curl merger is a vowel merger
, now moribund, which historically occurred in some dialects of English. It is particularly associated with the dialects of New York
and New Orleans
The merger caused the vowel classes associated with the General American phonemes /ɔɪ/, as in choice, and /ɝ/, as in nurse, to merge, making coil and curl homophones. The merged vowel was typically a diphthong [ɜɪ], with a mid-central starting point, rather than the back rounded starting point of /ɔɪ/ in most other accents of English. The merger happened only before a consonant; stir and boy never rhymed.
The merger is responsible for the "Brooklynese" stereotypes of bird sounding like "boid" and thirty-third sounding like "toity-toid".
According to a survey that was done by William Labov in New York in 1966, 100% of the people over 60 used [ɜɪ] for bird. With each younger age group, however, the percentage got progressively lower: 59% of 50-59 year olds, 33% of 40-49 year olds, 24% of 20-39 year olds, and finally, only 4% of people 8-19 years old used [ɜɪ]. Nearly all native New Yorkers born since 1950, even those whose speech is otherwise non-rhotic, now pronounce bird as [bɝd].
The joy-point merger is the merger of the Middle English diphthongs
/ɔi/ and /ʊi/ that occurs in all dialects of present English.
As a result of the merger, joy and point now have the same vowel, but in Middle English they had different vowels and were pronounced /dʒɔi/ and /pʊint/.
/ɔi/ and /ʊi/ fell together as present day /ɔɪ/ so that joy and point are now pronounced /dʒɔɪ/ and /pɔɪnt/.
The sounds /ɔi/ and /ʊi/ were brought into Middle English as a result of French influence (for example, English "coy" came from Old French "coi").
The Middle English diphthongs /ɔi/ and /ʊi/ were spelt with the same graphemes for example oi and oy.
The mare-mayor merger is a process occurring in many varieties of British English
where bisyllabic /eɪ.ə/ is pronounced as the central diphthong /ɛə/ in many words. In these varieties, "mayor" is pronounced /mɛə/, homophonous with "mare".