Phonological history of English diphthongs


The phonological history of English diphthongs comprises sound changes to phonemes that have historically been diphthongs in the English language.

Background

English diphthongs have undergone many changes since the Old and Middle English periods. The sound changes discussed here involved at least one phoneme which historically was a diphthong.

Old English

Old English diphthongs could be short or long. Both kinds arose from sound changes occurring in Old English itself, although the long forms sometimes also developed from Proto-Germanic diphthongs. They were mostly of the height-harmonic type with the second element further back than the first. The set of diphthongs that occurred depended on dialect. Typical diphthongs are considered to have been as follows:
  • high, fully backing,, spelt
  • high, narrower, possibly, spelt
  • mid,, spelt
  • low,, spelt
As with monophthongs, the length of the diphthongs was not indicated in spelling, but in modern editions of OE texts the long forms are often written with a macron:,,,.
In the transition from Old to Middle English, all of these diphthongs generally merged with monophthongs.

Middle English

Development of new diphthongs

Although the Old English diphthongs merged into monophthongs, Middle English began to develop a new set of diphthongs. Many of these came about through vocalization of the palatal approximant or the labio-velar approximant, when they followed a vowel. For example:
  • OE dæg and weg became and
  • OE clawu and lagu became and
Diphthongs also arose as a result of vowel breaking before . For example:
  • OE streht became
  • OE þoht became
The diphthongs that developed by these processes also came to be used in many loanwords, particularly those from Old French. For a table showing the development of the Middle English diphthongs, see Middle English phonology (diphthong equivalents).

''Vein–vain'' merger

Early Middle English had two separate diphthongs and. The vowel was typically represented orthographically with "ei" or "ey", and the vowel was typically represented orthographically with "ai" or "ay". These came to be merged, perhaps by the fourteenth century. The merger is reflected in all dialects of present-day English.
In early Middle English, before the merger, way and day, which came from Old English weġ and dæġ had and respectively. Similarly, vein and vain were pronounced differently as and. After the merger, vein and vain were homophones, and way and day rhymed.
The merged vowel was a diphthong, something like or. Later this diphthong would merge in most dialects with the monophthong of words like pane in the pane–pain merger.

Late Middle English

The English of southeastern England around 1400 had seven diphthongs, of which three ended in :
  • as in boil, destroy, coin, join
  • as in nail, day, whey
  • as in joy, noise, royal, coy
and four ended in :
  • as in view, new, due, use, lute, suit, adieu
  • as in few, dew, ewe, shrewd, neuter, beauty
  • as in low, soul
  • as in cause, law, salt, change, chamber, psalm, half, dance, aunt.
Typical spellings are as in the examples above. The spellings eu and ew are both and, and the spellings oi and oy are used for both and. The most common words with ew pronounced were dew, few, hew, lewd, mew, newt, pewter, sew, shew, shrew, shrewd and strew. Words in which was commonly used included boil, coin, destroy, join, moist, point, poison, soil, spoil, Troy, turmoil and voice, although there was significant variation.

Modern English

16th century

By the mid-16th century, the Great Vowel Shift had created two new diphthongs out of the former long close monophthongs and of Middle English. The diphthongs were as in tide, and as in house. Thus, the English of south-eastern England could then have had nine diphthongs.
By the late 16th century, the inventory of diphthongs had been reduced as a result of several developments, all of which took place in the mid-to-late 16th century:
  • merged into and so dew and due became homophones.
  • became monophthongized and merged with the of words like name. For more information, see pane–pain merger, below.
  • * For a time, many speakers had an monophthong in pain distinct from an monophthong in pane.
  • , as in cause, became monophthongized to, later raising to modern.
  • , as in low, was monophthongized to That would later rise to, which merged with the vowel of toe; see toe–tow merger, below.
That left,,, and as the diphthongs of south-eastern England.

17th century

By the late 17th century, these further developments had taken place in the dialect of south-eastern England:
  • The falling diphthong of due and dew changed to a rising diphthong, which became the sequence. The change did not occur in all dialects, however; see Yod-dropping.
  • The diphthongs and of tide and house widened to and, respectively.
  • The diphthong merged into ~. Contemporary literature had frequent rhymes such as Mind–''join'd in Congreve, joinline in Pope, childspoil'd in Swift, toilssmiles in Dryden.
  • The diphthong split into and, though this sound change was still ongoing in the late 18th century. The present-day pronunciations with in the oi'' words result from regional variants, which had always had, rather than, perhaps because of influence by the spelling.
The changes above caused only the diphthongs, and to remain.

Later developments

In the 18th century or later, the monophthongs became diphthongal in Standard English. That produced the vowels and. In RP, the starting point of the latter diphthong has now become more centralized and is commonly written.
RP has also developed centering diphthongs,,, as a result of breaking before /r/ and the loss of when it is not followed by another vowel. They occur in words like near, square and cure.
Present-day RP is thus normally analyzed as having eight diphthongs: the five closing diphthongs,,,, and the three centering diphthongs,,. General American does not have the centering diphthongs. For more information, see English phonology (vowels).

Variation in present-day English

''Coil''–''curl'' merger

The coil–''curl or oilearl'' merger is a vowel merger that historically occurred in some non-rhotic dialects of American English, making both and become. This is strongly associated with New York City English and New Orleans English, but only the latter has any modern presence of the feature.

''Cot''–''coat'' merger

The cot–''coat'' merger is a phenomenon exhibited by some speakers of Zulu English in which the phonemes and are not distinguished, making "cot" and "coat" homophones. Zulu English often also has a cot-caught merger, so that sets like "cot", "caught" and "coat" can be homophones.
This merger can also be found in some broad Central Belt Scottish English accents. The merger of both sounds into is standard in Central Scots.

''Line''–''loin'' merger

The line–''loin merger is a merger between the diphthongs and that occurs in some accents of Southern English English, Hiberno-English, Newfoundland English, and Caribbean English. Pairs like line and loin, bile and boil, imply and employ'' are homophones in merging accents.
IPA
aisleoil
allyalloy
bileboil
buy, by, bye, buyboy, buoy
dividedevoid
drieddroid
filefoil
firefoyer
grindgroined
guygoy
heisthoist
hi, highhoy
Ioi, oy
I'll, isleoil
implyemploy
Jainjoin
Kaicoy, koi
kinecoin
Kylecoil
liarlawyer
liedLloyd
lineloin
Lyleloyal
lyrelawyer
milemoil
nighsnoise
Nilenoil
piepoi
piespoise
pintpoint
plyploy
psisoy
quitequoit
rideroid
rileroil
rileroyal
ryeRoy
sighsoy
siresawyer
siresoya
Thai, tietoy
tidetoyed
tiletoil
tryTroy
vicevoice
viedvoid
wryRoy

Long mid mergers

The earliest stage of Early Modern English had a contrast between the long mid monophthongs and the diphthongs . In the vast majority of Modern English accents these have been merged, so that the pairs pane–''pain and toetow are homophones. These mergers are grouped together by Wells as the long mid mergers. All accents with the pane–pain merger have the toe–tow'' merger and vice versa.

''Pane''–''pain'' merger

The pane–''pain merger is a merger of the long mid monophthong and the diphthong 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. However, in a few regional accents, including some in East Anglia, South Wales, South Asia, and even Newfoundland and older Maine accents, the merger has not gone through and so pairs like pane-pain are distinct.
A distinction, with the
pane words pronounced with and the pain words pronounced with, survived in Norfolk English into the 20th century. Trudgill describes the disappearance of the distinction in Norfolk: "This disappearance was being effected by the gradual and variable transfer of lexical items from the set of to the set of as part of dedialectalisation process, the end-point of which will soon be the complete merger of the two lexical sets under — the completion of a slow process of lexical diffusion."
Walters reports the survival of the distinction in the Welsh English spoken in the Rhondda Valley, with in the
pane words and in the pain words.
In accents that preserve the distinction, the phoneme is usually represented by the spellings
ai, ay, ei and ey as in day, play, rain, pain, maid, rein, they etc. and the phoneme is usually represented by aCe as in pane, plane, lane, late etc. and sometimes by é'' and e as in re, café, Santa Fe etc.
IPA
adeaid
aleail
ateeight
balebail
badebayed
blareBlair
blazeBlaise
caneCain
cladeclayed
ClareClaire
batebait
Dalydaily
Danedeign
dazedays
e'erair
e'erheir
ereair
ereheir
fanefain
farefair
fazefays
flareflair
galeGail
gategait
gazegays
glaveglaive
gradegrayed
grazegrays
halehail
harehair
hazehays
hazeheys
ladelaid
lanelain
lazelays
mademaid
MaeMay
malemail
manemain
mazemaize
mazeMays
pagePaige
palepail
panepain
parepair
pearpair
phasefays
phrasefrays
planeplain
plateplait
Raeray
razeraise
razerays
razorraiser
reray
salesail
sanesain
saneseine
saneSeine
spadespayed
starestair
suedeswayed
taletail
theretheir
therethey're
tradetrayed
valevail
valeveil
vanevain
vanevein
wadeweighed
walewail
waleswails
Waleswails
wanewain
waneWayne
wastewaist
wavewaive
waverwaiver
whalewail

''Toe''–''tow'' merger

The toe–''tow merger is a merger of the Early Modern English vowels and 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. The traditional phonetic transcription for General American and earlier Received Pronunciation in the 20th century is, a diphthong. But in a few regional accents, including some in Northern England, East Anglia, South Wales and South Asia, the merger has not gone through, so that pairs like
toe and tow, moan and mown, groan and grown, sole and soul, throne and thrown are distinct.
In 19th 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 2002 investigation into the English of the Fens, young people in west Norfolk were found to be maintaining the distinction, with back or in the
toe set and central in the tow set, with the latter but not the former showing the influence of Estuary English.
Walters reports the survival of the distinction in the Welsh English spoken in the Rhondda Valley, with in the
toe words and in the tow words.
Reports of Maine English in the 1970s reported a similar
toad-towed distinction among older speakers, but was lost in subsequent generations.
In accents that preserve the distinction, the phoneme descended from Early Modern English is usually represented by the spellings
ou, and ow as in soul, dough, tow, know, though etc. or through L-vocalization as in bolt, cold, folk, roll etc., while that descended from Early Modern English is usually represented by oa, oe, or oCe as in boat, road, toe, doe, home, hose, go, tone etc.
IPA
Bobow
bodebowed
bornebourn
borneBourne
coaledcold
coarsecourse
do ''dough
doedough
dozedoughs
floeflow
foaledfold
forefour
forthfourth
frofrow
froefrow
frozefrows
groangrown
holedhold
moanmown
modemowed
Moemow
noknow
noseknows
Oowe
odeowed
ohowe
polepoll
porepour
roadrowed
roderowed
roerow
roleroll
roserows
shoneshewn
shoneshown
sosew
sosow
solesoul
soledsold
soledsouled
throethrow
thronethrown
toadtowed
toetow
toedtowed
toletoll

''Mare''–''mayor'' merger

The mare–''mayor merger occurs in British English and the PhiladelphiaBaltimore dialect, and among scattered other American English speakers. The process has bisyllabic pronounced with a centering diphthong as in in many words. Such varieties pronounce mayor as, homophonous with mare.
North American English accents with the merger allow it to affect also sequences without since some words with the sequence merge with, which is associated with /æ/ tensing before nasal consonants. The best-known examples are
mayonnaise, crayon, and Graham''.
IPA
bareBayer
flareflayer
flairflayer
gram, grammeGraham
lairlayer
maremayor
pairpayer
parepayer
pearpayer
prayerprayer
starestayer
swareswayer
swearswayer
therethey're

- merger

The - merger is a merger of the diphthongs and. It occurs for some speakers of West Country English and in the North of England.

''Pride''–''proud'' merger

The pride–''proud merger is a merger of the diphthongs and before voiced consonants into monophthongal occurring for some speakers of African American Vernacular English; making pride and proud, dine and down, find and found, etc. homophones. Some speakers with this merger may also have the rod–ride merger hence having a three–way merger of, and before voiced consonants, making pride, prod, and proud and find, found and fond'' homophones.
IPANotes
bibough
bibow
bidebowed
bightbout
bitebout
brinebrown
buybough-
buybow
bybough
bybow
byebough
byebow
chaichow
Clydecloud
dinedown
diredour
dynedown
filefoul
filefowl
findfound
finedfound
flightflout
Gilesjowls
hihow
highhow
hindhound
Iow
I'llowl
irehour
ireour
isleowl
Kaicow
Kylecowl
liarlour
licelouse
liedloud
lightlout
litelout
lyrelour
lyselouse
micemouse
mindmound
minedmound
nighnow
ninenoun
Nyenow
phialfoulWith vile-vial merger.
phialfowlWith vile-vial merger.
plyplow; plough
prideproud
priedproud-
priesprows
priseprows
prizeprows
pryprow
pyrepower
riderowed
rightrout
rightroute
rindround]
riserouse
riserows
riterout
riteroute
ryerow
ryesrouse
saisow
sighsow
signedsound]
siresour
sizesows-
slyslough
thythou
tietau
tighttout
tinetown
tritetrout
Tytau
vievow
whywowWith wine-whine merger.
wisewows
Y; wyewow

''Rod''–''ride'' merger

The rod–''ride merger is a merger of and occurring for some speakers of African American Vernacular English, in which rod and ride are merged as. Some other speakers may keep the contrast, so that rod is and ride is. Monophthongization of the PRICE vowel also occurs in Southern American English, however no vowel merger has been reported.
This is similar to an earlier sound change where Proto-Germanic *ai shifted to Old English
ā''.
IPANotes
aheye
ahI
baabuy
baaby
baabye
blotblight
bockbike
bodbide
botbight
botbite
boxbikes
conkine
cotkite
docdike
dockdike
domdime
Domdime
dondine
Dondine
fafie
farfire
gromgrime
hahigh
hockhike
hotheight
jargyre
jobgibe, jibe
knotknight
knotnight
lalie
lalye
locklike
lotlight, lite
loxlikes
mamy
marmire
mockmic
mockMike
mommime
mottemight
mottemite
nahnigh
nahNye
notknight
notnight
oddide
oddsides
oxIke's
papi
papie
parpyre
pockpike
podpied
plodplied
plotplight
poppipe
poxpikes
prodpride
prodpried
promprime
rahrye
rocReich
rockReich
rodride
ROMrime
ROMrhyme
rotright
rotrite
scrodscried
shahshy
shodshied
slotsleight
slotslight
sockpsych
sodside
sodsighed
sotsight
spaspy
sparspire
spotspite
stropstripe
swanswine
swapswipe
tatie
tartire, tyre
todtide
todtied
Toddtide
Toddtied
tomtime
tomthyme
Tomtime
Tomthyme
toptype
tottight
trodtried
trottrite
wadwhy'dWith wine-whine merger.
wadwide
wattwhiteWith wine-whine merger.
wattwight

Scottish vowel length rule

While the Scottish [vowel length rule|Scottish vowel length] rule affects most vowels, Wells analyses the split of the vowel as phonological rather than simply allophonic owing to its complexity. Some words such as fire break the pattern for some speakers. The split is present in Scottish English and can be traced back to the late 17th century in the Tyneside accent.
IPAIPANotes
tiedtideMorpheme boundary
sighedsideMorpheme boundary

Smoothing of

Smoothing of is a process that occurs in many varieties of British English where bisyllabic becomes the triphthong in certain words with. As a result, "scientific" is pronounced with three syllables and "science" is pronounced with one syllable.

Welsh distinctions

Some speakers of Welsh English make a distinction between the vowels of certain words in the and lexical sets, though the distinctions only affect a couple of words each.