Phonological history of English diphthongs

Template:Short description Template:English phonology topics Template:IPA notice 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 (both elements at the same height) with the second element further back than the first. The set of diphthongs that occurred depended on dialect (and their exact pronunciation is in any case uncertain). Typical diphthongs are considered to have been as follows:

• high, fully backing, , spelt Template:Angbr (found in Anglian dialects, but merged into in Late West Saxon)
• high, narrower, possibly , spelt Template:Angbr (found in Late West Saxon)
• mid, , spelt Template:Angbr
• low, , spelt Template:Angbr

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: Template:Angbr, Template:Angbr, Template:Angbr, Template:Angbr.

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 (usually from an earlier ) or the labio-velar approximant (sometimes from an earlier voiced velar fricative ), when they followed a vowel. For example:

• OE dæg ("day") and weg ("way") (where the had been palatalized to ) became and
• OE clawu ("claw") and lagu ("law") became and

Diphthongs also arose as a result of vowel breaking before (which had allophones and in this position – for the subsequent disappearance of these sounds, see h-loss). For example:

• OE streht ("straight") became
• OE þoht ("thought") 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 (borrowings from French) 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 (around the 1800s) 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 (the product of the vein–vain merger)
• as in joy, noise, royal, coy

and four ended in :

• as in view, new, due, use, lute, suit, adieu (the product of a merger of earlier and , and incorporating French loans that originally had )
• 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 (show), 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.
• (from the vein–vain merger) became monophthongized and merged with the of words like name (which before the Great Vowel Shift had been long ). 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, join–line in Pope, child–spoil'd in Swift, toils–smiles in Dryden. 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 (the products of the pane–pain and toe–tow mergers) 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 (see English-language vowel changes before historic ). They occur in words like near, square and cure.

Present-day RP is thus normally analyzed as having eight diphthongs: the five closing diphthongs , , , , (of face, goat, price, mouth and choice) and the three centering diphthongs , , . General American does not have the centering diphthongs (at least, not as independent phonemes). For more information, see English phonology (vowels).

Variation in present-day English

Coil–curl merger

The coil–curl or oil–earl 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.

Homophonous pairs

		IPA
aisle	oil
ally	alloy
bile	boil
buy, by, bye, buy	boy, buoy
divide	devoid
dried	droid
file	foil
fire	foyer
grind	groined
guy	goy
heist	hoist
hi, high	hoy
I	oi, oy
I'll, isle	oil
imply	employ
Jain	join
Kai	coy, koi
kine	coin
Kyle	coil
liar	lawyer
lied	Lloyd
line	loin
Lyle	loyal
lyre	lawyer
mile	moil
nighs	noise
Nile	noil
pie	poi
pies	poise
pint	point
ply	ploy
psi	soy
quite	quoit
ride	roid
rile	roil
rile	royal
rye	Roy
sigh	soy
sire	sawyer
sire	soya
Thai, tie	toy
tide	toyed
tile	toil
try	Troy
vice	voice
vied	void
wry	Roy

Long mid mergers

The earliest stage of Early Modern English had a contrast between the long mid monophthongs (as in pane and toe respectively) and the diphthongs (as in pain and tow respectively). In the vast majority of Modern English accents these have been merged, so that the pairs pane–pain and toe–tow 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 (at least not completely) 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 (a few speakers even today maintain a vestigial and variable distinction) the complete merger of the two lexical sets under — 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 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.

Homophonous pairs

		IPA
ade	aid
ale	ail
ate	eight
bale	bail
bade	bayed
blare	Blair
blaze	Blaise
cane	Cain
clade	clayed
Clare	Claire
bate	bait
Daly	daily
Dane	deign
daze	days
e'er	air
e'er	heir
ere	air
ere	heir
fane	fain
fare	fair
faze	fays
flare	flair
gale	Gail
gate	gait
gaze	gays
glave	glaive
grade	grayed
graze	grays
hale	hail
hare	hair
haze	hays
haze	heys
lade	laid
lane	lain
laze	lays
made	maid
Mae	May
male	mail
mane	main
maze	maize
maze	Mays
page	Paige
pale	pail
pane	pain
pare	pair
pear	pair
phase	fays
phrase	frays
plane	plain
plate	plait
Rae	ray
raze	raise
raze	rays
razor	raiser
re	ray
sale	sail
sane	sain
sane	seine
sane	Seine
spade	spayed
stare	stair
suede	swayed
tale	tail
there	their
there	they're
trade	trayed
vale	vail
vale	veil
vane	vain
vane	vein
wade	weighed
wale	wail
wales	wails
Wales	wails
wane	wain
wane	Wayne
waste	waist
wave	waive
waver	waiver
whale	wail

Toe–tow merger

The toe–tow merger is a merger of the Early Modern English vowels (as in toe) and (as in tow) that occurs in most dialects of English. (The vowels in Middle English and at the beginning of the Early Modern English period were and respectively, and they shifted in the second phase of the Great Vowel Shift.)

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 (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 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.

Homophonous pairs

		IPA
Bo	bow
bode	bowed
borne	bourn(e)
borne	Bourne
coaled	cold
coarse	course
do (note)	dough
doe	dough
doze	doughs
floe	flow
foaled	fold
fore	four
forth	fourth
fro	frow
froe	frow
froze	frows
groan	grown
holed	hold
moan	mown
mode	mowed
Moe	mow
no	know
nose	knows
O	owe
ode	owed
oh	owe
pole	poll
pore	pour
road	rowed
rode	rowed
roe	row
role	roll
rose	rows
shone	shewn
shone	shown
so	sew
so	sow
sole	soul
soled	sold
soled	souled
throe	throw
throne	thrown
toad	towed
toe	tow
toed	towed
tole	toll

Mare–mayor merger

The mare–mayor merger occurs in British English and the Philadelphia—Baltimore 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 (, a homophone of gram).

Homophonous pairs

		IPA
bare	Bayer
flare	flayer
flair	flayer
gram, gramme	Graham
lair	layer
mare	mayor
pair	payer
pare	payer
pear	payer
prayer	prayer
stare	stayer
sware	swayer
swear	swayer
there	they're

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.

Homophonous pairs

		IPA	Notes
bi	bough
bi	bow
bide	bowed
bight	bout
bite	bout
brine	brown
buy	bough
buy	bow
by	bough
by	bow
bye	bough
bye	bow
chai	chow
Clyde	cloud
dine	down
dire	dour
dyne	down
file	foul
file	fowl
find	found
fined	found
flight	flout
Giles	jowls
hi	how
high	how
hind	hound
I	ow
I'll	owl
ire	hour
ire	our
isle	owl
Kai	cow
Kyle	cowl
liar	lour
lice	louse
lied	loud
light	lout
lite	lout
lyre	lour
lyse	louse
mice	mouse
mind	mound
mined	mound
nigh	now
nine	noun
Nye	now
phial	foul		With vile-vial merger.
phial	fowl		With vile-vial merger.
ply	plow; plough
pride	proud
pried	proud
pries	prows
prise	prows
prize	prows
pry	prow
pyre	power
ride	rowed
right	rout
right	route
rind	round	]
rise	rouse
rise	rows
rite	rout
rite	route
rye	row
ryes	rouse
sai	sow
sigh	sow
signed	sound	]
sire	sour
size	sows
sly	slough
thy	thou
tie	tau
tight	tout
tine	town
trite	trout
Ty	tau
vie	vow
why	wow		With wine-whine merger.
wise	wows
Y; wye	wow

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 .

This is similar to an earlier sound change where Proto-Germanic *ai shifted to Old English ā.

Homophonous pairs

		IPA	Notes
ah	eye
ah	I
baa	buy
baa	by
baa	bye
blot	blight
bock	bike
bod	bide
bot	bight
bot	bite
box	bikes
con	kine
cot	kite
doc	dike
dock	dike
dom	dime
Dom	dime
don	dine
Don	dine
fa	fie
far	fire
grom	grime
ha	high
hock	hike
hot	height
jar	gyre
job	gibe, jibe
knot	knight
knot	night
la	lie
la	lye
lock	like
lot	light, lite
lox	likes
ma	my
mar	mire
mock	mic
mock	Mike
mom	mime
motte	might
motte	mite
nah	nigh
nah	Nye
not	knight
not	night
odd	ide
odds	ides
ox	Ike's
pa	pi
pa	pie
par	pyre
pock	pike
pod	pied
plod	plied
plot	plight
pop	pipe
pox	pikes
prod	pride
prod	pried
prom	prime
rah	rye
roc	Reich
rock	Reich
rod	ride
ROM	rime
ROM	rhyme
rot	right
rot	rite
scrod	scried
shah	shy
shod	shied
slot	sleight
slot	slight
sock	psych
sod	side
sod	sighed
sot	sight
spa	spy
spar	spire
spot	spite
strop	stripe
swan	swine
swap	swipe
ta	tie
tar	tire, tyre
tod	tide
tod	tied
Todd	tide
Todd	tied
tom	time
tom	thyme
Tom	time
Tom	thyme
top	type
tot	tight
trod	tried
trot	trite
wad	why'd		With wine-whine merger.
wad	wide
watt	white		With wine-whine merger.
watt	wight

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.

See also

• Phonological history of English
• Phonological history of English vowels
• Trisyllabic laxing
• Great Vowel Shift