Phonological history of English open back vowels


The phonology of the open back vowels of the English language has undergone changes both overall and with regional variations, through Old and Middle English to the present. The sounds heard in modern English were significantly influenced by the Great Vowel Shift, as well as more recent developments such as the cot–caught merger.

Overview

Old and Middle English

In the Old English vowel system, the vowels in the open back area were unrounded:. There were also rounded back vowels of mid-height:. The corresponding spellings were and, with the length distinctions not normally marked; in modern editions of Old English texts, the long vowels are often written,.
As the Old English system developed into that of Middle English, the OE short vowel merged with the fronted to become a more central ME. Meanwhile, the OE long vowel was rounded and raised to ME. OE short remained relatively unchanged, becoming a short ME vowel regarded as, while OE long became ME . Alternative developments were also possible; see English historical vowel correspondences for details.
Later, ME open syllable lengthening caused the short vowel to be normally changed to in open syllables. Remaining instances of the short vowel also tended to become lower. Hence in Late Middle English the following open back vowels were present, distinguished by length:
By 1600, the following changes had occurred:
There were thus two open back monophthongs:
and one open back diphthong:
By 1700, the following further developments had taken place:
That left the standard form of the language with three open back vowels:
From the 18th century on, the following changes have occurred:
This leaves RP with three back vowels:
and General American with two:
Lexical setExample wordsChangeGenAm phonemesMinimal pairsIPAChangeCot-Caught merger dialects
ah, father, spaFather-bother
merger
cot, collar, stock,
wok, chock, Don
,,,
,,
Cot–caught
merger
,,,
,,
bother, lot, waspFather-bother
merger
cot, collar, stock,
wok, chock, Don
,,,
,,
Cot–caught
merger
,,,
,,
boss, cloth, dog, offCloth-thought
merger
caught, caller, stalk,
walk, chalk, dawn
,,,
,,
Cot–caught
merger
,,,
,,
all, thought, flauntCloth-thought
merger
caught, caller, stalk,
walk, chalk, dawn
,,,
,,
Cot–caught
merger
,,,
,,

Unrounded

In a few varieties of English, the vowel in lot is unrounded, pronounced toward . This is found in the following dialects:
Linguists disagree as to whether the unrounding of the lot vowel occurred independently in North America or was imported from certain types of speech current in Britain at that time.
In such accents, lot typically is pronounced as, therefore being kept distinct from the vowel in palm, pronounced or. However, the major exception to this is North American English, where the vowel is lengthened to merge with the vowel in palm, as described below. This merger is called the merger or more commonly the father–bother merger.

''Father–bother'' merger

The father–bother merger is unrounded lot taken a step further. On top of being unrounded, the length distinction between the vowel in lot and bother and the vowel in palm and father is lost, so that the two groups merge.
Examples of possible homophones resulting from the merger include Khan and con as well as Saab and sob.
Out of North American dialects that have unrounded lot, the only notable exception to the merger is New York City English, where the opposition with the -type vowel is somewhat tenuous.
While the accents in northeastern New England, such as the Boston accent, also remain unmerged, lot remains rounded and merges instead with cloth and thought, though the outcome of that is still a longish free vowel that is heard as thought by British speakers.

split

The split is the result of a late 17th-century sound change that lengthened to before voiceless fricatives, and also before in the word gone. It was ultimately raised and merged with of words like thought, although in some accents that vowel is actually open. The sound change is most consistent in the last syllable of a word, and much less so elsewhere. Some words that entered the language later, especially when used more in writing than speech, are exempt from the lengthening, e.g. joss and Goth with the short vowel. Similar changes took place in words with ; see trap–bath split and /æ/-tensing.
The cot–caught merger, discussed below, has removed the distinction in some dialects.
As a result of the lengthening and raising, in the above-mentioned accents cross rhymes with sauce, and soft and cloth also have the vowel. Accents affected by this change include American English and, originally, RP, although today words of this group almost always have short in RP. The split still exists in some older RP speakers, including Queen Elizabeth II.
The lengthening and raising generally happened before the fricatives, and. In American English the raising was extended to the environment before and, and in a few words before as well, giving pronunciations like for long, for dog and for chocolate.
In the varieties of American English that have the lot–cloth split, the lot vowel is usually symbolized as, often called the "short o", and the cloth vowel as, often called the "open o". The actual pronunciation of these vowels may vary somewhat from the symbol used to denote them; e.g. is often pronounced closer to an open back rounded vowel, and is sometimes fronted to an open central vowel. Some words vary as to which vowel they have. For example, words that end in -og like frog, hog, fog, log, bog etc. have rather than in some accents.
There are also significant complexities in the pronunciation of written o occurring before one of the triggering phonemes in a non-final syllable. However, the use of the open o as opposed to the short o is largely predictable. Just like with /æ/-tensing and the trap–bath split, there seems to be an open-syllable constraint. Namely, the change did not affect words with /ɑ/ in open syllables unless they were closely derived from words with in close syllables. Hence occurs in crossing, crosser, crosses because it occurs in cross; likewise in longing, longer, longest because it occurs in long. However, possible, jostle, impostor, profit, Gothic, bongo, Congo, and boggle all have. However, there are still exceptions in words like Boston and foster. A further list of words is mentioned in the table below:
SetRounded Unrounded
all words in this set
loss, boss, etc.possible, jostle
Boston, foster, lost, etc.roster
long, longest, etc.bongo, Congo

Some words may vary depending on the speaker like. Meanwhile, other words vary by region. For example, in the Mid-Atlantic U.S. dialect, most famously spoken in metropolitan Philadelphia and Baltimore, the single word on has the same vowel as dawn, but not the same vowel as don etc.. Labov et al. regard this phenomenon as occurring not just in the Mid-Atlantic region, but in all regions south of a geographic boundary that they identify as the ON line, which is significant because it distinguishes most varieties of Northern American English from most varieties of Midland and Southern American English.

''Cot–caught'' merger

The cotcaught merger is a phonemic merger occurring in many English accents, where the vowel sound in words like cot, nod, and stock, has merged with that of caught, gnawed, and stalk. For example, with the merger, cot and caught become perfect homophones.

Other changes

split

In some London accents of English, the vowel in words such as thought, force, and north, which merged earlier on in these varieties of English, undergoes a conditional split based on syllable structure: closed syllables have a higher vowel quality such as , and open syllables have a lower vowel quality or a centering diphthong.
Originally-open syllables with an inflectional suffix retain the lower vowel quality, creating minimal pairs such as bored vs. board.
In broad Geordie, some words have instead of the standard. Those are the traditional dialect forms which are being replaced with the standard. is therefore not necessarily a distinct phoneme in the vowel system of Geordie, also because it occurs as an allophone of before voiced consonants.

merger

The merger is a merger of the English vowels and . It occurs in certain non-rhotic varieties of British English, such as Bradford English and Geordie. It has also been reported as a possibility in some Northern Welsh accents.
It is more accurately called the merger.
IPA
aweO
aweoh
aweowe
awnown
boarbeau
boarbow
borebeau
borebow
caughtcoat
courtcoat
doordoe
doordough
doorsdoes
doorsdoughs
doorsdoze
haulhole
lawlow
lawnloan
lawnlone
naughtnote
norknow
norno
noughtnote
oarO
oaroh
oarowe
orO
oroh
orowe
oughtoat
Paulpole, Pole
Paulpoll
roarrow
roarsrose
roarsrows
sawsew
sawso
sawsow
soarsew
soarso
soarsow
soresew
soreso
soresow
toretoe
toretow

Distribution of /ɑː/

The distribution of the vowel transcribed with in broad IPA varies greatly among dialects. It corresponds to,, and and even in other dialects:
In many Scottish dialects, there is just one unrounded open vowel, usually transcribed with. Those dialects usually do not differentiate from and use for both.

Fronted /oʊ/

In many dialects of English, the vowel has undergone fronting. The exact phonetic value varies. Dialects with the fronted include Received Pronunciation; Southern, Midland, and Mid-Atlantic American English; and Australian English. This fronting does not generally occur before, a relatively retracted consonant.

Table