Phonological history of English consonant clusters

The phonological history of English includes various changes in the phonology of consonant clusters.

H-cluster reductions

The H-cluster reductions are various consonant reductions that have occurred in the history of English, involving consonant clusters beginning with that have lost the in some or all dialects.

Reductions of /hw/

The cluster has been subject to two kinds of reduction:

Reduction to before rounded vowels. This occurred with the word how in the Old English period, and with who, whom and whose in Middle English.
Reduction to, a development that has affected the speech of the great majority of English speakers, causing them to pronounce ⟨wh-⟩ the same as ⟨w-⟩. The distinction is maintained, however, in Scotland, most of Ireland, and some Southern American English.
Reduction of /hl/, /hr/ and /hn/

The Old English consonant clusters, and were reduced to,, and in Middle English. For example, Old English hlāf, hring and hnutu become loaf, ring and nut in Modern English.

Reduction of /hj/

In some dialects of English the cluster is reduced to, leading to pronunciations like for huge and for human, and making hew, hue, and Hugh homophones of ewe, yew, and you. This is sometimes considered a type of glide cluster reduction, but it is much less widespread than wh-reduction, and is generally stigmatized where it is found. Aside from accents with general H-dropping, in the United States this reduction is mostly found in accents of Philadelphia and New York City; it also occurs in Cork accents of Irish English. In other dialects of English, hew and yew remain distinct; however, the cluster of hew, human, etc. is often reduced from to just .

Y-cluster reductions

Y-cluster reductions are reductions of clusters ending with the palatal approximant, which is the sound of in yes, and is sometimes referred to as "yod", from the Hebrew letter yod, which has the sound. Many such clusters arose in dialects in which the falling diphthong became the rising diphthong. They were thus often found before the vowel, as in cube – which was in some cases modified to or before , as in cure, or weakened to or as in argument. They also occurred in words ending in -ion and -ious, such as nation and precious.
This change from to, which had occurred in London by the end of the 17th century, did not take place in all dialects. A few dialects, notably in Wales, as well as in some parts of northern England, New England, and the American South, still retain a diphthong where standard English has – these dialects therefore lack the clusters with and have not been subject to the reductions described here.
The diphthongs or are most commonly indicated by the spellings,, , and, as in feud, few, mute, cue and suit, while the historical monophthong is commonly indicated by the spellings and, as in moon and soup.

Yod-dropping

Yod-dropping is the elision of the from certain syllable-initial clusters of the type described above. Particular cases of yod-dropping may affect all or some of the dialects that have the relevant clusters.
The change of to in these positions produced some clusters which would have been difficult or impossible to pronounce, which led to what John Wells calls "early yod dropping" in which the was elided in the following environments:

After, for example chute, chew, juice
After, for example yew
After, for example rude
After stop+ clusters, for example blue

The previously mentioned accents that did not have the → change were not subject to this process. Thus, for example, in much Welsh English pairs like chews/''choose, yew/you and threw/through remain distinct: the first member of each pair has the diphthong, while the second member has :

chews, choose
yew, you
threw, through

Conversely, an initial does not appear in Welsh English before in words such as yeast and yield.
Many varieties of English have extended yod-dropping to the following environments if the is in the same syllable as the preceding consonant:

After, for example suit
After, for example lute
After, for example Zeus
After, for example enthuse

Yod-dropping in the above environments used to be considered nonstandard in England but now also occurs by educated RP-speakers. In General American, yod-dropping is found not only in the above environments but also after, and .
The lack of yod-dropping in those contexts has occasionally been held to be a shibboleth distinguishing Canadians from Americans. However, in a survey conducted in the Golden Horseshoe area of Southern Ontario in 1994, over 80% of respondents under the age of 40 pronounced student and news without yod.
Image:Iw-uw merger.svg|thumb|The areas marked in pink show where in the United States a distinction between in dew and in do may be made.
General American thus undergoes yod-dropping after all alveolar consonants. A few accents of American English, such as working-class Southern American English, however, preserve the distinction in pairs like do/dew because, like in the Welsh English dialects discussed above, they retain a diphthong in words in which RP has :,, etc.
However, in words like annual, menu, volume, Matthew, continue, etc., with a syllable break before the, there is no yod-dropping. The same applies accordingly to British and other accents; the yod is often dropped after initial, for example, but it is not dropped in words like volume or value.
Additionally, there is no in British pronunciations of coupon and Pulitzer, and respectively, but many American speakers keep the yod, realizing them as and, although Pulitzer with the pew sound is widely incorrect.
In New Zealand and to some extent Australian English, debut is mainly pronounced without the yod as.
Yod-dropping after,, and was also a traditional feature of Cockney speech, which continues to be the case after, but now, after and, yod-coalescence is now more common.
Some East Anglian accents such as Norfolk dialect extend yod-dropping not only to the position after, or but also to the position after nonalveolar consonants as well: pairs like beauty/booty, mute/moot, cute/coot'' can then be homophonous. A well-known series of British television advertisements beginning in the 1980s featured Bernard Matthews, who was from Norfolk and described his turkeys as "bootiful". Such accents pronounce a in words like "use", "unit", etc. only if there is no consonant before the.

		IPA	Notes
brewed	brood		-
brume	broom		-
chews	choose		-
chute	shoot		-
drupe	droop		-
rheum	room		-
rude	rood		-
rue	roo		-
ruse	roos		-
threw	through		-
yew	you		-
yule	you'll		-

		IPA	Notes
adieu	ado		-
dew	do		-
Dewar	doer		-
due	do		-
dune	Doon		-
knew	nu		-
new	nu		-
tune	toon		-

Yod-coalescence

Yod-coalescence is a process that fuses the clusters into the sibilants respectively. The first two are examples of affrication.
Unlike yod-dropping, yod-coalescence frequently occurs with clusters that would be considered to span a syllable boundary and so commonly occurs before unstressed syllables. For example, in educate, the cluster would not usually be subject to yod-dropping in General American, as the is assigned to the previous syllable, but it commonly coalesces to. Here are a few examples of yod-coalescence universal in all English dialects:

in most words ending -ture, such as nature
in soldier
in words ending with -ssure such as pressure
in words ending vowel+sure such as measure

In some other words, the coalesced pronunciation is common in English dialects around the world, but an older non-coalesced form still exists among some speakers of standard British English:

educate
azure
issue , the intermediate form being also common

Coalescence can even occur across word boundaries, as in the colloquial "gotcha" and "whatcha" .
In certain English accents, yod-coalescence also occurs in stressed syllables, as in tune and dune. That occurs in Australian, Cockney, Estuary English, Zimbabwean English, some speakers of Hiberno-English, Newfoundland English, South African English, and to a certain extent in New Zealand English, RP, many speakers in Scottish English, and even some varieties of English in Asia, like Philippine English. That results in pronunciations such as the following:

dew/due
tune

In certain varieties such as Australian, Ugandan, and some RP, stressed can also coalesce:

resume
assume

That can lead to additional homophony; for instance, dew and due come to be pronounced the same as Jew.
Yod-coalescence has traditionally been resisted in Received Pronunciation. It has certainly become established in words of the first group listed above, but it is not yet universal in those of the second group, and it does not generally occur in those of the third group.

		IPA	Notes
deuce	juice		-
dew	Jew		-
dewed	Jude		-
dual	jewel		-
due	Jew		-
duel	jewel		-
duke	juke		-
duly	Julie		-
dune	June		-
duty	Judy		With intervocalic alveolar flapping.
sue	shoe		-
sue	shoo		-
suit	chute		-
suit	shoot		-
'tude	chewed		-

See also

List of yod-dropping and coalescence homophones on Wiktionary.