Phonological history of Old English

The Anglo-Frisian languages underwent a sound change in their development from Proto-West-Germanic by which ⟨ā⟩ [ɑː], unless followed by /n, m/ or nasalized, was fronted to ⟨ǣ⟩ [æː].

slǣpan, sċēap (< Proto-West-Germanic *slāpąn, *skāpă < Proto-Germanic *slēpaną, skēpą) versus Anglian slēpan, sċēp.

The Modern English descendants sleep and sheep reflect the Anglian vowel; the West Saxon words would have developed to *sleap, *sheap.

[2] However, borrowings such as Old English strǣt from Latin strāta (via) and the backing to ō before nasals are much easier to explain under the assumption of a common West Germanic stage *ā. Proto-Germanic /ai/ was monophthongized (smoothed) to /aː/ ([ɑː]).

However, the infinitive ġefan retains its back vowel due to a-restoration (see the explanation given in that section for the similar case of faren vs. faran).

There are analyses that treat all of these diphthongs as ending in a schwa sound [ə]; i.e. ēa, ēo, īo = [æə], [eə], [iə].

Examples: Note that in some dialects /æ/ was backed (retracted) to /a/ ([ɑ]) rather than broken, when occurring in the circumstances described above that would normally trigger breaking.

Howell proposes instead that prior to Old English, *x was originally weakened to [h] in all positions (which he argues is supported by its loss between vowels), and that this [h] became strengthened to [x] in the syllable coda later on, perhaps at the time when it merged phonemically with the devoiced outcome of former [ɣ].

(Note: The situation is complicated somewhat by a later change called second fronting, but this did not affect the standard West Saxon dialect of Old English.)

Because strong masculine and neuter nouns have back vowels in plural endings, alternations with /æ/ in the singular vs. /a/ in the plural are common in this noun class: A-restoration occurred before the *ō of the weak verb suffix *-ōj-, although this surfaces in Old English as the front vowel i, as in macian "to make" < **makōjan-.

This order is necessary to account for words like slēan "to slay" (pronounced /slæːɑn/) from original *slahan: /ˈslahan/ > /ˈslæhan/ (a-fronting) > /ˈslæɑhɑn/ (breaking; inhibits a-restoration) > /ˈslæɑ.ɑn/ (h-loss) > /slæːɑn/ (vowel coalescence, compensatory lengthening).

Basically: Note that the key difference is in steps 3 and 4, where nasalised ą is unaffected by a-fronting even though the sequence an is in fact affected, since it occurs in an unstressed syllable.

The presence of back a in the stem of both forms is not directly explainable by sound change, and appears to have been the result of simple analogical levelling.

Nor did it occur in cyning ("king"), cemban ("to comb") or gēs ("geese"), where the front vowels /y, e, eː/ developed from earlier /u, a, oː/ due to i-mutation.

The sounds /k~tʃ/ and /ɡ~j/ had almost certainly split into distinct phonemes by Late West Saxon, the dialect in which the majority of Old English documents are written.

This is suggested by such near-minimal pairs as drincan [ˈdriŋkɑn] ("drink") vs. drenċan [ˈdrentʃɑn] ("drench"), and gēs [ɡeːs] ("geese") vs. ġē [jeː] ("you").

In the standard modernised orthography (as used here), the velar and palatal variants are distinguished with a diacritic: ⟨c⟩ stands for /k/, ⟨ċ⟩ for /tʃ/, ⟨g⟩ for [ɡ] and [ɣ], and ⟨ġ⟩ for [j] and [dʒ].

Loanwords from Old Norse typically do not display any palatalisation, showing that at the time they were borrowed the palatal–velar distinction was no longer allophonic and the two sets were now separate phonemes.

Similarly, give, an unpalatalised Norse borrowing, existed alongside (and eventually displaced) the regularly palatalised yive.

[14] Second fronting took place only in a relatively small section of the area (English Midlands) where the Mercian dialect was spoken.

)", þrescenne "to thresh", onbran "set fire to (past)", īsern "iron", ren- "house", þridda "third"; briddes "birds" in Chaucer).

For example, This loss affected the plural of root nouns, e.g. PrePG *pōdes > PG *fōtiz > *fø̄ti > OE fēt "feet (nom.)".

Paradigm split also occurred medially as a result of high-vowel loss, e.g. in the past tense forms of Class I weak forms: Normally, syncopation (i.e. vowel loss) does not occur in closed syllables, e.g. Englisċe "English", ǣresta "earliest", sċēawunge "a showing, inspection" (each word with an inflected ending following it).

Some details are different, as the form kunni with retained -i is found in Old Saxon, Old Dutch and Old High German (but note Old Frisian kenn, kin).

A number of restrictions governed whether back mutation took place: In the Anglian (i.e. Mercian and Northumbrian) dialects of Old English, a process called smoothing undid many of the effects of breaking.

Examples: Palatal umlaut is a process whereby short e, eo, io appear as i (occasionally ie) before final ht, hs, hþ.

In the late 8th or early 9th century, short stressed vowels were lengthened before certain groups of consonants: ld, mb, nd, ng, rd, rl, rn, rs+vowel.

Mercian constituted the middle section of the country, divided from the southern dialects by the Thames and from Northumbrian by the Humber and Mersey rivers.

The distinguishing feature of Northumbrian, the lack of palatalisation of velars, is still evident in doublets between Scots and Modern English such as kirk / "church", brig / "bridge", kist / "chest", yeuk / "itch" (OE ġyċċan < PGmc jukjaną).

Its main source is late Middle English /au/, which come from various sources: Old English ⟨aw⟩ and ⟨ag⟩ ("claw" < clawu, "law" < lagu); diphthongisation before /h/ ("sought" < sōhte, "taught" < tāhte, "daughter" < dohtor); borrowings from Latin and French ("fawn" < Old French faune, "Paul" < Latin Paulus).