Vowels in the unstressed position

All vowels in the unstressed position underwent a qualitative change and became the vowel of the type of [ə] or [e] unstressed. This phonetic change had a far-reaching effect upon the system of the grammatical endings of the English words which now due to the process of reduction became homonymous. For example:

- forms of strong verbs

Old English writan – wrāt – writon – written

with the suffixes –an,-on,-en different only in the vowel component became homonymous in middle English:

written – wrōt – written

- forms of nouns

Old English Nominative Plural a-stem fiscas

Genitive Singular fisces

Middle English for both the forms is fisces;

Or

Old English Dative Singular fisce

Genitive Plural fisca

Middle English form in both cases is fisce.

Vowels under stress

Qualitative changes

- changes of monophthongs

Old English Middle English

ē [ē] tēþ teeth

ō [ō] tōþ tooth

ū ūt out

ī tīma time

out of the seven principal Old English short monophthongs: a,e,o,I,u,æ,y – two changed their quality in Middle English thus [æ] became [a] and [y] became [i], the rest of the monophthongs remaining unchanged, for example:

Old English Middle English

þæt that

wæs was

first first

but:

tellan tellen

hors hors

singan singen

putan putten

- changes of diphthongs

all Old English diphthongs were contracted (became monothongs) at the end of the old English period.

Diphthongs

Old English Middle English

ēo > ē dēop deep

ēa > ē brēad bread

eo > e seofon seven

ea > a eald ald

But instead of the former diphthongs that had undergone contraction at the end of the Old English period there appeared in Middle English new diphthongs. The new diphthongs. The new diphthongs sprang into being due to the vocalization of the consonant [j] after the front vowels [e] or [æ] or due to the vocalization of the consonant [γ] or the semi-vowel [w] after the back vowels [o] and [a]. For instance:

Old English Middle English

dæз > dæз > dai

weз > weз > wei

grēз > greз > grei

draзan > drawen > drauen

āзan > 8wen > ouen

boзa > bowe > boue

Thus in Middle English there appeared four new diphthongs: [ai], [ei], [au], [ou].

Quantative changes

Besides qualitative changes mentioned above vowels under stress underwent certain changes in quantity.

- lengthening of vowels