Lecture Word Stock of Middle English Period. Phonetic peculiarities of Middle English

Lengthening. In the 13th century short vowels were lengthened in open 
syllables. This was another item of the development which deprived quantity 
(length/ shortness) of its status as a phonemic feature. 
Lengthening affected the short vowels a, e, o. In the Northern dialects it 
started in the 12th century, and in the 13th it spread all over England. The long 
vowels ë and ö which resulted from this change were open vowels; thus, the ë 
from e coincided with ë from æ and ëä; the öfrom o with ö from ä (in Midland 
and Southern dialects). For example: cäru> care ‘care’, talu> täle ‘tale’, 
macian> mäken ’make’, węrian> wëren ‘wear’, stelan> stëlen ‘steal’, specan> 
spëken ‘speak’, hopian> höpen ‘hope’, smocian> smöken ‘smoke’. 
The narrow vowels i and u remained as a rule unaffected by this change, 
and thus the difference between short i and long and also that between short u andü retained its 
quality as a phonemically relevant feature. In a few words, 
however, the narrow vowels were also lengthened in open syllables, and the 
narrow vowels were widened in the process, thus, i>ë, u>ö, as in wikes> wëkes 
‘weeks’, yfel> ifel> ëvel ‘evil’, dures> döres ‘doors’. This change mainly 
occurred in the Northern dialect; it partly also affected the East Midland dialect. 
Development of other vowels. OE e, ë, i, ï, o were unchanged in ME: cf. 
bettre, tellan> tellen , ‘tell’, cëpan> këpen ‘keep’, tëp> tëth ‘teeth’, sin3an> 
singen ‘sing’, wille> will, writan> writen ‘write’, tima> time ‘time’, folc> folk 
‘folk’. OE long ö mostly remained unchanged: föt ‘foot’, böc> bök ‘book’. 
However, in the Northern dialects the long ö began in the 13th century to developinto {ö>ü}. 
This vowel rhymes with French {ü}; it is denoted by the letter u orby the digraph ui, as in gud 
‘good’, buk ‘book’, fut ‘foot’. OE short u and long ü remained unchanged in ME: sunu> sone 
{sun1}’son, hü> how {hü}, tün> town {tu:n}, üt> out {u:t}.