The OE close labialized vowels [y] and [y:] disappeared in Early ME. In Early ME the dialectal differences grew. In some areas OE [y], [y:] developed into [e], [e:], in others they changed to [i], [i:], in the South-West and in the west Midlands the two vowels were for some time preserved as [y], [y:] but later were moved backward and merged with [u], [u:]. OE fyllan – ME Kentish fellen [], ME West Midland and South Western fullen [], ME east Midland and Northern fillen [] (NE fill). In early ME the long OE [a:] was narrowed to []. This was an early instance of the growing tendency of all long monophthongs to become closer; the tendency was intensified in Late ME when all long vowels changed in that direction. [a:] became [] in all the dialects except the Northern group. ME Northern stan(e) [], ME other dialects stoon, stone [], (NE stone). The resulting ME [] must have been a more open vowel than the long [o:] inherited from OE. The two phonemes [] and [o:] were well distinguished in ME, though no distinction was made in spelling: o, and double o were used for both sounds. The short OE [] was replaced in ME by the back vowel [a]. In OE [] was either a separate phoneme or one of a group of allophones distinguished in writing []. All these sounds were reflected in ME as [a], except the nasalized [a] which became [o] in the West Midlands. ME t hat [], NE that, ME blak [] NE black, ME West Midland lond [], ME other dialects land []. Most of the modern words going back to the OE prototypes with the vowel [a] have [a], e.g. NE man, sand, and, which means that they came from any dialect except west Midland; some words, however, especially those ending in [], should be traced to the West Midlands, e.g. long, song, strong, from, bond.
