Маъсул муҳаррир: Филология фанлари доктори, профессор: Г. Х. Боқиева Тақризчилар

Vowel Changes in MdE and Early MnE
Unstressed vowels
Levelling of unstressed vowels: all unstressed vowels were as a rule weakened and reduced to a neutral vowel, which was denoted by the letter –e. Thus, the infinitive suffix – an was reduced to –en: tellan – tellen, in a similar way: sunu – sune, sone. This weakening of unstressed vowels is closely connected with developments in declension and conjugation. From the 13^th c. onwards, some dialects showed certain vacillation in spelling unstressed vowels, which probably reflected peculiarities of pronunciation: askid, stonus.
Stressed Vowels
One of the most important sound changes of the Early MDE period of the loss of OE diphthongs and the growth of new diphthongs, with new qualitative and quantitative distinctions.
Monophthongization of OE Diphthongs
All OE diphthongs were monophthongized in ME.: eald – ald, healf –half, earm –arm (poor). But before ‘ld’ ‘ea’ yielded different results in different dialects. OE short ‘eo’ changed first into the vowel ‘ö’ spelt ‘eo’. In other dialects it changed into ‘e’ heorte – hörte-herte. (heart). OE long eo: changed into long closed e:, often spelt ‘ee’: deo:p – de:p, deep.
At the same time a new set of diphthongs developed from some sequences of vowels and consonants due to the vocalization of OE [j] and [γ], that is to their change into vowels: these sounds between after vowels changed into [i] and [u] and formed diphthongs together with the preceding vowel: OE dæg developed into day[dai]. These changes gave rise to two sets of diphthongs: with i-glides and u-glides {ei, ai, au, ou). In addition to the diphthongs developed from native sources, similar diphthongs – with i-and u-glides are found in some MdE loan words: boy, joy, pause, cause. The formation of new diphthongs was an important event in the history of the language. By that time the OE diphthongs had been contracted into monophthongs; the newly formed MdE diphthongs differed from the OE in structure: they had an open nucleus and a closer glide; they were arranged into a system consisting of two sets o (with i-glides and u-glides) but were not contrasted through quantity as long to short.