There is no diphthongization
in central and western Saaremaa.
The process is discussed in some detail in Collins (1983a) and numerous examples of diphthongization
and centralization of final high vowels can be found in Collins (1983b).
Second, although a two-phase GVS is widely accepted (one, raising of /e: o:/ and diphthongization
of /i: u:/ completed by the early 16th century and two, raising of /[epsilon]: [TEXT NOT REPRODUCIBLE IN ASCII.
Serjeantson thinks that, in this respect, "the diphthongization
of before z and h does not seem to be confined to the dialects of any specific area" (1927b: 198).
In the section on the palatal diphthongization
of Germanic ae (p.
147) argues that "in WS at least, diphthongization
normally did take place when that was a method for resolving hiatus".
Where ME o was fronted to e, the diphthongization of u was inhibited (1994: 234, fn.
The only segment of these changes that looks like it might be properly called a "shift" is the first segment, which traditionally is taken to be diphthongization of [i:] and [u:].
Of particular interest are the diphthongs that have been formed as a result of the diphthongization of long /a/ and /o/.
The present paper aims to address this gap in our knowledge and focus on the acoustic study of the six diphthongs which have formed due to the diphthongization of long open and mid vowels.
The lengthening of stressed i/I, which apparently had a compensatory character following the loss of final <ch>, must have taken place in the latter half of the 15th century, thus creating a proper input to diphthongization
by the Great Vowel Shift.