Stressed vowel systems in Southern Russian as a source for linguistic reconstruction.

The paper is focussing on the synchronic and diachronic study of stressed vowel systems of the different South Russian dialects. A vowel system which consists of seven phonemes can exist only with diphthongs [ı͡e] and [u͡ o], which are the realization of the phonemes /ѣ/ and /ω/ respectively. These diphthongs manifest a completely parallel structure. Firstly, it explains the nature of the diphthongal /ѣ/ in the Old Russian language; secondly, it supports the view that the phoneme /ω/ appears to be a correlate of the phoneme /ѣ/, which is a result of the trend towards the symmetrisation of the Old Russian language system. In the archaic South Russian dialects phoneme /у/, /о/ and /е/ may be realised by lowered sounds [u̞], [ɔ], [ɛ] and phoneme /a/ — by more front sound [а̘]. The fixation of the sounds [u̞], [ɔ], [ɛ], [а̘] in the dialect with the vowel system of five phonemes can be used as an evidence of the archaism of this system and the presence in it not so long ago the opposition of /ω/ ~ /о/ and /ѣ/ ~ /е/.