The Belarusian-Ukrainian border region is characterized by a diphthongal pronunciation of the sounds о and е in stressed positions, such as: muost, vuosk, valyé, miahíe, dziatykié. This topic was addressed by A. Matach in the pages of the Kaunas magazine “Kryvič” (Diphthongs уо, (юо=іуо), ыэ, (іе), in: “Kryvič”, No. 8, Kaunas 1924, pp. 104-105).
“The first diphthong – уо – is widespread in the language throughout Kryvi (Belarus) and is pronounced in names and pronouns in the middle of words under stress, but it should not always be there where the Russian о (ё) is written, because, for example, in the words корова, солома, молоко, море, слёзы, etc., the Kryvian о (ё) sounds the same as in the Russian language (literary). The rule that would clearly define when to pronounce уо (юо=іуо) in words and when there is no pure о (ё) is known only to a native Kryvian or to a foreigner who learned our language not from a book but by ear. A Litvin would not be mistaken in this case, as in the Lithuanian language the diphthong уо is pronounced the same as in ours.
The second diphthong - ыэ (іе) - is always pronounced under stress in the endings of names and pronouns in the nominative and accusative cases of the plural, for example: “Паныэ і маскаліе прапілі свае дварыэ і апаражнілі капшукіе ад грошай.” This diphthong is widespread in the language of the Kryvian population, starting from Pruzhany and further north and east through Hrodna region, and touching upon Novogrudok, Nesvizh, and Slutsk, it passes through a narrow belt through Chernigov region, into eastern Smolensk region and is manifested in Velyzhsky and Vialikalyutsky districts” (ibid., p. 104).
A. Matach believes that if the diphthong уо is transmitted as о, it would also be advisable to transmit the diphthong іе (ыэ) through е, э, and write зьвярэ, ваўке, rather than зьвяры, ваўкі. By the way, in the pronunciation of pronouns мае, твае, свае this has already been done, so why not extend the rule to nouns as well? The author of the publication believes that it would be even better to find separate letters to reflect the diphthongs. This would help avoid misunderstandings and difficulties in learning the language (ibid., p. 105).
A. Matach’s article caught the attention of Jan Stankevich.
“Панэ, валэ, мужыке” occur not only as diphthongs but also – with a single sound э, е, depending on the locality. Grammar. A. Matach only mentions (or at least provides only examples) of masculine nouns in the nominative and accusative cases of the plural, but this same ending is also found in feminine nouns of the same cases (дочке, дзяўке) and feminine nouns in the genitive case of the singular (няма вадэ, казэ, сястрэ, дачке, etc.)” (On “панэ” and the like, in: “Kryvič”, No. 9, Kaunas, 1925, p. 103).
In the question of the territory of the spread of this feature, Y. Stankevich refers to Y. Karski, who provides examples of diphthongs from the districts of Minsk, Vitebsk, and Mogilev. However, he doubts whether there is a need to introduce this feature into the literary language.
In writing about the territorial spread of diphthongs, A. Matach also refers to Yevkhim Karski.
“As for the territorial spread of the diphthongs уо (юо), ыэ (іе), Prof. Karski in his work “Belarusians” (Book I) notes them in Hrodna province (p. 123), in the districts of Ihumen, Minsk, Slutsk, Babruysk, Barysaw of Minsk province (pp. 262, 267, 269, 295, and 336) and in the Chausy district of Mogilev province. M. Fedarovski and A. Serzhputovsky in their collections of folk tales, narratives, legends, myths, proverbs, etc., written from the words of narrators – Belarusian peasants of Vaukavysk, Slonim, Lida, Sokol, Slutsk, and Mazyr districts – quite well convey the pronunciation of these diphthongs in the indicated localities (M. Federowski, “The Belarusian People in Lithuanian Rus”, vol. I and A.K. Serzhputovsky: “Tales and Stories of Belarusians-Poleshuks”, St. Petersburg 1911)” (A. Matach, Diphthongs уо, (юо=іуо), ыэ, (іе), in: “Kryvič”, No. 9, Kaunas, 1925, p. 105).
In today’s Belarusian dialects, the spread of diphthongs is insignificant. The diphthong іе is recorded in the dialects of a small group of settlements in Brest and Gomel regions. At the same time, in Brest region, there is sometimes a coexistence of the phonemes іе and і (сіено, мніе; человік, на столі), and in Gomel region – іе and е (хліеп, ліес; сьвет, сьмелы). In some southwestern dialects, along with е open, the closed е is pronounced. This is characteristic of the dialects of the northern part of Brest region, the southern areas of Minsk and Hrodna regions, as well as some areas of Gomel region (E. Blinava, E. Myatselskaya, Belarusian Dialectology, Minsk, 1969, pp. 29-30).
The territory of the spread of the diphthong уо mainly coincides with the territory of the spread of the diphthong іе. Dialects with the diphthong уо are scattered in small islands among dialects where the etymological о is realized as closed о. Depending on the speech tempo, the diphthong уо and closed о can coexist in the same phonetic conditions, being used in the same words of one dialect. The dialects of Luninec district are indicative, where о can be realized as closed о (стол), уо (вуол, нуоч), у (вуз, вул) and even the diphthong іе (кіень, віел). The phoneme closed о appears in the dialects of Belarus, which in the north are limited by the line Lida – Karelichy – Nesvizh – Uzda – Mar’ina Horka – Babruysk – Rechitsa – Gomel; in the south – by the line Sharashova – Pruzhany – the Yaselda River – Stolin – the border with the Ukrainian SSR (ibid., pp. 30-32).