This is a sound change related to a vowel which has existed in the old language, but has not remained in the modern one- ѣ.
In the modern literary language it is replaced either with я or е. This occurs in the northern east speeches, while in the western dialects appears only e and in some south-east speeches- only я.
The rule in the modern literary language is: to appear я in the place of the old vowel ѣ there must be two conditions (at the same time:)
- The old vowel must be stressed
- The old vowel must be in front of hard syllable or in an ultimate one.- Syllable is hard when there is a back or mid vowel- а, ъ, о, у. It is soft when the vowel is front- е, и.
Examples: л ‘ято-л’етни зв‘яр-зверов‘е
- One pronounce and write e instead of я in words which have come from the western speeches or from Russian: човек, век, съсед, дело, употреба и др.
- One pronounce and write e instead of я when after the old vowel occurred sound ж, ч, ш : снежна, пречка, грешка.
- One pronounce and write я instead of e in the verb forms of Aorist and Imperfect in 1st ans 2nd p. plural: търпяхме, търпяхте.
Selected and translated from
Граматика за всички, Борис Кръстев, София 1995