Adjarian's law

Adjarian's law is a sound law relating to the historical phonology of the Armenian language: in certain dialects, initial-syllable vowels are fronted after the consonants which reflect the inherited Proto-Indo-European (PIE) voiced aspirates. It was named after its discoverer, Hrachia Acharian, whose surname was also romanised in a Western Armenian form as Adjarian.

Compare:

• post-PIE *bʰan- "speech" > Classical Armenian բան ban > Karchevan dialect ben, Karabakh dialect pen
• post-PIE **dʰalara- "green" > Classical Armenian դալար dalar > Karabagh telar

as opposed to absence of vowel fronting after the non-aspirated voiced stops:

• PIE * dṓm-; Classical Armenian տուն tun "house" > Karchevan ton, Karabagh ton
• PIE *gʷṓws "cow" > Classical Armenian կով kov > Karabagh kov, kav, Karchevan kav

This conditioning is not a synchronic process, but rather reflects the quality of the original prevocalic consonant. In such cases the vowels first received the advanced tongue root ([+ATR]) feature in certain contexts and the [+ATR] back vowels were then fronted. The dialect of Malatya preserves the intermediate stage, with [+ATR] vowels such as /ɑ̘/.