This paper investigates language contact effects between Bulgarian dialects on the one hand, and the languages of the countries bordering Bulgaria on the other. The Bulgarian data comes from Stojkov’s Bulgarian Dialect Atlases. The paper examines three techniques to detect contact effects in pronunciation, the phone frequency method and the feature frequency method, both of which are insensitive to the order of phonological segments within words, and also Levenshtein distance, a word-based method which is order-sensitive. It also examines pronunciation effects under the hypothesis that pronunciation influences should be strongest as one approaches the border of a country which speaks the putatively influential language. The study aims to contribute to the development of more exact tools for studying language contact.