INTERFERENSI BAHASA DAERAH DALAM KOMUNIKASI FORMAL DI SMK MUHAMMADIYAH 6 ROGOJAMPI

Interference affects understanding and mastery of Indonesian, the official language of the country, and instruction in many educational institutions. It also provides insight into the challenges regional language students face in using Indonesian appropriately. This research aims to describe the form, causal factors and influence of interference from the use of regional languages in formal communication at SMK Muhammadiyah 6 Rogojampi. This research uses qualitative methods through recording techniques carried out using video during the communication process, and recording the results of teacher and student conversations from videos of formal communication processes at school. The data obtained is classified and analyzed according to the existing problem formulation. The results showed that there was interference including phonology, morphology and syntax. Interference factors occur due to the influence of students' mastery of two languages, low loyalty of recipient language users, and habits brought from the mother tongue. This influence shows that the use of regional languages, especially in the form of influence on sentence structure and vocabulary, often appears in everyday communication, even in formal contexts. This shows that there is a tendency for students to mix regional languages with Indonesian in oral conversations which can affect the effectiveness of formal communication in the school environment.