The Impact of First Language Interference on English Pronunciation Accuracy Among Acehnese EFL Learners

Accurate pronunciation plays a vital role in oral communication and mutual intelligibility; however, English as a Foreign Language (EFL) learners frequently encounter severe pronunciation barriers due to first language (L1) negative transfer. English possesses nine fricative phonemes (/f, v, θ, ð, s, z, ʃ, ʒ, h/), which are produced by forcing air through a narrow passage in the vocal tract to create continuous friction. This study investigates the impact of Acehnese L1 phonological interference on the pronunciation accuracy of English dental fricatives (/θ/ and /ð/) among Acehnese EFL learners. Utilizing a descriptive qualitative research approach, data were collected from eight native Acehnese speakers residing in Gampong Iboih, Sabang, who regularly engage in tourism-driven oral English interaction. Participants completed oral reading tasks consisting of a 24-word isolated list and 10 contextual sentences containing target phonemes in initial, medial, and final positions. The acoustic recordings were transcribed using narrow phonetic notation according to the International Phonetic Alphabet (IPA) to measure accuracy quantitatively. The results show a widespread pattern of phonological substitution caused by structural gaps in L1. While the voiced dental fricative /ð/ was nearly always replaced by the voiced alveolar stop [d], the voiceless dental fricative /θ/, which necessitates placing the tongue tip slightly between the upper and lower teeth and expelling airflow, was systematically replaced with the voiceless alveolar stop [t] or aspirated stop [th]. Quantitatively, the total pronunciation accuracy decreased further in connected sentence tasks (3.8%) and remained notably low across the word list (7.3%), indicating that increased cognitive load increases reliance on native articulatory habits. The primary causes of these systematic errors stem from the complete absence of interdental fricatives in the Acehnese phonetic inventory, a lack of interdental muscle memory, and the cognitive mismapping of English fricatives onto native plosive categories.