Grazer Linguistische Studien 92 (Herbst 2020); S. 21-43 DOI: 10.25364/04.47:2020.92.2 The Differential Impact of Linguistic Experience on the Discrimination and Categorization of Non-Native Sounds in Foreign Language Learners Fatemeh Nemati, Mona Ahmadian & Abbas Abbasi Persian Gulf University, Bushehr, Iran Abstract. Speech perception has been extensively proven to be modulated by exposure to native language. As the perception of non- native sounds is predicted to be influenced by the phonological experiences of learners, it is worthwhile to study the perception of non-native speech sounds by learners who share the same language learning ecology but possess different linguistic repertoires. This study focuses on the perception of English dental fricatives, [θ] and [ð], by Persian and Arabic-Persian EFL learners, with the former lacking these sounds in their L1 and the latter having them in their L1 (Arabic) phonological system. To examine the perception of these sounds by both groups and their perceptual substitutes, 90 Iranian EFL learners – 32 Arabic-Persian bilinguals and 58 Persian monolinguals – completed a discrimination and an identification task. Although the results indicated a significant difference only in the identification of [θ], the trend showed that Arabic-Persian learners were more successful in the two tasks, presumably due to activating perceptual routines from their L1. The dominant substitution made in the two tasks by both groups reveals the prominence of acoustic features rather than articulatory similarity in the perception of the dental fricatives. Keywords. English, Persian, Arabic, dental fricatives, non-native speech perception, discrimination, identification, perceptual substitution, monolinguals, bilinguals