The perceptual assimilation of Danish monophthongs and diphthongs by monolingual Australian English speakers

This study explores how experience with native language (L1) diphthongs influences the assimilation of non-native diphthongs. To obtain a comprehensive understanding of L1 attunement, native Australian English (AusE) speakers categorized and rated the Danish diphthongs, in addition to the monophthongs, in relation to their entire native vowel inventory. Short Danish vowels were assimilated to both lax and tense AusE vowels, and long Danish vowels were primarily categorized to tense AusE vowels. Only two of the Danish diphthongs were assimilated to an AusE diphthong, while the rest were either assimilated to an AusE tense vowel or were uncategorized. This suggests that the perceptual assimilation of non-native diphthongs is not based purely on sensitivity to vowel dynamics, but also on the perceived phonetic similarity between non-native diphthongs and L1 vowels. Implications for modelling cross-language speech perception are discussed.