Sources of illusion in consonant cluster perception

Previous studies have shown that listeners have difficulty discriminating between non-native CC sequences and licit alternatives (e.g. Japanese [ebzo]-[ebuzo], English [bnif]-[beschwanif]) (Berent et al., 2007; Dupoux et al., 1999). Some have argued that the difficulty in distinguishing these illicit-licit pairs is due to a "perceptual illusion" caused by the phonological system, which prevents listeners from accurately perceiving a phonotactically unattested consonant cluster. In this study, we explore this and other sources of perceptual illusion by presenting English listeners with non-native word-initial clusters paired with various modifications, including epenthesis, deletion, C 1 change, and prothesis, in both AX and ABX discrimination tasks (e.g. [zmatu]-[zeschwamatu], [matu], [smatu], or [eschwazmatu]). For English listeners, fricative-initial sequences are most often confused with prothesis, stop-nasal sequences with deletion or change of the first consonant, and stop-stop sequences with vowel insertion. The pattern of results across tasks indicates that in addition to interference from the phonological system, sources of perceptual illusion include language-specific phonetic knowledge, the acoustic similarity of the stimulus items, the task itself, and the number of modifications to illicit sequences used in the experiment.