Perceptual assimilation and free classification of German vowels by American English listeners

In order to investigate listeners’ perceptual patterns regarding segments from an unfamiliar language, researchers commonly employ perceptual assimilation tasks. These tasks investigate the perceptual similarity of non-native sounds to L1 sounds, but do not provide information on the perceived similarity among non-native sounds. In order to examine how German vowels are perceived by naïve American English listeners, both in their similarity to L1 vowels and to each other, this study employs a perceptual assimilation task and a free classification task, a tool previously used for investigating perceived (dis-)similarities of stimuli. The perceptual assimilation results largely replicate previous findings on American English assimilation of German vowels; however, the free classification results suggest that assimilation patterns are not reliable indicators of the German vowels’ perceptual similarity to each other. These results indicate that free classification offers an efficient means of gathering corroborating data that can be used to enhance cross-linguistic perception research.