Perceptual features of unknown foreign languages as revealed by multi-dimensional scaling

Adult listeners are able to discriminate between and often identify spoken samples of languages that are unknown to them. Two studies were designed to explore which perceptual properties inherent within the phonological structure of languages are salient to foreign language listeners. In study one, fifteen subjects were asked to judge whether pairs of spoken foreign language sentences were selected from same or different languages and to explain how they had made the judgement. A multi-dimensional scaling (MDS) was conducted on the subject responses for the 'same language' condition. The resulting map revealed that responses could be characterized along two dimensions: phonologically based psychoacoustic properties and talker specific characteristics. The two dimensions define the distinctiveness of the languages and elicited different perceptual feature relationships in subjects. In study two, this perceptual feature relationship was tested using similarity judgements. Thirty subjects rated similarity on a sevenpoint scale for the same set of sentence pairs that had been judged in study one. MDS analysis revealed that the 'different language' condition yielded a map in which the language proximities closely approximated those which had been derived by focusing on phonological properties. This finding suggests that since analysis of both 'different language' and 'same language' sentence pairs produced similar maps, perceived language similarity among foreign languages depends upon the listeners' salient organizational categories inherent within the phonological structure of language and the talker specific characteristics of voice quality and speech rate.