Previous work investigating listener ability to identify spoken samples of unknown foreign languages has shown that short periods of exposure provide sufficient information for reliable identification. In this study, we examined characteristics of the acoustic signature of languages in connection with identification of the target language, Korean. In experiment one, listeners were asked to distinguish spoken samples of Korean from competitor languages sharing syllable based rhythm. In the second experiment, listeners attempted to distinguish Korean from languages spoken in the same geographical area. Although the listeners had no previous knowledge of the target or of any of the competitor languages, they learned to distinguish it from the competitors. In the third experiment, listeners were asked to judge the similarity of Korean to the same set of competitor languages on a 7-point scale. Multi-dimensional scaling analyses suggest that listeners were basing their judgments on regional speaking styles as well as speaker-specific characteristics.