Did you say susi or shushi? measuring the emergence of robust fricative contrasts in English- and Japanese-acquiring children

While the English fricatives /s/ and /S/ can be welldifferentiated by the centroid frequency of the frication noise alone, the Japanese fricatives /s/ and /C/ cannot be. Measures of perceived spectral peak frequency and shape developed for stop bursts were adapted to describe sibilant fricative contrasts in Englishand Japanese-speaking adults and children. These measures captured both the cross-language differences and more subtle inter-individual differences related to languagespecific marking of gender. They could also be used in deriving a measure of robustness of contrast that captured cross-language differences in fricative development.