Identification of English voiceless fricatives by Japanese listeners: The influence of vowel context on sensitivity and response bias

Abstract

In order to examine the ability of native Japanese speakers to distinguish between English voiceless fricatives, a five-alternative, forced-choice (5AFC) test was administered to 104 Japanese students of English. The stimuli consisted of 75 nonsense syllables in which five fricatives (/f/, /s/, /∫/, /θ/, /h/) were presented in five vowel environments (/i ε a o u/) and in three different consonant contexts, and were spoken by three native speakers of English. The identification rates were submitted to signal-detection-theoretic (SDT) analysis (measured by d'), multidimensional-scaling (MDS) analysis, and cluster analysis. Overall, identification rates ranged from a maximum of 88% for the /∫/ stimuli to 55% for the /θ/ stimuli. The results showed that both vowel environment and consonant context had an effect on the listeners' perception of the stimuli in this study. A control group of six native English subjects took the same identification test using the same procedure. All of the control listeners had no difficulty in identifying the target fricatives except in the case of the /f/-/θ/contrast.