Short-term immersion can change the location of a phonetic category boundary

Abstract

In this study the effect of immersion in a second-language (L2) speaking environment on the perception and production of English sibilants by native (L1) speakers of Danish is examined. Three groups of subjects participated. Fourteen Danish au pairs or exchange students were tested before and after a 6–12 month immersion period. Eleven Danish control subjects were tested twice without immersion. Five native English baseline subjects were tested once. Danes tend to assimilate English /s/–/sh/ to two different Danish sound categories. However, the Danish /sh/ is palatalized and has more high frequency energy than English /sh/. If the immersed subjects changed their mental specifications for /sh/ after massive input of the more low frequency English /sh/ during immersion, one might expect a perceptual category boundary shift for /s/–sh/. This shift was indeed found, using an interpolated synthetic /s/–/sh/ continuum for the identification and discrimination in both an English and a Danish language set. Production was measured using spectral moments. However, there was no clear indication of a more authentic English pronunication of /sh/ after immersion than before. The results pertain to questions regarding the reorganization of phonetic categories after L2 experience, interactions between L1 and L2 phonetic systems, and the relation between perception and production.