Recognition of vocoded speech in English by Mandarin-speaking English-learners

Abstract

The purpose of this study was to examine the impact of spectral degradation on speech processing in non-native listeners. The participants included 27 native English (L1) listeners and 43 native Mandarin listeners who learned English as a second language (L2). The speech stimuli included 12 English vowels embedded in a /hVd/ context, 20 English consonants embedded in a /Ca/ context, and HINT, CUNY, and R-SPIN sentences. All stimuli were processed using 2-, 4-, 6-, 8-, and 12-channel noise vocoders. The results showed that compared to the L1 listeners, the L2 listeners demonstrated less improvement in phoneme recognition with increasing number of channels, which was associated with the phoneme confusions due to the impact of their native language. Both consonant and vowel recognition made significant contributions to sentence recognition in the L2 listeners. In addition, the L2 listeners were less effective than the L1 listeners in applying contextual information and linguistic knowledge to sentence recognition. However, the facilitating role of contextual cues in sentence recognition was consistently present in the L2 listeners but they required more spectral information to maximize the contextual benefit in comparison to the L1 listeners. The overall perceptual performance of the L2 listeners was positively correlated with and predicted by the length of residence in the U.S.