Recognition of foreign-accented vocoded speech by native English listeners

This study examined how talker accentedness affects the recognition of noise-vocoded speech by native English listeners and how contextual information interplays with talker accentedness during this process. The listeners included 20 native English-speaking, normal-hearing adults aged between 19 and 23 years old. The stimuli were English Hearing in Noise Test (HINT) and Revised Speech Perception in Noise (R-SPIN) sentences produced by four native Mandarin talkers (two males and two females) who learned English as a second language. Two talkers (one in each sex) had a mild foreign accent and the other two had a moderate foreign accent. A six-channel noise vocoder was used to process the stimulus sentences. The vocoder-processed and unprocessed sentences were presented to the listeners. The results revealed that talkers' foreign accents introduced additional detrimental effects besides spectral degradation and that the negative effect was exacerbated as the foreign accent became stronger. While the contextual information provided a beneficial role in recognizing mildly accented vocoded speech, the magnitude of contextual benefit decreased as the talkers' accentedness increased. These findings revealed the joint influence of talker variability and sentence context on the perception of degraded speech.