Effect of frequency shifts on talker recognition in native and foreign-accented speech

Abstract

The present study examined the effect of frequency shifts on perceived talker recognition in foreign-accented speech compared to native-accented speech. Sentences were processed using the STRAIGHT vocoder. The spectral envelope and the fundamental frequency were shifted up or down in seven steps (3 up, 3 down plus unshifted) using scale factors of 8% and 30%, respectively, at each step. Listeners heard pairs of sentences and were asked to judge whether the identity of the talker was the same or different. Frequency shifts had similar effects for native- and foreign-accent conditions, in that listeners perceived the shifted versions as different talkers when, in fact, the talkers were the same. However, listeners were more likely to judge native-accented sentence pairs as the same talker regardless of whether or not they were the same; foreign-accented sentence pairs were more likely to be heard as different talkers. Overall, these results indicate that patterns of frequency-shifted foreign-accented speech are similar to previously reported patterns for frequency-shifted native speech; however, the small differences in patterns between the accent conditions might be attributed to listeners being less familiar with non-native speech patterns.