Perception of second language phoneme masked by first- or second-language speech in 20–60 years old listeners

Abstract

In previous research, we conducted a perceptual training on American English /r/-/l/ for Japanese adults in various age groups and found that; although the training improved identification of these phonemes in all age groups, the improvement decreased along the ages. Analyses suggested that perceptual cues of second-language (L2) phoneme perception differ across age groups. This paper investigated the decrease by focusing on perceptual cues. Listening tests were performed to assess intelligibility of Japanese words and English minimal-pairs masked by English or Japanese speech. Theoretically, in case L2 targets have phonologically non-equivalent in listener’s first-language (L1) orthography, L1-relevant cues can be used separating the targets. In case L2 targets have phonologically equivalent in listener’s L1 orthography, L2-relevant acoustic cues should be taken into perceptual cues. Masker having identical language to the perceptual cues may interfere identifying the targets. In the results of English targets which were supposed to be phonologically equivalent in Japanese orthography, young-adult Japanese showed higher effect from English masker than that of Japanese masker; conversely, older-adult Japanese showed higher effect from Japanese masker. The results suggested that young adults more focused on L2-relevant acoustic cues than elderly did. This difference may lead to the decrease in training effect.