Effect of Noise on Lexical Tone Perception in Cantonese-Speaking Amusics

Congenital amusia is a neurogenetic disorder affecting musical pitch processing. It also affects lexical tone perception. It is well documented that noisy conditions impact speech perception in second language learners and cochlear implant users. However, it is yet unclear whether and how noise affects lexical tone perception in the amusics. This paper examined the effect of multi-talker babble noise [1] on lexical tone identification and discrimination in 14 Cantonese-speaking amusics and 14 controls at three levels of signal-to-noise ratio (SNR). Results reveal that the amusics were less accurate in the identification of tones compared to controls in all SNR conditions. They also showed degraded performance in the discrimination, but less severe than in the identification. These results confirmed that amusia influences lexical tone processing. But the amusics were not influenced more by noise than the controls in either identification or discrimination. This indicates that the deficits of amusia may not be due to the lack of native-like language processing mechanisms or are mechanical in nature, as in the case of second language learners and cochlear implant users. Instead, the amusics may be impaired in the linguistic processing of native tones, showing impaired tone perception already under the clear condition.