Learning Two Tone Languages Enhances The Brainstem Encoding Of Lexical Tones

Auditory brainstem encoding is influenced by experience dependent factors such as language and music. Tone language speakers exhibit more robust brainstem encoding of lexical tones than non-tone language speakers. Studies suggest that the effects of experience with a tone language generalize to the brainstem encoding of lexical tones from other tone languages. However, the effects of learning two tone languages, with different tonal systems, on brainstem encoding of lexical pitch are unknown. In the current study, we investigated whether or not the experience with two tone languages (Mandarin and Cantonese) enhances the brainstem encoding of lexical pitch, using frequency following response (FFR). Mandarin has four lexical tones- high level, rising, dipping, and falling while Cantonese has a richer tone system with three level tones (high, mid, low), two rising tones (high and low), and one falling tone. We compared speakers fluent in Cantonese vs. those fluent in both Cantonese and Mandarin on their brainstem encoding of Cantonese and Mandarin lexical tones. We found that the Cantonese-Mandarin speakers exhibited more robust brainstem encoding of the lexical tones as compared to Cantonese speakers. From the current findings, we conclude that learning two tone languages may enhance lexical pitch encoding at the brainstem.