Domain specificity of lexical tone perception in early infancy: lexical tones versus musical tones

In the current study, we tested the perception of pitch variations in early infancy from a domain general perspective for two auditory domains: speech and music. 4-month-old Dutch infants were tested on their discrimination of a musical relative pitch difference, a musical absolute pitch difference, and a Mandarin lexical tone difference. Our results showed that the infants failed to discriminate between Mandarin lexical tones, whereas they succeeded in discriminating both musical pitch differences, both absolute and relative. Crucially, the musical relative pitch difference resembled that between lexical tones, while the acoustical difference between the musical pitches was even smaller than the acoustical difference between lexical tones. Yet, infants only succeeded in discriminating musical pitch contrasts. The performance of the infants who participated in all three tasks conformed to the same pattern. Our findings suggest that young infants are capable of tracking subtle pitch differences, while the lack of proficiency in processing lexical tones is likely to be speech specific and plausibly restricted to lexical tones only.