Tone Merging Patterns in Congenital Amusia in Hong Kong Cantonese

Congenital amusia is a neurodevelopmental disorder, affecting fine-grained musical pitch processing without brain injury. This disorder also affects pitch processing in speech such as lexical tone perception. On the other hand, the phenomenon of tone merging has been observed among some speakers of Hong Kong Cantonese (HKC), who exhibit confusion between certain tone pairs in perception and/or production. It has been reported that tone merging may relate to individual variation in cognitive abilities of working memory and attention. The current study is a first attempt to investigate the relationship between amusia and tone merging by examining tone merging patterns in perception of amusics in HKC and their cognitive abilities of working memory and attention as well as pitch threshold. The results revealed a different profile of amusics from that of merger groups reported in previous studies. Amusics exhibited a profound impairment in discriminating tones compared to musically intact controls, which appeared to differ from the highly selective perceptual confusion of tone pairs reported in the merger groups. Regarding cognitive measures, amusics also demonstrated broad deficits in selective attention, working memory and inhibitory control. The temporary results imply that amusia might have a limited contribution to the previously reported tone merging.