Perceptual Adaptation of Lexical Tones Is Degraded but Can Be Improved With Lengthened Stimulus Duration in Musically Tone-Deaf Individuals

PURPOSE: The current study investigated how individuals with congenital amusia (or "tone deafness") responded to lexical tones differed in stimulus duration and carried by distinct syllables. METHOD: Amusics were diagnosed to develop the experimental group to participate in an identification task and a discrimination task, with typical, musically intact listeners being the control group. The test stimuli were actual monosyllabic words in Mandarin Chinese, and they varied in stimulus duration (100 and 400 ms) and were presented in the low- and the high-variability conditions (the tone carried by a constant syllable and by a multitude of syllables). Participants needed to respond focusing on the tonal information in the word stimuli. RESULTS: Based on mixed-effects modeling on participants' accuracy and response time, results demonstrated that relative to the low condition, both groups were less accurate and took more time in tone processing in the high condition. Importantly, amusics showed reduced accuracy than controls in the high condition, and they obtained higher scores with longer versus shorter stimulus duration. CONCLUSIONS: Both amusics and controls could perceive syllables and tones in an integral manner. However, amusics were degraded in perceptual adaptation of tones, and they could benefit from lengthened stimulus duration for the improvement of their performance. Overall, this study deepened our understanding of amusia and provided a possible strategy for intervention programs to adopt longer auditory items to remediate amusia.