Frequency modulation detection in Mandarin Chinese-speaking amusics across modulation rate, carrier frequency, and stimulus duration.

Frequency modulation (FM) detection was examined in Mandarin Chinese-speaking listeners with congenital amusia, including pure amusics and tone agnosics (without and with lexical tone deficits, respectively). Thresholds were measured across modulation rates, carrier frequencies, and stimulus durations. Amusics exhibited elevated FM detection thresholds relative to controls, with no difference between pure amusics and tone agnosics. No significant interactions were observed between listener group and acoustic parameters, suggesting the group difference did not vary reliably across modulation rates, carrier frequencies, or stimulus durations. These findings indicate an impairment in dynamic pitch encoding in congenital amusia, independent of lexical tone deficits.