A music perception disorder (congenital amusia) influences speech comprehension

This study investigated the underlying link between speech and music by examining whether and to what extent congenital amusia, a musical disorder characterized by degraded pitch processing, would impact spoken sentence comprehension for speakers of Mandarin, a tone language. Sixteen Mandarin-speaking amusics and 16 matched controls were tested on the intelligibility of news-like Mandarin sentences with natural and flat fundamental frequency (F0) contours (created via speech resynthesis) under four signal-to-noise (SNR) conditions (no noise, +5, 0, and -5dB SNR). While speech intelligibility in quiet and extremely noisy conditions (SNR=-5dB) was not significantly compromised by flattened F0, both amusic and control groups achieved better performance with natural-F0 sentences than flat-F0 sentences under moderately noisy conditions (SNR=+5 and 0dB). Relative to normal listeners, amusics demonstrated reduced speech intelligibility in both quiet and noise, regardless of whether the F0 contours of the sentences were natural or flattened. This deficit in speech intelligibility was not associated with impaired pitch perception in amusia. These findings provide evidence for impaired speech comprehension in congenital amusia, suggesting that the deficit of amusics extends beyond pitch processing and includes segmental processing.