Reduced sensitivity to emotional prosody in congenital amusia rekindles the musical protolanguage hypothesis

TLDR

Evolutionary theories posit that music and language share a common emotional protolanguage, predicting that sensitivity to emotional prosody in speech derives from music‑processing abilities. This study investigated whether individuals with congenital amusia exhibit reduced sensitivity to emotional prosody in speech. Twelve amusic participants and twelve matched controls evaluated the emotional content of 96 semantically neutral spoken phrases conveying six emotions. Amusic participants performed up to 20% worse than controls in decoding emotional prosody and reported daily difficulties, supporting the hypothesis of shared music‑language mechanisms for emotional acoustic processing.

Abstract

A number of evolutionary theories assume that music and language have a common origin as an emotional protolanguage that remains evident in overlapping functions and shared neural circuitry. The most basic prediction of this hypothesis is that sensitivity to emotion in speech prosody derives from the capacity to process music. We examined sensitivity to emotion in speech prosody in a sample of individuals with congenital amusia, a neurodevelopmental disorder characterized by deficits in processing acoustic and structural attributes of music. Twelve individuals with congenital amusia and 12 matched control participants judged the emotional expressions of 96 spoken phrases. Phrases were semantically neutral but prosodic cues (tone of voice) communicated each of six emotional states: happy, tender, afraid, irritated, sad, and no emotion. Congenitally amusic individuals were significantly worse than matched controls at decoding emotional prosody, with decoding rates for some emotions up to 20% lower than that of matched controls. They also reported difficulty understanding emotional prosody in their daily lives, suggesting some awareness of this deficit. The findings support speculations that music and language share mechanisms that trigger emotional responses to acoustic attributes, as predicted by theories that propose a common evolutionary link between these domains.