Learning to play music changes brain structure and function, and there is much interest in the idea that these changes might transfer to skills beyond music. Many studies examined if music training improves abilities such as speech and intelligence. However, remarkably little is known about potential transfer effects to social skills, notably the ability to process emotional voices and faces. This effect could be hypothesized from the fundamental link between music and social and emotion processes, and is of central theoretical and applied importance: for understanding brain plasticity, the neurocognitive links between music and socio-emotional abilities, and the potential of music as a therapeutic tool. This project asks if music training improves socio-emotional processing, focusing on three unresolved questions. First, we determine if adult musicians reliably outperform non-musicians at recognizing emotions, and establish the scope of the effect: is it limited to voices, or does it extend to the visual domain (faces)? Is it limited to formally trained individuals,or does it extend to musically sophisticated non-musicians, who developed music skills via informal engagement withmusic? This will clarify previous mixed findings and provide a mechanistic understanding of the effect. A new tool for measuring musical sophistication will be validated and made available to the community. Second, we will combine state-of-the-art magnetic resonance imaging and electrophysiological techniques to delineate the neural mechanisms of the effect. This includes examining how emotions are represented in the trained brain, modulations in the processing time course, and changes in functional connectivity and brain anatomy. This comprehensive approach will add critical new insights into how music drives plasticity. Third, we will conduct a longitudinal study in children to test the effects of a music training program on socio-emotional processing, including pre- and post- training ass...