Project Summary Music training has long been used as a treatment to enhance neural function and behavioral outcomes in clinical populations. There is an extensive literature describing how music-training and tonal language learning alters the brain and behavior in healthy adult populations. One important unresolved issue is how music experience and language experience interact in the developing brain. Understanding how and to what extent music and language experience modulate cortical dynamics for brain functions (e.g., music and speech processing) will open a crucial door to treat a myriad of neurological conditions with an auditory or language base. The long-term overarching goal of this project is to uncover the causal relationship between brain networks and behavioral aspects of music sensitivity in the developing brain. This first project proposes to apply a combination of a music neurophysiological paradigm, a lexical tone neurophysiological paradigm and behavioral measures to uncover the complex interaction between music and lexical tone processing in the developing brain. The three specific aims are: 1) To determine the cortical maturational trajectories of auditory processing in terms of six main music features (rhythm, intensity, location, slide, pitch, and timbre) in 5-10 year old children. Event-related potential (ERP) responses will be compared across age groups. A multi-feature music oddball paradigm that includes six types of feature changes will be used. Significance: This aim is essential for examining brain developmental plasticity for the processing of different music features. 2) To determine whether early music training, tonal language, bilingual language experience and different English dialects modulate cortical sensitivity to the above-mentioned six main music features. The ERP responses will be compared across monolingual-bilingual, tonal-nontonal language, mainstream American English dialect – African American English dialect groups (monolingual English with mainstream American English dialect with and without music training, monolingual English with African American English dialect, bilingual Spanish- English and bilingual Mandarin-English). Significance: These comparisons are important because it will, for the first time, reveal the intricate relationship between dialectal experience, lexical tone development, bilingual development and brain development for music processing at the cortical level. 3) To determine whether, and to what extent, early music experience and language experience modulate cortical sensitivity to lexical tone processing. The ERP responses to lexical tone contrast will be compared across the above-mentioned groups of children. Significance: These comparisons are important because it will shed light on the relationship between early music training and the neural representations for speech processing.