Listening to development: How electroencephalography informs infant language and music research.

In this review, we discuss how advances in infant electroencephalography (EEG) in the last quarter century have allowed developmental scientists to revisit old questions and ask new ones about early auditory perception. We specifically focus on integrating research on language and music perception given both methodological and theoretical overlaps. We discuss how EEG's high temporal resolution has provided insights into how infants process subtle changes in language and music, detecting phonemic contrasts, rhythmic patterns, and melodic cues sometimes even before these abilities are observable behaviorally. More recently, advanced methods have uncovered how neural coherence and neural tracking reflect auditory processing and predict future developmental outcomes. Coupling EEG with behavioral measures has enriched our insights into developmental milestones in cognition and perception that traditional methods may miss. Looking forward, we consider how advances in technology such as mobile EEG and hyperscanning can open doors for exploring auditory processing in naturalistic environments, such as during live caregiver interactions. We also discuss pressing challenges in the field, such as the focus on WEIRD populations and a lack of standardized data processing and analysis pipelines. Ultimately, the insights gained from infant language and music EEG research provide a strong foundation for informing parental guidance, and supporting early cognitive and linguistic growth. The continued integration of innovative technologies with rigorous, inclusive methodologies will be crucial in deepening our understanding of how infants perceive and learn language and music, two domains that connect infants to their social and cultural world.