The effects of early acoustic experience on the developing brain and its relationship with infant language development

The infant brain undergoes rapid structural and functional reorganization in its first year, making it highly plastic and receptive to experience. Neural activity during this period is guided by both environmental input and internally generated activity, together shaping early cortical maps. Auditory experience, in particular, plays a critical role in forming the networks that support later language. This dissertation investigates how early acoustic experience—through exposure to temporospatially modulated, nonlinguistic stimuli—impacts the maturation of neural oscillations and auditory processing in infancy. My primary aim examines whether spontaneous EEG can serve as a reliable measure of the maturation of neural dynamics and whether it is shaped by early interactive auditory training. Infants participated in one of three conditions: Active (interactive auditory training at 4.5–6 months), Passive (passive exposure without training), or Naïve (no exposure). Spontaneous EEG was analyzed across frequency bands to test whether early experience influences the developmental trajectory of cortical activity, highlighting the importance of interactive interventions. My second aim investigates the role of timing in auditory intervention. A separate longitudinal cohort was studied, with infants in Active (trained at 6.5–8 months) and Naïve groups. This aim tests whether shifting the onset of training alters both concurrent and longer-term maturation of spontaneous oscillatory activity, providing insight into the developmental windows most sensitive to auditory input. My last aim explores how auditory processing is affected by training in the older cohort. Event-related potentials (ERPs) to rapid auditory cues are used to assess whether intervention accelerates auditory discrimination. This aim also links spontaneous and task-evoked activity by testing (a) which spontaneous frequency bands best predict task performance, and (b) which auditory biomarkers—such as ERP latency or task difficulty—most effectively characterize this relationship. Together, these aims clarify how the timing of auditory experience can influence the development of cortical networks that support language, with implications for optimizing early interventions in populations at risk for developmental language disorders (DLDs).