This randomized controlled trial evaluates the effect of reciprocal maternal-infant voice exposure on maternal attachment and breastfeeding outcomes in a neonatal intensive care unit (NICU). Infants in the intervention group are exposed to recordings of their mothers' voices, while mothers simultaneously listen to recordings of their infants' sounds between the 6th and 12th postpartum hours. The intervention is administered every 2 hours for 30 minutes. Outcomes include maternal attachment, breastfeeding effectiveness, breastfeeding self-efficacy, infant feeding intention, perceived insufficient milk, and expressed breast milk volume. Neonatal physiological parameters and blood gas values are also assessed. The findings aim to support family-centered NICU care through non-invasive auditory interventions.