Recorded Contingent Caregiver Voice Independently Improves Neural Speech Processing in Hospitalized Preterm Infants:...

Background/Objectives: The atypical NICU auditory environment can disrupt neural plasticity critical for language development in preterm infants. Recorded caregiver's voice offers input when bedside presence is infeasible, and evidence suggests contingency, delivering the recording in response to infant behavior, is key to its benefit. This study tested whether caregiver's recorded voice contingent on non-nutritive sucking (NNS) enhances neural speech processing beyond passive exposure. Methods: This randomized controlled trial enrolled preterm infants born before 35 weeks gestational age (GA), and between 32 0/7-35 6/7 weeks corrected GA at start. Infants were randomized to an intervention group receiving caregiver's voice contingent on NNS, or a control group receiving passive voice exposure. Primary outcomes were post-intervention auditory ERP responses at left (T5) and right (T6) temporal locations, adjusted for pre-intervention EEG. Sensitivity analyses controlled for GA and maternal education; secondary analyses examined bed type, room type, and sound levels. Results: Of 214 infants enrolled, 97 intervention and 94 control infants completed the protocol (median GA 31.9 weeks, median corrected GA at start 33.9 weeks). The intervention group showed significantly greater speech-sound processing at T5 (β = 0.023, 95% CI [0.002, 0.044], p = 0.036, d = 0.31), with a borderline effect at T6 (β = 0.022, 95% CI [0.000, 0.045], p = 0.054, d = 0.28), both strengthened in sensitivity analyses. No significant interactions emerged with bed type, room type, or sound level. Conclusions: Contingent, infant-activated caregiver-voice exposure improves auditory ERP responses in preterm infants, independent of environmental factors, suggesting active engagement, not voice alone, as the driver of change. Further studies are warranted.