Prenatal experience with low-frequency maternal-voice sounds influence neonatal perception of maternal voice samples

By sucking on a nonnutritive nipple in the presence of one discriminative stimulus, newborns were reinforced with a low-pass filtered tape recording of their mothers' voices. Sucking in the presence of a different discriminative stimulus was reinforced with unfiltered maternal-voice recordings. Filtered versions simulated maternal-voice sounds that were available before birth and unfiltered versions simulated maternal-voice sounds available after birth. Newborns in the control group could be reinforced with the same stimuli in the same way, but the voices were unfamiliar to them. Infants hearing their mothers' voices had no preference for either version, but infants hearing the unfamiliar voices preferred the unfiltered version. The difference in the between-groups responsiveness to the low-pass voice samples is consistent with the hypothesis that prenatal experience with low-frequency characteristics of maternal voices influences early postnatal perception of maternal voices.