Human auditory function begins during fetal development, as early as 23 weeks’ gestation. Extrauterine language and auditory exposures during gestation affect neurobehavioral outcomes for full-term newborns. However, the typical prenatal auditory experience has not been well characterized. Such characterization is important for comparison with abnormal auditory experience during this stage of development, such as that which occurs with premature birth. We analyzed 24 000 h of auditory exposure data obtained during the final three months of prenatal/preterm brain development for typically developing fetuses and very preterm (VPT) infants. Fetuses received an estimated 2.6 ±0.6 hr/day of exposure to adult speech, nearly five times greater than the 0.53 ±0.2 hr/day for VPT infants. VPT infants instead were exposed to more noise, electronic sounds, and silence. Our findings provide the first characterization of auditory exposures for typically developing fetuses. Although it has been presumed that language exposure for NICU infants is low, typical language exposure for the equivalent stage of brain maturation has been unknown. Thus our data provide meaningful targets for interventions designed to optimize auditory exposures in NICU settings. Work supported by NIH Grant No. DC017820.
Brian B. Monson (Wed,) studied this question.