Influence of gestational age and postnatal age on speech sound processing in NICU infants

Abstract

The study examined the effect of gestational (GA) and postnatal (PNA) age on speech sound perception in infants. Auditory ERPs were recorded in response to speech sounds (CV syllables) in 50 infant NICU patients (born at 24–40 weeks gestation) prior to discharge. Efficiency of speech perception was quantified as absolute difference in mean amplitudes of ERPs in response to vowel (/a/–/u/) and consonant (/b/–/g/, /d/–/g/) contrasts within 150–250, 250–400, 400–700 ms after stimulus onset. Results indicated that both GA and PNA affected speech sound processing. These effects were more pronounced for consonant than vowel contrasts. Increasing PNA was associated with greater sound discrimination in infants born at or after 30 weeks GA, while minimal PNA-related changes were observed for infants with GA less than 30 weeks. Our findings suggest that a certain level of brain maturity at birth is necessary to benefit from postnatal experience in the first 4 months of life, and both gestational and postnatal ages need to be considered when evaluating infant brain responses.

Critical Periods in Speech Perception: New Directions

“…However, in an event-related potential (ERP) study of discrimination of the Hindi /da/-/Da/ distinction, Peña and colleagues (2012) reported that infants born premature continued discriminating the Hindi (nonnative) consonants until they reached a chronological age that was approximately 12 weeks older than that of the full-term infants; that is, when they had reached the same gestational age (time from conception) as had the full-term infants. Similarly, a recent ERP study indicates that when listening to consonant-vowel syllables, the spontaneous neural response to speech in premature infants does not show obvious effects of listening experience in the first several months after birth (Key et al 2012). Thus, it appears that prior to a critical point in maturation-even when environmental input is provided-the developing human brain does not begin to settle on the native speech sound categories.…”

Hemisphere Differences in Speech-Sound Event-Related Potentials in Intensive Care Neonates

“…14 Additionally, prior studies in infants showed that this window demonstrated the best variation between term and preterm infant’s response to sound. 21 …”

The Effect of Prenatal Auditory Enrichment on Perceptual Narrowing in Bobwhite Quail Neonates

“…However, infants born at or before 30 weeks of gestation could not reliably make those same distinctions compared to counterparts with the same postnatal age. Key et al (2012) suggest that a minimum level of brain maturity at birth is required for postnatal experience to impact perceptual narrowing and, in turn, milestones of language acquisition.…”

“…Key, Lambert, Aschner, and Maitre (2012) examined the effects of both gestational age and postnatal age of human infants in the NICU. When comparing infants born between 24-40 weeks gestation on auditory ERPs for native phoneme contrasts, Key et al (2012) found a threshold for prenatal development.…”

“…Key, Lambert, Aschner, and Maitre (2012) examined the effects of both gestational age and postnatal age of human infants in the NICU. When comparing infants born between 24-40 weeks gestation on auditory ERPs for native phoneme contrasts, Key et al (2012) found a threshold for prenatal development. Overall, as the infant accrues experience postnatally, it becomes more adept at making native phoneme contrasts, older infants displaying neurological responses in line with correct discrimination of those speech sounds.…”