Rhythmic discrimination of languages in infants with hearing loss

At birth, newborns show sensitivity to the rhythm of their native language, i.e. the language they heard prenatally, being able to discriminate it from a rhythmically different language (Pena et al. 2003, May et al., 2018). A current hypothesis (Gervain, 2018) suggests that prosody provides the basis of early speech perception and helps infants discover other linguistic units after birth, when the full-spectrum speech signal is available. Prenatal experience is thus hypothesized to be foundational for language learning. But what happens when prenatal experience is disrupted?

To investigate this, we are testing the ability of 0-10 month-old infants with hearing loss (HL) to discriminate their native language (Italian) from a rhythmically different unfamiliar language (English). Sentences in both languages are presented forward and backward. Backward speech, with perturbed temporal features, is a standardly used non-linguistic control (Pena et al. 2003). A control group of age-matched normal-hearing (NH) infants is also tested. Infants’ brain responses are recorded using functional Near-Infrared Spectroscopy (fNIRS) covering the frontal, temporal, and parietal regions, bilaterally.

Data collection is ongoing. Preliminary results (n=17 HL, n=18 NH) suggest that NH babies show overall larger responses than HL babies. In addition, it seems that Italian is triggering larger brain responses than English in the two groups.

If found, a deficit in prosodic perception in infants with hearing loss could provide theoretical insights into the role of prenatal and early postnatal experience in language development, as well as important applications for screening and intervention in this population.