Infant wearing a fNIRS cap allowing to measure changes in the brain hemodynamic response.

Acquiring language is a complex journey requiring various neural and cognitive skills from early childhood. One significant challenge children face is deciphering grammatical connections between words, even when separated in speech. For example, in the sentence "She, who never drinks coffee, sleeps more," identifying "she" as the subject of "sleeps" mirrors the simpler "She sleeps well," despite added words. Prosody, known as "the melody of speech," plays a crucial role in communication and language comprehension. This study indicates that when prosody accompanies speech, infants are better able to recognize distant grammatical patterns, as evidenced by changes in brain activity and behavior. Previously, it was thought infants couldn't grasp such patterns until their first year, but the study reveals sensitivity in nine-month-olds. The work assessed infants' sensitivity to these patterns—with and without prosody—by adding high pitch to relevant syllables and measuring behaviour and using near-infrared spectroscopy (NIRS) to monitor neural responses. When exposed to flat speech lacking prosodic cues, infants didn't exhibit learning-related behaviors, whereas pitch signals enhanced both neural responses and learning. This highlights infants' remarkable language learning abilities, evident even before their first birthday. However, robust learning at this age relies on statistical and prosodic regularities in speech, aiding in detecting grammatical structures. The findings underscore the significance of prosody—rhythm, stress, pitch, pauses—in facilitating language acquisition, serving as a scaffold for infants' linguistic development.