Developmental differences in the hemodynamic response to changes in lyrics and melodies by 4- and 12-month-old infants.

Songs and speech play central roles in early caretaker-infant communicative interactions, which are crucial for infants' cognitive, social, and emotional development. Compared to speech development, however, much less is known about how infants process songs or how songs affect their development. Lyrics and melody are two key components of songs, and much of the research on song processing has examined how the two components of the songs are processed.

Processing of infant-directed speech by adults.

Adults typically address infants in a special speech mode called infant-directed speech (IDS). IDS is characterized by a special prosody (i.e.