Songs are better than speech for soothing babies. (Yes!) You can read more in the latest edition of the scholarly journal Infancy (or you can just read the synopsis here, Dear Parents, ye of little time and sleep):
“These findings speak to the intrinsic importance of music, and of nursery rhymes in particular, which appeal to our desire for simplicity, and repetition.”
Read all about it: Songs Better Than Speech
Chickadee Music 