Naturally, mothers talk and sing to their babies. When I say "singing," it may not even refer to a particular tradition song. How many times have you seen a mother sings a baby to sleep without a specific tune. Mothers know how to soothe their babies best with their voices.
Lullaby is another interesting topic in both music psychology and developmental psychology. Like motherese, there are many features in lullabies across different cultures that are identical. (the form, the interval used, etc.)
Nobody would mind listening to a lullaby because it it so soothing, it reminds us the time when we were in our own cradle. The sense of comfort may be traced back to the time when we were still the womb.
Here, I would like to share two videos from websites that I recommend parents to explore.
1) Language from the Cradle is an EU sponsored project which collect lullabies across Europe. 7 of them were put onto this webiste and Youtube, here's one of them from Czech:
2) Lullabies of the world is a site that i LOVE! This is a Russian site, similar to the one i recommended above, the site shares a collection of animated films based on lullabies of different nations. As you can see from the video below, the animation is of very high quality. I downloaded all 16 of them. This one is my favorite, it's a Chukchi lullaby (they are the indigenous people who lives in the Northern part of Russia). The animation reminds me of the photo I saw recently of a mommy and baby polar bear trapped on a floating iceberg.