What's the most effective lullaby for your baby?

Hi, Well! There are many lullabies but the one that was most effective for my baby was a lullaby hum that I happen to sing by chance and it stayed. It had no words but was a simple humming. It went like; Ahhhnnn, ahhhnnnn, ahhhhnnnn, ahhhhnnnn, ahhhhhhn.....and there was this particular style that I had as how to hum it. I mean how longer each one should be hummed. ;p