Child psychologists at the University of London got together with singer Imogen Heap and created what they say is the perfect song to make babies happy.

With Heap's help, the scientists created four different melodies, and then tested them on 26 kids to see which ones the kids reacted most favorably to. They did it by measuring their heart rates, and observing how much they smiled.

Of course, babies aren't made happy by music alone, so they incorporated sounds like the word "boo", the sound of a dog barking, and the sound of other babies laughing.

They also wanted the lyrics to make sense (babies don't care, but parents could get a little annoyed with total gibberish.)

The psychologists say that they wanted a female singer because babies like women's voices that sound similar to their mother's voice.

When all was said and done, they tested the song out on 20 different babies, and the kids loved it! It's called "The Happy Song," and you can check it out in the video below.