Two scientists and an award-winning composer have found what just might be the perfect song to keep a baby happy.

Picture this: you’re with a baby, watching happily as it laughs at the world when suddenly you see the telltale signs of a tantrum about to begin.

How good would it be if you could instantly turn that frown into a smile?

That might just be possible thanks to the academics who analysed what makes babies smile and set out to create a song scientifically proven to make infants happy.

Caspar Addyman, a lecturer in developmental psychology at the University of London, was already an expert on baby laughter when he and music psychologist Lauren Stewart were asked if it was possible to create a song that ticks every box to make a baby happy.

“The first step was to discover what was already known about the sounds and music that might make babies happy,” Mr Addyman said when announcing the results of his work this week.

“The song ought to be in a major key with a simple and repetitive main melody with musical devices like drum rolls, key changes and rising pitch glides to provide opportunities for anticipation and surprise.”

Because babies’ heart rates are higher than adults, the song should be faster too, with 163 beats per minute ideal.

“And finally, it should have an energetic female vocal, ideally recorded in the presence of an actual baby,” Mr Addyman said.

And then there are the lyrics.

Polling 2500 parents to find out what words and noises made their children happy, they came up with a list including “Boo!”, raspberries, sneezing, animal sounds and (of course) other babies laughing.

All that data went to Grammy Award winner Imogen Heap and the result is The Happy Song, two minutes and 42 seconds that just might be the answer to parents’ prayers.

https://www.youtube.com/watch?v=XjpraGVs2Sg

“If you ever met an excited toddler or young baby, you will know that two and a half minutes is a long time to hold the attention of even one child, let alone two dozen,” Mr Addyman said of the moment they debuted their creation on a room full of babies.

“When The Happy Song played we were met by a sea of entranced little faces. This final bit wasn’t the most scientific as tests go but it definitely convinced me we had a hit on our hands.”

Testing for ourselves, we asked Australian parents to play it for their kids.

One parent said her toddler immediately stopped and bounced happily through repeated plays.

Two older kids in the room abandoned their computers to watch, then spent the next hour humming the tune.

“They put down Minecraft!” the mother said. “What witchcraft is this!”

But be warned: this might make your baby smile, but one of Ms Stewart’s areas of expertise is “earworms”, songs that get stuck in your head – and this one is no exception.

So try it on your baby next time they need a smile. But don’t blame us if you’re singing The Happy Song for the rest of the day.