This is why songs get stuck in your head - even when you don't like them

Read the full transcript of this episode. 

For some people, it's Baby Shark. For others it's Billie Eilish's bad guy. For 12-year-old Tai Poole, host of the CBC Podcast Tai Asks Why, the song that is constantly playing in a loop in his head is Luis Fonsi's Despacito. 

He doesn't even really like the song, or remember playing it recently, but it's been in his head for months, so Tai set out to learn why that is—and how to get rid of it for good.

Earworms, also known in the scientific community as involuntary musical imagery, are a nearly universal experience, and it happens in cultures around the world. One study shows that 92 percent of people report having songs stuck in their heads at least once a week.

"Earworms are musical thoughts. So at their core they are thoughts like any other thoughts, but you also have the extra level of association and triggers that might elicit the music in your head." says Dr. Ioanna Filippidi, a music psychologist at the Royal Northern College of Music in Manchester, UK. 

And it turns out, even music psychologists get songs stuck in their heads - her current earworm is Kate Bush's Wuthering Heights.

Dr. Filippidi's research shows that earworms happen when your brain makes a connection with a song and something else in your environment, whether you consciously notice the association or not. 

"If you're doing the dishes and you always listen to music when you're doing the dishes, then you might have music in your head when you were doing the dishes, just because your mind has associated the two activities," she told Tai during a recent episode of Tai Asks Why. 

But these musical connections can come from multiple directions, even at the same time, which is why it can seem to strike at random. 

"The problem is that the mind makes associations all the time so you might be always listening to music when you're doing the dishes but you might always listen to music when you're sad. So if you're doing the dishes and you're sad then we don't know which one will overlap the other."

Simple and repetitive: the perfect earworm

And songwriters know how to make sure it's their songs that get embedded in your brains.

"Catchiness is partly simplicity, it's partly in what we call motifs or a certain sequence of notes.
And then it's also repetition.  If you have very complex melodies or complex rhythms people can't remember them," says Mike McCurlie of MJM Media, the production company behind award-winning jingles such as those for African Lion Safari, Pizza Pizza, and Mandarin.

"As human beings we love to recognize patterns. So if we hear, like, Beethoven's Fifth [Symphony], you kind of recognize three notes and then it drops and then three notes and it drops and throughout that whole symphony," he said.

"It's the same in pop songs. It's all very dependent on the hook that the composer comes up with. And it might be a lyrical hook. It might be an instrumental hook. It's a little pattern that keeps repeating throughout the song."

Earworms aren't necessarily a bad thing. McCurlie mentions how using the same melody in nursery rhymes like Baa Baa Black Sheep and Twinkle Twinkle Little Star helps many children learn the alphabet.

"How could we ever have remembered the alphabet if it wasn't for the song? Like you take 26 random letters put them in an order like that. You heard your mom singing those nursery rhymes before you had to learn the alphabet so it's a kind of pre-training so you'd know the melody."

The million dollar question - how to get rid of earworms 

The best way to get rid of an earworm, Dr. Filippidi tells Tai, changes depending on the individual, much like the earworm itself. 

"So there is only one proven method. But, disclaimer, it has never worked for me no matter how hard I tried. But, the researchers said that if you chew gum vigorously and try not to think of the music in your head then that would lead to less involuntary musical thoughts," she said.

"Other people have different strategies and if one works for you then stick to it. So listen to it is one strategy, looking up the lyrics is another listening or humming something completely different is another but to me, that only gives me the new earworm."

CBC Podcasts asked podcast producers and listeners what their latest earworms are. The result is this Spotfify playlist.