THAT'S THE WHY:One of my favourite words is earworm. A translation from the German Ohrwurm, it refers to a song or musical phrase that has lodged squarely in your head and is playing on loop.

So why is it that some tunes are so catchy that minutes or hours after you heard them in passing, they can still be stuck in your brain?

The process is like having to scratch a “cognitive itch” by rehearsing the tune mentally over and over, according to marketing professor James J Kellaris in a 2001 news piece published by the University of Cincinnati.

He reckons that almost everyone experiences earworms at some point, and he identifies some of the characteristics that tend to crop up in ditties that tread the groove over and over: repetition, musical simplicity and an incongruous or unexpected twist.

Meanwhile, a new study in the British Journal of Psychology has found that most people are not bothered by earworms, but “those who consider music to be important to them report earworms as longer, and harder to control, than those who consider music as less important.”

That paper goes on to suggest that passively accepting the stuck song may be more effective than actively trying to block or eliminate it.

So Kylie knew exactly what she was doing when she sang, I Can’t Get You out of My Head. See if you catch yourself playing that one on your neural iPod later on today.

And if you want to share your earworm experiences with researchers at Goldsmiths, University of London, and BBC6, go to earwormery.wordpress.com.