If you listen to music for long enough, you’re bound to come across a tune that gets stuck in your head. Sometimes you don’t even like the song, but you find the beat incredibly hard to shake off.

This experience is known as an earworm – when a catchy piece of music is wriggling around inside your head.

Earworms are quite common and may be a universal phenomenon. Some research suggests up to 98 per cent of us have experienced an earworm – or involuntary musical imagery (INMI) as it’s known in music terms.

A study by Music researchers from the University of New South Wales (UNSW) may now have uncovered the reason why.

The UNSW research team conducted a systematic review of all the major studies on earworms to date, synthesising their findings on catchy music, tempos and pitches.

According to UNSW’s lead researcher, Professor Emery Schubert, the key ingredient is repetition.

“Drawing together the literature, it appears there’s an essential characteristic necessary for a song to roll out the earworms – the music itself must have some repetition in it,” Professor Schubert said.

Most reported earworms are the chorus of songs, which are inevitably the pieces of the music repeated the most.

“Research on earworms to date analyses what’s in the hook – the short riff or passage to catch the ear of the listener,” Professor Schubert said.

“But what hasn’t been considered is that the hook is invariably repeated in the music, most commonly in the chorus.

“The implication is that earworms might not have anything to do with the musical features at all. It largely doesn’t matter what the music is, as long as repetition is part of the music structure.”

But the repetition in a song is only one part of the equation. There are several preconditions for an earworm to occur, including recency and familiarity with the music. To activate an earworm, we must also be in what’s called a low-attentional state, according to the study.

“It’s sometimes referred to as mind wandering, which is a state of relaxation. In other words, if you’re deeply engaged with the environment you are in, really concentrating on a task, then you won’t get an earworm,” Professor Schubert said.

“Inside your relaxed mind, you don’t have to follow the exact structure of the music. Your mind is free to wander wherever it likes, and the easiest place to go is the repeated fragment and to simply repeat it.”

While earworms can be an unwelcome distraction at times, many people find them enjoyable.

“It’s a bit of a misconception that they’re a problem,” Prof. Schubert said. “We’re starting to see more research suggesting many find getting an earworm to be quite pleasant and it is not an issue that needs solving.”

Professor Schubert explained that the cases where earworms are dreaded is usually when the music itself is not liked.

“The earworm doesn’t care about enjoyment; it cares about how familiar the music is, how recently something similar was heard, and whether the music contains repetition.”

Although an earworm is not a medical condition, or considered a danger in most cases, for those hoping to expel an unwelcome tune, there are many theories for how to get rid of them.

“You may be able to wrap up an earworm by either finishing off the music, consciously thinking of another piece of music, or by removing yourself from the triggers, such as words or memories that relate to the music or lyrics,” Professor Schubert said.

“We don’t go out to find earworms, but earworms find us… There are still several puzzles we need to solve to understand not only their nature but what it might mean for cognition and memory.”

Feature Image: Kashirin Nickolai. Wiki Creative Commons Attribution 2.0.