Earworms: Why Songs Get Stuck in Your Head

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As I took my morning walk today, I realised I was humming the same verse of a pop song I must have heard on the radio yesterday. For the life of me I couldn’t remember the name of the song or most of the lyrics, but that one part kept replaying in my head on an endless loop. No matter how much I tried to distract myself by listening to the birds chirping overhead or watching squirrels gather acorns on the path before me, the tune persisted. That’s when it hit me – I had an earworm.

You’re probably familiar with the phenomenon even if you didn’t know it had a name. Earworms refer to catchy songs or melodies that replay involuntarily inside your head long after you’ve stopped listening to the music. You might suddenly find yourself humming a tune, singing the chorus of a pop song, or even imagining an instrumental solo or musical riff that gets stuck on mental repeat. The experience can be annoying when it happens at inopportune moments, yet also demonstrates the brain’s incredible ability to retain music and lyrics after just one or two exposures.

So what causes these stubborn melodies to take residence inside our minds? And more curiously, why is it so hard to get them out once they’re in there? Understanding the science behind earworms provides some fascinating clues into how the brain perceives, processes, and remembers music on a neurological level.

From Sound Waves to Brain Waves: How We Encode Music
The journey of a song from your stereo to your subconscious starts with the ears. Sound waves are funnelled down the ear canal until they reach the eardrum, causing it to vibrate. These vibrations pass through a series of tiny bones in the middle ear, amplifying them to the perfect intensity for the inner ear, or cochlea, to translate into neural signals.

The cochlea is shaped like a snail shell and filled with specialised sensory tissue lined with thousands of microscopic hair cells. Sound vibrations ripple through this tissue, triggering hair cells that in turn excite the auditory nerve fibres. The auditory nerve carries these signals to the brain, where a dedicated region of the cortex interprets the neural patterns as musical elements like rhythm, melody, pitch, tempo, and timbre.

In fact, neuroimaging studies show distinctive neural pathways light up all over the brain in response to music, spanning an interconnected web of auditory, motor, linguistic, memory, and even emotional centres. Regions like the cerebellum and basal ganglia, for instance, track beat and tempo, while language areas decode lyrics. Areas involved in movement may also activate in response to danceable rhythms. Pleasant songs trigger reward centres like the nucleus accumbens, releasing feel-good neurotransmitters that emotionally colour our musical experiences.

This broad neural connectivity allows the brain to richly represent music with all its nuances – and provides ample opportunity for songs to get lodged inside our heads.

The Sticky Song Effect: Why Music Is So Memorable
From an evolutionary standpoint, having catchy, memorable tunes ingrained in our minds would have offered a survival advantage. Music provides a pleasurable reward that motivates us to seek it out and share it with others. In fact, scientists theorise humans may have developed musicality as a way to strengthen social bonds.

Of course, it’s not always socially convenient when the latest pop song hijacks your mental soundtrack as an earworm. Yet their stubborn stickiness clearly demonstrates how effectively the brain encodes music into memory. Auditory cues seem to garner added traction in our mental landscape compared to other sensory stimuli. Even short musical phrases easily bore into our subconscious relative to verbal information.

Much like how catchy advertising jingles brand themselves into consumers’ minds, the brain latches onto musical hooks that become cognitively sticky. Repetition only intensifies the effect, with the song replaying again and again inside our heads. Soon we can’t help but mumble the lyrics or hum the irresistibly catchy melody.

Feeding the Earworm: Why Tunes Get Trapped In Our Heads
Once a tune gets stuck on mental replay, an involuntary feedback loop fuels the earworm phenomenon. Even absent the external sound stimuli, auditory regions activate as if you were actually hearing the music. Yet other areas like the prefrontal cortex that normally moderate bottom-up sensory signals can’t seem to filter out the imagined melody.

Instead, visual and memory centres start firing in attempts to fill in the gaps, projecting associated imagery like music videos or the setting where you first heard the song. Unsuccessful efforts trying not to think of the tune essentially backfire, only strengthening neural pathways that evoke it. Like wiggling a loose tooth, you end up aggravating the earworm with each replay.

Underlying this process, the brain’s intrinsic connectivity likely enables songs to reverberate subconsciously within localised networks. Neuroimaging reveals the default mode network, comprised of interacting memory, auditory, and association regions, maintains intrinsic activity even at rest. This network involving musical memory circuits would provide prime real estate for earworms to take up residence as self-perpetuating mental background music.

Replacing Earworms: Using Neuroplasticity to Control Musical Imagery
While we can’t always control when or why songs get stuck in heads, we can leverage neuroplasticity to manage our mental soundtracks. The brain continually rewires neural connections in response to experience. We can thus train our minds to suppress unwanted earworms.

One strategy involves consciously rehearsing a new desired song. Try singing your favourite childhood nursery rhyme or reciting song lyrics that hold more meaning to you. Alternatively, engage fully with your present environment using all your senses – feel the breeze, notice smells and sights around you, have an engaging conversation with a friend. Distraction starves the earworm by shifting neural resources towards processing competing sensory inputs.

Over time, the brain will filter the intrusive tune into the background, allowing more adaptive musical imagery to take its place. You might still catch strains of a lingering melody now and then. But understanding the underlying mechanisms provides some reassurance that you can ultimately control your own mental radio station.

The next time you catch yourself spontaneously humming the same repetitive bars of the latest Billboard chart-topper, you’ll know the neuroscience behind the earworm wriggling into your brain. While we might not be able to prevent catchy songs from getting trapped in our heads, a little brain training can help ensure we don’t end up singing them for too long. Now, if you’ll excuse me, I have an earworm to replace – I’m off to listen to some Beethoven to clear my mental musical palette!