The Science of Aural Illusions: Why Your Brain Mishears Lyrics

New research provides further evidence that the human brain often just hears what it expects to hear.

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If you participated in the recent Laurel vs.Yanny viral phenomenon, then you already know that you can't always trust your ears. What you hear, when a certain word or phrase is uttered, isn't necessarily what the next person hears — or what the original speaker said.

According to a new neuroscience study published this week, we finally have a culprit for all the confusion. As usual, you can blame your brain — or a very specific part of it, anyway. The next time you mess up a song lyric, blame your left superior temporal sulcus.

The research, published in the journal Jneurosci, concludes that misperception of speech often results from a difference between what is said and what we expect to hear.

That's because the brain tends to use past experience when deciphering an ambiguous chunk of spoken language. If what was said sounds pretty close to something you've heard before, the brain will default to the more familiar reading when it translates linguistic input coming up through the ear canal.

To use a famous example from the realm of misheard lyrics: Jimi Hendrix's line “Excuse me while I kiss the sky” in his song “Purple Haze” is often misheard as “Excuse me while I kiss this guy.” That's because the brain is more familiar with the concept of kissing a guy rather than the sky.

This isn't just informed conjecture, either. The research team has hard data from brain scanning machines to back up the theory. Along with colleagues from the University of Cambridge and University Medical Center Hamburg-Eppendorf in Germany, lead researchers Helen Blank and Matt Davis deployed functional magnetic resonance imaging (fMRI) to monitor the brain activity of volunteer listeners.

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The research team presented participants with pairs of written and degraded spoken words that were either identical, clearly different, or similar-sounding. Reading and hearing similar sounding words — like kick followed by pick — led to frequent misperception.

The fMRI imaging found that the misperception was associated with reduced activity in the left superior temporal sulcus, the region of the brain responsible for processing speech sounds. The results provide new evidence for the theory of predictive coding, which suggests that a good deal of speech perception involves comparing what we hear with what we expect.

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These new findings could be used to improve treatment for age-related hearing loss and to better understand auditory hallucinations in disorders such as schizophrenia.

And in the meanwhile, they serve as a helpful reminder to not believe everything that you hear.