Buzz
You’ve probably heard the saying that you can’t always trust your eyes, and optical illusions—what Neil deGrasse Tyson refers to as "brain failures"—prove that. Turns out, you can’t always trust your ears either. Recently, a four-second audio clip took over the internet, sparking a debate over whether it said "Yanny," "Laurel," or even both. Audiologists suggest the clip contains two overlapping tracks with different frequencies. Scientists refer to this as an aural illusion, and it's just one example. Here are six more illusions that may cause you to question your hearing.
1. BRAINSTORM OR GREEN NEEDLE
How It Works: The video in question is from a 2014 YouTube toy review, uploaded by critic DosmRider. The review features a plastic space station from the Ben 10 collectible series. The set includes a docking station for action figures, which triggers different sounds when the figures are inserted. One of these figures, a crab-like character named Brainstorm, activates a loud sound of his name being called out when placed on the station. However, many listeners swore they heard the phrase "green needle" instead.
The clip features a variety of acoustic patterns—some that align with the term "green needle" and others that correspond with "brainstorm." Your brain’s expectations of the words you’ll hear, combined with the poor-quality audio, contribute to the effect. "When confronted with an unclear acoustic signal due to low quality or background noise, your brain tries to make the best match between what is heard and the anticipated word," Valerie Hazan, a professor of speech sciences at University College London, explained to The Telegraph.
2. SHEPARD TONES
The Illusion: In the video, you perceive a sound that seems like a single tone constantly rising. This effect is commonly used in movie scores by composer Hans Zimmer, known for his work in films like Dunkirk and Interstellar. The effect tricks our ears into hearing something impossible: a sound that appears to rise in pitch endlessly, without ever peaking or increasing in volume.
How It Works: The clip actually features three distinct sounds layered together—these are Shepard tones. Each sound is an octave higher than the one below it. When separated, as shown in this Vox video, the highest tone fades out, the middle tone stays steady, and the lowest tone grows louder. Since we’re always hearing two tones moving upward, we trick ourselves into believing that the combined three tones are rising constantly at a consistent pace. This illusion also works with downward-moving octaves.
3. CIRCLES, BEEPS, AND SENSORY CONFUSION
The Illusion: The first 15 seconds of this video showcase two multisensory displays. In the first, a single black circle appears on the screen, accompanied by a high-pitched beep. The exact same animation occurs again, but this time, two beeps accompany the appearance of another black circle. Although the animation is identical in both instances, some viewers perceive two flashing circles in the second display.
How It Works: Known as the sound-induced flash illusion, this trick exploits the way your brain sometimes uses other senses to interpret what your eyes are seeing. The additional beeps can lead you to misinterpret a single flash as two separate ones. Certain individuals may be more susceptible to this illusion. A 2012 study of 29 volunteers showed that almost all participants reported seeing the second flash in at least some trials. However, those with smaller visual cortexes—the part of the brain that processes visual information—were much more likely to experience the illusion than others.
4. THE MCGURK EFFECT
The Illusion: In the previous example, sound influenced what you saw. In this case, what you see alters what you hear. A man repeats the word "bah" over and over. Or does he? Turn off the sound and observe the shape of his mouth as he speaks. He’s actually saying "fah."
How It Works: First identified in the 1970s by researcher Harry McGurk [PDF], the McGurk Effect arises when auditory and visual signals don't match. The brain’s powerful drive to resolve this discrepancy can lead it to alter what you hear to match what you see.
5. SPEECH TO SONG
The Illusion: Diana Deutsch, a professor at the University of California, San Diego, is a leading expert in the psychology of music. In 1995, while editing an audio lecture, Deutsch repeatedly heard the phrase "sometimes behave so strangely" on loop. As it played over and over, the spoken words began to take on a musical quality, transforming from speech to song in her perception. This phenomenon has affected others in the same way. Watch the video above and notice how, despite the speaker not singing, the speech takes on a musical tone after a while.
How It Works: This experience is what Deutsch refers to as the speech-to-song illusion. Music relies heavily on repetition, and it appears that our brains attempt to create melodies from repetitive phrases or sounds. While the exact reasons for this phenomenon are not entirely understood, further research may offer insights into how our minds process and organize sensory information [PDF].
6. PHANTOM WORDS
The Illusion: When you hit play on the video above, your ears will be bombarded by loud, repetitive syllables. For the best effect, position yourself between two speakers, or use a good pair of headphones. As you listen, your brain may start identifying recognizable words or phrases. People who have experienced this have reported hearing words like "no brain," "window," "raincoat," "mango," and "Broadway."
How It Works: Ever looked at a bowling ball and thought the three holes on it resembled a human face? That's an example of pareidolia. This is a similar effect. Our brains are wired to seek patterns in what we see and hear. In the audio clip, there are two tracks, each containing ambiguous words. These sounds blend together and reach your ears as an incomprehensible noise. Listen long enough, and you'll start hearing "phantom words"—words or phrases that aren't actually there. Our brain, in its need for patterns, forces us to hear them.
This experiment is yet another of Diana Deutsch's ingenious creations. She discovered that the phantom words people hear tend to reflect their emotional state. For instance, individuals focused on their weight may hear food-related terms in the mix.
