Although both hemispheres of the brain generally work in tandem, it has long been believed that the left hemisphere plays a larger part in the comprehension of language. But a recent study conducted with a whistle-speaking population in Northeast Turkey is challenging that assumption.
Though they also use spoken language, the 10,000 or so Turks who converse via this ancient language can communicate with each other from as far away as three miles via a series of whistles that, when strung together, sound like a bird's song. Since it's already known that the right hemisphere of the brain is important for appreciating music, researchers speculated that the lilting whistles' musical melodies might activate this region while also engaging the left hemisphere’s language centers.
To test this theory, Onur Güntürkün of Germany's Ruhr University Bochum asked 31 fluent whistlers in the tiny town of Kuşköy to listen to pairs of different spoken or whistled syllables played into the left and right ears simultaneously and report what they heard. Because the left hemisphere depends slightly more on sounds received by the right ear and vice versa for the right hemisphere, whichever ear the reported syllable was played into corresponded to the opposite engaged hemisphere. By comparing the rate at which each hemisphere was selected, researchers were able to determine that spoken syllables resulted in the right ear/left hemisphere dominating 75 percent of the time, a finding that's consistent with previous studies. But as the researchers suspected, the dominant hemisphere when reacting to whistles was split almost exactly evenly.
This sort of auditory test for neurological activity isn't all that precise. But the results, published in Current Biology, hint at larger issues worth investigating.
"They tell us that the organization of our brain, in terms of its asymmetrical structure, is not as fixed as we assume," Güntürkün told The New Yorker. "The way information is given to us appears to change the architecture of our brain in a radical way."
But researchers who want to study the whistled Turkish language—either for its neurological implications or its cultural value—will have to act fast. The age of texting is causing this unique language to die out. "You can gossip with a mobile phone, but you can’t do that with whistling because the whole valley hears," Güntürkün told New Scientist.
You know can't always believe your eyes, as optical illusions—or "brain failures," as Neil deGrasse Tyson calls them—make clear. It turns you can't always believe your ears either. Recently the internet went nuts over a four-second audio clip that sounded like "Yanny," "Laurel," or both. Audiologists contend that the clip has two distinct tracks laid on top of each other at different frequencies. Scientists call this an aural illusion—and it's not the only one. Here are six others that will make you doubt what you hear.
1. BRAINSTORM OR GREEN NEEDLE
The Illusion: Twitter users bored with the Yanny/Laurel question have been sharing this equally divisive clip. Some people think the garbled recording says "brainstorm," while others hear "green needle." Many have discovered that their thoughts can change the outcome. If you repeat the phrase "green needle" in your head, that's exactly what you'll hear when you listen to the clip. But if you've got "brainstorm" on your mind, then "brainstorm" is the term your ears are going to pick up.
How It Works: The video is a clip from a 2014 YouTube toy review. Uploaded by critic DosmRider, it's about a plastic space station from the Ben 10 collectibles line. The playset comes with a loading dock for action figures that trigger different sounds when they get plugged in. A crab-like character called Brainstorm is represented by one of these models. Put him on the station, and his name blares from the speakers. While listening to the soundbite, many people thought the toy was saying "green needle."
The clip contains a variety of different acoustic patterns—some of which are consistent with the term "green needle" while others match "brainstorm." Your expectations of which words you'll hear—coupled with the low-quality audio—do the rest. "When faced with an acoustic signal which is somewhat ambiguous because it is low-quality or noisy, your brain attempts a 'best fit' between what is heard and the expected word," Valerie Hazan, a professor of speech sciences at University College London, toldThe Telegraph.
2. SHEPARD TONES
The Illusion: In the above video, you hear what sounds like a single, perpetually swelling tone. A common fixture in the movie scores of composer Hans Zimmer, whose work you've heard in films like Dunkirk and Interstellar, this effect makes us believe that we're hearing the impossible: sounds whose pitch seems to rise endlessly without ever peaking or actually getting louder.
How It Works: The clip is in fact three separate sounds being played together—what are called Shepard tones. Each of these is an octave higher than the one beneath it. When separated into individual tones, as this Vox video explains, you can hear that the highest tone fades in volume, the middle one remains constant, and the lowest one increases. Because we're constantly hearing two upward-moving waves, we convince ourselves that the three-layered sound (taken as a whole) is growing higher and higher at a steady pace. It works for tones moving down in octaves as well.
3. CIRCLES, BEEPS, AND SENSORY CONFUSION
The Illusion: The opening 15 seconds of this video contain two multisensory displays. In the first, a lone black circle flashes onto the screen. This is accompanied by one high-pitched beep. You will then see the exact same thing happen again, with another solitary black circle popping into view. But this time, there will be two beeping sounds instead of one. Even though the animation is identical in both runthroughs, some viewers think they can see two flashing circles in that second display.
How It Works:Dubbed the sound-induced flash illusion by its discoverers, the trick plays on the fact that your brain sometimes consults other senses to figure out what your eyes are seeing. That's how the back-to-back beeps can fool you into mistaking a single flash for two separate ones. Some people might be especially vulnerable to the illusion. A 2012 study found that in a pool of 29 volunteers, nearly everyone reported seeing the second flash in at least a few trial runs. However, participants with small visual cortexes—a region of the brain which deciphers optical signals—saw it way more often than their peers did.
4. THE MCGURK EFFECT
The Illusion: In the previous entry, sound may have changed what you saw. In this one, seeing might change what you hear. A man says "bah" over and over. Or does he? Turn off the sound and see the shape his mouth makes as he speaks. He's actually saying "fah."
How It Works: First documented in the 1970s by researcher Harry McGurk [PDF], the McGurk Effect involves an incongruence between audio information and visual information. The brain's desire to reconcile these incongruent inputs is so strong, it can change what you hear to align with what you see.
5. SPEECH TO SONG
The Illusion: Diana Deutsch, who teaches at the University of California, San Diego, is an authority on the psychology of music. One day in 1995, Deutsch was editing an audio lecture she'd recorded. The sentence fragment "sometimes behave so strangely" was playing on a loop in her office. As she heard repeated over and over again, the phrase began to sound less like talking (which it was) and more like singing. It's had the same effect on other people. In the above video, notice how, after a certain point, this spoken-word recording picks up a musical quality, even though the speaker never actually sings.
How It Works: It's a phenomenon Deutsch has named the speech-to-song illusion. Repetition is a core component of all music, and it seems our brains try to create little melodies out of statements or sounds repeated to excess. How or why this occurs isn't completely understood. As future experiments dissect the illusion, psychologists may learn new things about how the mind organizes and processes the things it perceives [PDF].
6. PHANTOM WORDS
The Illusion: Once you click play on the video above, some bombastic, repeating syllables are going to hit your eardrums. For best results, place yourself between two speakers, but a decent set of headphones should also do the trick. Amidst this aural onslaught, your mind will probably identify some recognizable words or phrases. Test subjects who've listened to this have reported hearing words such as "no brain," "window," "raincoat," "mango," and "Broadway."
How It Works: Have you ever looked at a bowling ball and thought the three holes on its side resembled a human face? That's called pareidolia. Something like that is going on here. We're hard-wired to seek out patterns, both visually and aurally. There are two tracks in this audio clip, with each containing an ambiguous word or two. These sounds mix together in the air and then reach your ears as an unrecognizable racket. Listen long enough, and sooner or later you'll begin to hear "phantom words"—words or statements that aren't really being said. Since humans crave patterns, we force ourselves to hear them.
This experiment was another brainchild of Diana Deutsch's. She's found that the phantom words a person hears are liable to reflect their current mood. For example, weight-conscious test subjects might hear food-related terms.
One night in 2016, Michelle Myers—an Arizona mom with a history of migraines—went to sleep with a splitting headache. When she awoke, her speech was marked with what sounded like an British accent, despite having never left the U.S. Myers is one of about 100 people worldwide who have been diagnosed with Foreign Accent Syndrome (FAS), a condition in which people spontaneously speak with a non-native accent.
In most cases, FAS occurs following a head injury or stroke that damages parts of the brain associated with speech. A number of recent incidences of FAS have been well documented: A Tasmanian woman named Leanne Rowe began speaking with a French-sounding accent after recovering from a serious car accident, while Kath Lockett, a British woman, underwent treatment for a brain tumor and ended up speaking with an accent that sounds somewhere between French and Italian.
The first case of the then-unnamed syndrome was reported in 1907 when a Paris-born-and-raised man who suffered a brain hemorrhage woke up speaking with an Alsatian accent. During World War II, neurologist Georg Herman Monrad-Krohn compiled the first comprehensive case study of the syndrome in a Norwegian woman named Astrid L., who had been hit on the head with shrapnel and subsequently spoke with a pronounced German-sounding accent. Monrad-Krohn called her speech disorder dysprosody: her choice of words and sentence construction, and even her singing ability, were all normal, but her intonation, pronunciation, and stress on syllables (known as prosody) had changed.
In a 1982 paper, neurolinguist Harry Whitaker coined the term "foreign accent syndrome" for acquired accent deviation after a brain injury. Based on Monrad-Kohn's and other case studies, Whitaker suggested four criteria for diagnosing FAS [PDF]:
"The accent is considered by the patient, by acquaintances, and by the investigator to sound foreign.
It is unlike the patient’s native dialect before the cerebral insult.
It is clearly related to central nervous system damage (as opposed to a hysteric reaction, if such exist).
There is no evidence in the patient’s background of being a speaker of a foreign language (i.e., this is not like cases of polyglot aphasia)."
Not every person with FAS meets all four criteria. In the last decade, researchers have also found patients with psychogenic FAS, which likely stems from psychological conditions such as schizophrenia rather than a physical brain injury. This form comprises fewer than 10 percent of known FAS cases and is usually temporary, whereas neurogenic FAS is typically permanent.
WHAT’S REALLY HAPPENING?
While scientists are not sure why certain brain injuries or psychiatric problems give rise to FAS, they believe that people with FAS are not actually speaking in a foreign accent. Instead, their neurological damage impairs their ability to make subtle muscle movements in the jaw, tongue, lips, and larynx, which results in pronunciation that mimics the sound of a recognizable accent.
"Vowels are particularly susceptible: Which vowel you say depends on where your tongue is in your mouth," Lyndsey Nickels, a professor of cognitive science at Australia's Macquarie University, wrote in The Conversation. "There may be too much or too little muscle tension and therefore they may 'undershoot' or 'overshoot' their target. This leads to the vowels sounding different, and sometimes they may sound like a different accent."
In Foreign Accent Syndromes: The Stories People Have to Tell, authors Nick Miller and Jack Ryalls suggest that FAS could be one stage in a multi-phase recovery from a more severe speech disorder, such as aphasia—an inability to speak or understand speech that results from brain damage.
People with FAS also show wide variability in their ability to pronounce sounds, choose words, or stress the right syllables. The accent can be strong or mild. Different listeners may hear different accents from the speaker with FAS (Lockett has said people have asked her if she's Polish, Russian, or French).
According to Miller and Ryalls, few studies have been published about speech therapy for treating FAS, and there's no real evidence that speech therapy makes a difference for people with the syndrome. More research is needed to determine if advanced techniques like electromagnetic articulography—visual feedback showing tiny movements of the tongue—could help those with FAS regain their original speaking manner.
Today, one of the pressing questions for neurologists is understanding how the brain recovers after injury. For that purpose, Miller and Ryalls write that "FAS offers a fascinating and potentially fruitful forum for gaining greater insights into understanding the human brain and the speech processes that define our species."