One Friday morning in 2004, the people of Potters Bar were going about their daily business. Minutes from the center of town was 60-year-old Sylvia, a retired teacher, who was working in her house. All was well, apart from one thing: that wretched noise. The two notes that had started playing earlier that morning, which no-one else seemed to be able to hear. Sylvia had initially thought the radio must be playing, but a quick search proved that not to be the case. Fairly fearful of the strange new noise, which got louder throughout the day, Sylvia went to bed, hoping it would be gone by morning.
She woke up to find the noise was still there. It droned on and on, dah de dah de dah de. Over weeks, the notes changed, then developed, and months later finally became full blown musical hallucinations—tunes that were constantly in the background, sometimes so loud that they drowned out normal conversation.
“Please ignore her for a moment,” Sylvia says, as she welcomes me into the house. She’s talking about the golden Labrador sitting quietly in the hall. Sookie is Sylvia’s new hearing dog. “Good girl,” she says, to the dog. “Now you can go say hello.” Sookie bounds over to me and sticks her nose straight into my pocket. “She thinks you may have treats,” Sylvia says. “It’s always worth a try.” Sylvia needs a hearing dog because she is deaf. She finds it difficult to hear speech, and real music sounds awful, distorted by damage caused by an ear infection that caused profound hearing loss several years earlier.
Sylvia’s husband, John, waves hello, while we walk past a grand piano and through to a bright conservatory at the back of the house. I sit down on a wicker chair, while Sylvia serves up tea and biscuits. She takes me back to the Friday morning that it all started. She’d had tinnitus and hissing for a number of years previously. But this was something new. It was the notes C and D going back and forth, she says. “It was very slow at first. I remember thinking, ‘Oh I don’t want that, think about something else.’ The notes grew from there. I’ve never had quiet since.”
Gradually over weeks, the notes developed into short phrases that would repeat over and over. Before long they were complete tunes of the music she loved before she lost her hearing. “What kinds of tunes do you hear most often?” I ask.
“It’s mostly classical music, short excerpts. When I could hear properly, I didn’t tend to listen to much else.” Even as we sit talking—through the help of a microphone and lip reading—Sylvia’s tunes are playing in her head. If they ever recede, which they sometimes do when she’s focused on a piece of music or concentrating on speaking, they are replaced by a constant B flat tone and the hiss of tinnitus.
“Do they resemble any particular instrument?” I ask.
“They’re a cross between a wooden flute and a bell,” she says. “It’s really strange, you’d expect to hear a sound that you recognize, maybe a piano or a trumpet, but it’s not like anything I know in real life.”
“But it sounds like a real noise?”
“Yes, it’s not as if you imagine a tune in your head, it’s like listening to the radio. It manifests as real sound.”
Soon after her hallucinations started, Sylvia did something very constructive: She wrote them down, keeping a record in a manuscript book of all the tunes that would come and go. She has the rare talent of perfect pitch, which allows her to hear any note and know exactly which note is being played.
She brings the manuscripts to the conservatory for me to read. Some of the pieces are made up of random notes, never going anywhere particular. Other hallucinations resemble short sections of recognizable tunes—I recognize a passage from the traditional Scottish folksong, “My Bonnie Lies Over The Ocean.”
Seeing her hallucinations on paper highlights their repetitiveness. There are pages of notes that wind up and down, up and down. They are like this for most of the day, Sylvia says. Years of teaching math allowed her to make to a quick mental calculation: “If it’s just two or three notes, then they can take a second to play before they repeat,” she says, “so that's what? Hearing the same tiny tune about 86,000 times a day?” Sylvia tells me that early on in the evolution of her hallucinations, words began to put themselves to the tunes.
“I did my upmost to prevent that happening,” she says, “and I managed to make it stop.” I ask her why. “I didn't want that happening. I didn't want words coming into my mind. It just felt a bit close to schizophrenia.”
She’s right, of course—hearing voices that are not there is often considered a sign of mental illness. No one knows this better than David Rosenhan, a professor emeritus at Stanford, who in 1973 got himself, and seven other completely healthy friends admitted to the mental ward of hospitals across the US. The point of his experiment was to question the validity of psychiatric diagnosis, but they hadn't expected it to be so easy.
Rosenhan and his colleagues each phoned a hospital complaining of hearing voices. The rest of their medical history and any other life stories were all true. All eight were admitted—seven were diagnosed with schizophrenia, one with manic-depressive psychosis. As soon as they entered the hospital they said their hallucinations had disappeared. It was then up to each individual to convince the staff to discharge them—a task that took between seven and 52 days.
In fact, most hallucinations are not associated with schizophrenia. When John McGrath, a professor at the Queensland Brain Institute in Australia, analyzed interviews from more than 31,000 people from 18 different countries, he discovered that hallucinations were fairly common in all age groups. When participants were asked whether they had ever experienced a hallucination, such as hearing voices that other people said did not exist, five percent of men, and 6.6 percent of women answered yes.
I ask Sylvia whether she tells other people about her hallucinations. “No, I don’t talk to many people about it. Very early on, I was taught that, as sound travels up to the brain, it picks up emotions that go with that sound. In other words, if I became constantly irritated by them, the sounds would always cause irritation. If I told them they were unimportant, they would stay insignificant. So I took a conscious decision to belittle them, and not talk to other people about them. I don’t want them to garner an importance. It was the best advice I could have been given—it’s allowed me to live with them.”
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The word hallucination also has a mental health connotation, she says, a bad flavor. “Some of my best friends know about it, but we don’t talk about it.” She smiles. “Sometimes I go, ‘oh, shut up’ and they know what I’m talking about, but they can’t possibly put themselves in my shoes.”
She glances at John as he pops his head into the conservatory. “John, bless him, is a real support in every sort of way, but even he has no idea how dramatic this sound is that’s going on all the time. It gets in the way of his conversation with me. I mishear what he says so much of the time. Sometimes I think he’s said something very funny and he didn’t say it at all. He’s very understanding, but no-one can have any idea what this is like unless they’ve experienced it for themselves.”
In fact, there is a way that you can experience something similar for yourself, safely at home. All you need is a table tennis ball, some headphones and a bit of tape. Cut the ball in half and tape each segment over your eyes. Sit in a room that is evenly lit, find some white noise to listen to over your headphones, sit back and relax.
Called the Ganzfeld technique, this kind of sensory deprivation has been used to investigate the appearance of hallucinations for decades. In a paper published in the journal Cortex, Jiří Wackermann at the Institute for Frontier Areas of Psychology and Mental Health in Freiburg, Germany, describes some of the hallucinations that occurred in volunteers trying out the technique.
“For quite a long time there was nothing except a green-greyish fog,” said one participant. “It was really boring, I thought, ‘ah, what a nonsense experiment!’ Then, for an indefinite period of time, I was ‘off’, like completely absent-minded. Then, all of a sudden, I saw a hand holding a piece of chalk and writing on a blackboard something like a mathematical formula. The vision was very clear, but it stayed only for a few seconds and disappeared again… it was like a window into that foggy stuff.” Later, she saw a clearing in a forest and a woman who passed by on a bike, her long blonde hair waving in the wind.
Another participant felt like she and a friend were inside a cave. “We made a fire. There was a creek flowing under our feet, and we were on a stone. She had fallen into the creek, and she had to wait to have her things dried. Then she said to me: ‘Hey, move on, we should go now.’”
As I sit back in my own living room, ping-pong balls strapped to my face, I feel much the same way as that first participant. Nothing happened for at least 30 minutes, other than a myriad of random thoughts and waves of sleep. Just as I was wondering whether I should give up, I saw an image coming out from what seemed like a window full of smoke. It was of a man lying curled up next to me. He bent his elbow in this strange way as if presenting it to me. It appeared for a few seconds then disappeared. It certainly differed from a dream, or a random image plucked from my imagination. It was an intriguing demonstration of what can occur when our senses are impaired. But why does it happen?
“The brain doesn’t tolerate inactivity,” said Oliver Sacks, when I spoke to him about this back in 2014. “It seems to respond to diminished sensory input by creating autonomous sensations of its own choosing.” This was noted soon after the Second World War, he said, when it was discovered that high-flying aviators in featureless skies and truck drivers on long, empty roads were prone to hallucinations.
Now researchers believe that these unreal experiences provide a glimpse into the way our brains stitch together our perception of reality. Although bombarded with thousands of sensations every second of the day, your brain rarely stops providing you with a steady stream of consciousness. Think about all the sounds, smells, and tactile sensations that you can sense right now. Noise from the outside world, the tightness of your socks. Processing everything that you experience in the world all of the time would be a very inefficient way to run a brain. So instead, it takes a few shortcuts.
Let’s use sound as an example: When sound waves enter the ear, they are converted into electrical messages by receptors within the ear canal and transmitted to the brain’s primary auditory cortex. This part of the brain processes the rawest elements of sound, such as patterns and pitch. From here, the signals get passed on to higher brain areas that process more complex features, such as melody, key changes, and emotional context.
Instead of relaying every detail up the chain of command, the brain combines the noisy signals coming in with prior experiences, to generate a prediction of what’s happening in the world.
If you hear the opening notes to a familiar tune, for instance, you expect the rest of the song to follow. That prediction is passed back to the lower regions, where it is compared to the actual input, and to the frontal lobes, which perform a kind of reality check, before it pops up into our consciousness. Only if a prediction is wrong does a signal get passed back to higher areas, which adjust subsequent predictions.
You can test this for yourself: Anil Seth, a cognitive and computational neuroscientist at the University of Sussex, suggests listening to sine-wave speech, a degraded version of a speech recording. The first time all you’ll hear is a jumble of beeps and whistles. But if you listen to the original recording and then switch back to the degraded version, you will suddenly be able to make out what is being said. All that has changed is your brain’s expectations of the input. It means it now has better information on which to base its prediction. “Our reality,” Seth says, “is merely a controlled hallucination, reined in by our senses.” Or, as psychologist Chris Frith once put it: “A fantasy that coincides with a reality.”
This idea is consistent with what was happening to Sylvia: Although her regular hearing is distorted, familiar music can sometimes suppress her hallucinations for brief periods of time. In 2014, Timothy Griffiths thought he might be able to use this to support the prediction model of hallucinations.
“The main obstacle to studying hallucinations and why they arise has always been an inability to control them. Sylvia gave us a chance to switch them on and off,” he says.
Griffiths and his colleagues had Sylvia come into their lab and lie down in a machine that analyzed her brain waves—the cyclic flow of electrical activity around the brain. While the machine was analyzing her brain activity, Griffiths’ team played Sylvia various passages from a familiar Bach concerto. Sylvia rated the intensity of her hallucinations every 15 seconds throughout the study. At the time of the experiment, her musical hallucinations happened to consist of sequences from Gilbert and Sullivan’s musical HMS Pinafore. Immediately following the Bach, her hallucinations were silent for a few seconds, gradually increasing in volume until the start of the next excerpt. It was this that allowed Griffiths to measure her brain activity without the hallucinations, and then with them.
Sylvia’s brain scans showed that during her hallucinations, regions of the brain that process melodies and sequences of tones were talking to one another just as they might if she was listening to real music. Yet because Sylvia is severely deaf, they were not constrained by the real sounds entering her ears. Her hallucinations are her brain’s best guess at what is out there.
This theory also explains why listening to some kinds of music can stop Sylvia’s hallucinations. When she is concentrating on Bach, something she is familiar with, the signal entering her brain is much more reliable, and that constrains the aberrant conversation going on in higher areas—this then reconciles itself to what is actually happening in the real world.
This notion of hallucinations as errant predictions has also been put to the test in completely silent rooms known as anechoic chambers. At Orfield Laboratories in Minneapolis, Minnesota you can find such a chamber, dubbed “the quietest place on earth.” The chamber is actually a pitch-black room built inside a room, built inside another room. It has three foot thick walls of steel and concrete and is lined with jagged padding, designed to absorb what’s left of any tiny sound. Once inside, you can hear your eyeballs moving and you skin stretching across your skull. People generally start to hallucinate within 20 minutes of the door closing. But what’s the trigger?
I asked Oliver Mason, a clinical psychologist at University College London who specializes in sensory deprivation. There are two possibilities, he says. One is that sensory regions of the brain occasionally show spontaneous activity that is usually suppressed and corrected by real sensory data coming in from the world. In the deathly silence of an anechoic chamber, under the influence of the Ganzfeld technique or in the case of a permanent lost sense, the brain may make predictions based on this spontaneous activity that then run riot. The second possibility is that the brain misinterprets internally generated sounds. In an anechoic chamber, for instance, the sound of blood flowing through your ears isn’t familiar, so it could be misattributed as coming from outside you. “Once a sound is given significance, you’ve got a seed,” Mason says, “a starting point on which a hallucination can be built.”
Not everyone reacts in the same way inside an anechoic chamber. Some people don’t hallucinate at all. Others do, but realize it was their mind playing tricks. “Some people come out and say, ‘I’m convinced you were playing noises in there,’” Mason says. This was something I was puzzled about: Why did Sylvia hear hallucinations, when others with hearing loss did not? When I asked Mason about this, he told me there were several possibilities. Finding out the answer is incredibly important, he says, because it could reveal why some people are more prone to the delusions and hallucinations associated with mental illness.
We know that electrical messages passed across the brain are either excitatory or inhibitory—meaning they either promote or impede activity in neighboring neurons. In a recent unpublished experiment, Mason’s team analyzed the brain activity of volunteers while they sat in an anechoic chamber for 25 minutes. Those who had more hallucinatory sensations had lower levels of inhibitory activity across their brain. Perhaps, Mason says, weaker inhibition makes it more likely that irrelevant signals suddenly become meaningful.
People with schizophrenia often have overactivity in their sensory cortices, but poor connectivity from these areas to their frontal lobes. This might mean that the brain makes lots of predictions that are not given a reality check before they pass into conscious awareness, says Flavie Waters, a clinical neuroscientist at the University of Western Australia in Perth.
The knowledge that hallucinations can be a byproduct of how we construct reality might change how we experience them. In his later years, Sacks himself had become blind in one eye and had severe vision loss in the other. When he played the piano, he noticed that he would occasionally see showers of flats when he was looking carefully at musical scores. “Why they are flats, not sharps I don't know,” he said. He also hallucinated letters and the occasional words. His hallucinations didn't bother him, he said. “I have long since learned to ignore them, and occasionally enjoy them. I like seeing what my brain is up to when it is at play.”
Recently, Sylvia’s musical hallucinations have become much quicker, so that the notes go at a faster pace. They’ve also become louder. Now, she says, her hallucinations have developed so much that if she practices a Mozart sonata on the piano and then stops, the whole of the first movement will play in her mind. She says it’s like having one’s own internal ipod. It has its downsides—Christmas can become a nightmare for Sylvia: “They’ll be carols in all the supermarkets, so I’ll get fragments of those playing over and over—“it will drive me mad.”
Interestingly, words have also started to influence her hallucinations. The previous day, Sylvia had been reading and the word “abide” was on the page. Suddenly the hymn “Abide With Me,” started to play on Sylvia’s internal iPod. Images can also trigger songs: When she was in a toy shop with her granddaughter, she caught sight of a jester with bells hanging off its hat. Suddenly, “When That I Was And A Little Tiny Boy” started playing—the jester song from Twelfth Night.
She says she has also begun to get a modicum of control over her hallucinations. That morning, for example, she had gone swimming. The wax earplugs make everything silent, which makes the tunes in her head even more obvious. “It was going ‘yada da bomb bomb, yada da bomb bomb,’” she says. “I didn’t want that going on all the time I was swimming, so I pitched out loud a note that was a semi-tone up from what was playing to conflict with it. This made the tune hesitate. It sometimes takes a long time, but I can often make it change. I can also change it by singing another tune that I’d prefer to hear. Sometimes it works, sometimes it won’t. Sometimes it changes for a bit and then reverts back to original annoying few notes—it’s like a stubborn child in there, saying, ‘no, I want to play this’.”
I ask her if she ever has a period of silence.
“No, never,” she replies.
“Do you ever feel like you can tune into your own private radio and enjoy what you’re hearing when it’s a tune that you like?”
Sylvia thinks about this for a while. “I’ve been terribly careful not to let the tunes pick up any emotion, so that they don't constantly make me emotional,” she says. “I mean, they do still make me irritable. Sometimes I feel as if I haven't fully rested when I wake up. Sometimes it's really intrusive when they start playing before you've even found your slippers. But perhaps that's just me being an irritable old woman! But I don’t mind it so much when it's a full tune that I recognize.” She smiles. “I laugh at it a bit. I listen to it. I marvel at it. I do my best not to sing to it in case it reinforces it.”
She pauses. “But then it contracts. It always contracts. It might play two or three times and then it gets shorter and I realize it’s only the first two pages, or the first two lines of the tune and eventually just two or three notes again. That's the point when you can truly imagine being driven mad by it. Just dah di dah dah dah, dah di dah dah dah, dah di dah dah dah, dah di…”
I leave Sylvia’s later that afternoon amazed at her control, resilience, and good humor over what could easily have become a soul-destroying condition. Society teaches us to be fearful of those things that are not present in the world, to associate seeing and hearing things that no-one else does as a sign of mental unrest. Sylvia proves that this need not be true. We shouldn’t be afraid to fight this misunderstanding, to speak out when we experience things a little unusual. It is possible that we are all hallucinating all of the time—some of us are just more aware of it than others.
From the book UNTHINKABLE: An Extraordinary Journey Through the World's Strangest Brains. Copyright © 2018 by Helen Thomson. Reprinted by permission of Ecco, an Imprint of HarperCollins Publishers.
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