TOPICS > Science

Searching for the Source of Phantom Sounds

BY Jenny Marder  February 3, 2011 at 11:27 AM EST

There is little consensus on what causes tinnitus, or ear ringing. Photo via Flickr Creative Commons

When Gloria Chepko was 4-years-old, she had a name for the ringing in her ears. She called it “the sound you hear before you hear something.” Now at age 66, the ringing still haunts her, disrupting her sleep and making her highly sensitive to loud noise.

Chepko has tinnitus, a hearing disorder characterized by a phantom sensation of ringing or buzzing in the ear. To her, it sounds like a high-pitched grasshopper, but more grating and more oppressive, faster and squeakier. “Sometimes it feels like it’s in the back of my head, not actually in my ears,” she said, and reached behind her ears to point, while mimicking the noise. “It sounds like this: wewewewewewe!”

Chepko is sitting at the kitchen table of her Loudon County, Va., home.The kitchen and living room are cluttered with wilderness books and nature photographs of lakes, canoes and lighthouses. Outside is a small garden, where she grows azaleas, rhododendrons, and pampas grass. Her neighbors are more conservative than she’d like – one complained about the color of her door; another called her rainwater barrels an eyesore. But despite these annoyances, the house has one thing – one big thing – going for it: it’s quiet.

And for Chepko, certain noises, like rap music and ambulance sirens, aggravate the tinnitus. So a quiet home is the difference between feeling constantly edgy and feeling okay, the difference between pain and no pain. “It’s not physical the way a headache is, but it takes a psychological toll,” she said.

Tinnitus was the number one service-related disability among veterans in 2010, according to the Veterans Administration. That means more veterans received disability compensation for tinnitus last year than any other disorder. Post-traumatic stress was a close second.

There is no treatment, and little consensus on what causes tinnitus. But Josef Rauschecker, a Georgetown University Medical Center neuroscientist, wants to change that. He has been studying patients like Chepko to better understand the physiological mechanisms responsible for tinnitus. He believes it is caused by a confluence of events:hearing damage combined with functional changes in the limbic system, the part of the brain responsible for both interpreting sound and regulating emotion.

Here’s how he explains it. All patients with tinnitus have some degree of hearing damage. But most people with hearing loss have a built-in mechanism that prevents them from hearing phantom sounds. He calls that mechanism an “intrinsic noise cancellation system.”  Within the brain’s limbic system, he believes, is a sort of switch that turns off the phantom sounds for most people. But when that switch is dysfunctional, tinnitus can result.

Rauschecker’s Georgetown office is full of maps from his travels and a wall covered in snapshots of himself and his colleagues, alongside a quote that he found in a Chinese fortune cookie: “Time is precious, but truth is more precious than time.” He found the quote to be particularly relevant for scientists. “I tell my students, it’s more important to get it right than to get it out quickly.”

A study published by Rauschecker and his team last month in the journal, Neuron found that patients with tinnitus were more likely to have structural changes in the brain’s prefrontal cortex along with hyperactivity in the nucleus accumbens, a region of neurons deep in the brain, known to play a role in pleasure, addiction, aggression and fear.

“The nucleus accumbens is the last station in the processing pathway,” Rauschecker said.“And it signals, ‘this is bad, bad, bad.’And the ventromedial prefrontal cortex that would normally make it go away is broken.”

For many patients, the tinnitus gets worse at times of high emotion or anxiety. Clinical depression rates are estimated to be more than twice the national average among tinnitus patients.

It’s a chicken or an egg question. “You might say, of course, people with tinnitus get depressed and they have trouble sleeping,” Rauschecker said. “We’re saying, no, it’s the other way around.Something is broken.”

It’s no surprise to Rauschecker that returning military veterans experience the condition at such high rates. “Soldiers in the field are exposed to not only loud noise exposure, but also stress,” he said. “They will most likely have hearing loss from loud noises in the field. And stress can lead to damage in the ventromedial prefrontal cortex, which would normally help them out and allow them not to get tinnitus.”

Richard Salvi, director of the Center for Hearing and Deafness at the State University in Buffalo, N.Y., is not convinced that stress is a root cause for all tinnitus patients.“The cases that don’t do a very good job explaining that are when a person goes to a loud concert or hits a nail with a hammer, and gets the tinnitus almost simultaneously, he said. “There’s no stress at that time.”

But Salvi does believe that there’s some kind of correlation between the two. “I’ve talked to a lot of tinnitus patients over the years, and many will tell me they get their tinnitus when they’re under tremendous stress,” he said, adding: “It’s extremely disruptive for many of these individuals. I have people call me up over and over again trying to get some sort of treatment.”

Salvi adds that the research may help answer one of the field’s biggest research questions: why tinnitus bothers some people with hearing damage and not others.

“I think the Rauschecker paper is novel in trying to perceive why some people hear tinnitus and some don’t,” Salvi said. “It’s like you’re listening to National Public Radio and the farther you get out of town, the more you turn up the radio, so you’re hearing static. Amplified signals like this are being sent up to the brain, and the brain has to decide whether to pay attention to them or ignore them.The paper’s hypothesis is that the nucleus accumbens is a gatekeeper that lets them get into our conscious perception.”

Rauschecker’s interest in tinnitus stems from his own battle with the disorder.Unlike Chepko, it’s not always present, but revisits him during times of exhaustion or stress.“In almost every patient, it varies with their emotional state.That’s one of the most important observations, and that’s what led us to this study,” he said.

He hopes to eventually work with doctors to develop treatment options for tinnitus patients, such as antidepressants or even deep brain stimulation. He also wants to study the role of neurotransmitters, like serotonin.

“The brain is such an amazingly smart system,” Rauschecker said.“So many things happen to us, and the brain is usually able to correct. It’s only when it breaks that we notice it’s broken.”

As for Chepko, she always hears the ringing, but the volume and intensity varies. She has a hard time pinpointing exactly what sets off her tinnitus. But it’s clear that it has a powerful influence over how she lives her life. She can’t go to baseball games or dance halls. At night, she pulls the pillow around her ears to block out external sound.

But certain things provide a welcome distraction. “Walking somehow distracts me, she said.“And anything in the water: animals, birds.” So she spends as much time outdoors as she can.

And nearly every year, Chepko and her husband fold up their kayaks, pack them into a backpack and head to North Carolina or Alaska or the Chesapeake Bay, to a place where she can be outside… to a place where the sound before you hear something is just a little less loud.