Tucked inside the air traffic control tower in Portland, Maine, Samantha
Bassett was busy making sure planes didn’t crash into each other. All
systems seemed normal that day in May 2014. Aircraft pinged their
positions on radar while a constant and chaotic barrage of updates and
requests flowed through her headset.
Then, out of nowhere, a burst of interference screamed into Bassett’s
right ear. Those in the business call this phenomenon “getting sidetoned.”
It can happen when lightning strikes, equipment malfunctions, or radio
signals cause feedback like you might hear at a rock concert.
Bassett simply took off the headset, switched on speaker mode, and kept
working. The planes must go on, after all.
Within the hour, though, Bassett got a headache and grew nauseous.
She ended up going to see her doctor.
She knew something was wrong, but the results from an audiogram—a
test of how well the ear picks up sound across different frequencies— looked
normal. She could detect soft high and low tones, and the ones in between.
“You don’t have any hearing loss,” her doc told her. “You seem fine.”
But Bassett wasn’t fine. The nausea went away quickly, but loud environ-
ments continued to induce headaches. Her interactions started to change.
In bars and restaurants, she couldn’t track the chatter. “I could see people
talking, I saw their lips moving, and I knew sound was coming out,” she
says. But she couldn’t decipher what that sound meant. She began to smile
and nod a lot. At work, when plane traffic got heavy, she had to concentrate
to interpret what she heard. “Before this happened, I could follow three to
four conversations at once—because that’s what air traffic controllers are
trained to do,” she says. Now, everything seemed to become harder.
For the next few years, Bassett continued to see specialists and search
for answers, until she learned about a recently discovered phenomenon
called hidden hearing loss. Usually, we expect that people’s sonic percep-
tion degrades because the receptors that detect sound get damaged and
can’t pass the signals onward toward the brain. In a groundbreaking 2009
mouse study, though, Harvard auditory neuroscientists Charles Liberman
and Sharon Kujawa found that sometimes the problem resides in another
part of the ear: The receptors are fine, but some of the synapses that should
transmit the messages have withered. As Liberman sees it, the micro-
phone is good, but the stereo jack is damaged.
A person with this sort of damage can detect quiet sounds just fine,
so audiograms don’t register any anomalies. But when surrounded by
noise—where chitchat bounces off minimalist walls, machinery rumbles
against a colleague’s instructions, or music blares
from speakers—they can’t pick out the sounds they
care about. Some individuals with these symptoms
experienced a single blast, as Bassett did. Others
were exposed to lower decibel levels over time,
like listening to their orchestra practice, working in
an engineering lab, or even mowing the lawn every
Saturday. Some take prescription drugs that harm
the delicate ear. Some have autoimmune disorders.
Some are in their 20s. Some are in their 80s. The trig-
gers vary, but the results appear the same: People can
hear, but when it’s noisy, they can’t understand.
There are no statistics on how many might be af-
fected, or exactly how much exposure would make
you susceptible. Doctors can’t point to a single living
person and definitively say they have hidden hearing
loss. That’s because they can’t dissect your head, re-
move your inner ear, and see that your synapses are
screwed up—which is currently the definitive biolog-
ical test for the disorder. So the victims of this aural
anomaly are, like Bassett, told repeatedly there’s
nothing wrong. That’s why Kujawa, Liberman, and
international groups are racing to understand the
condition. Their research is leading the biotechnol-
ogy industry toward treatments that could reverse
the damage by coaxing synapses to regrow and give
people back their normal, clamorous lives.
It’s a scientific path that matters to everyone in the
modern world, unless they live under very quiet rocks.
We’re exposed to more noise than ever. And it might
be hurting us more than we realize.On a too-hot summer day in July, Kujawa sits in
her office at Massachusetts Eye and Ear, a Harvard
teaching hospital housed in, as she describes it,
“a building that’s kind of been pasted together,”
with a third floor that connects to the others only
in some places. A bookshelf displays, perhaps lower
down than you’d imagine, the etched-glass cylinder
of her 2017 Callier Prize in Communication Disor-
ders. Out the window, the Charles River silently
flows. “Patients tell us all the time that they don’t
hear as well as they used to,” Kujawa says, “and
then they go into the clinic, and audiologists do the
usual things and say, ‘You’re good.’” The patients,
she says, “know they’re not good.”
No one really knew why until Kujawa and Liber-
man discovered hidden hearing loss, causing what
many in the field call a paradigm shift— changing
how researchers think about the ear’s inner workingsTUCKEDON APG 44POPSCI.COM · WINTER 2019