Static Electricity can play havoc
with cochlear implants
Plastic playground slides can
zap hearing devices and force kids to play in silence
As reported by Eric Hand
St. Louis Post-Dispatch
Six-year-old Taylor Zinderski slid down a plastic slide and slipped
It was October at a church playground.
Taylor, deaf for almost two years, ran to her father. She told him
her cochlear implant -- an electronic device that lets her hear
-- had suddenly fizzled.
It had been zapped by a static electric shock. Chris Zinderski hadn't
switched off his daughter's implant because he didn't believe that
static could really be a problem.
"Now I've learned my lesson," he said.
Plastic slides studied
The shock didn't ruin Taylor's implant,
but it did require an inconvenient trip to an audiologist. Static
electricity is so much of a worry and hassle for the deaf that Washington
University electrical engineer Robert Morley has a grant to study
one of its main sources: plastic playground slides.
As playground slides evolve from metal to durable, cheap and colorful
PVC plastic, deaf children face a sad choice: Don't play, or turn
off their implants and play without sound.
Some playgrounds, such as new "all inclusive" ones, have
deliberately included metal slides, which don't produce static electricity.
But many others don't -- including some that are supposed to be
accessible to disabled children.
"Every time I look, there's another we can't go to," said
Peg Jones, the mainstream coordinator at St. Joseph Institute for
the Deaf in Chesterfield, Mo.
In the name of science
Morley, who helped pioneer digital
hearing aids, got a small federal grant to study the issue. His
first task: See how much static a slide can make. He sent his two
daughters down St. Louis-area plastic slides hundreds of times,
wearing different clothes.
Static electricity occurs when a "positive" material sheds
electrons by rubbing a "negative" material that attracts
them. Good static-producing combinations include wool and PVC plastic,
hair and rubber, and skin and polyester. Cotton, paper and steel
The resulting charge on both objects can dissipate slowly in humid
air, or cause a shock if it touches something that is grounded,
such as a person, a car -- or the metal pole that Morley had his
daughters touch after each slide.
Humidity is a factor
The type of clothes and length of the
slide didn't matter much. But humidity did. In the cold, dry air
of winter, Morley's daughters achieved charges of about 10,000 volts.
Morley says that in the dry air of Tucson, Ariz., a colleague measured
20,000 volts after a slide.
In coming months, he will apply those voltages to test implants,
which are rated to withstand 8,000 volts, according to Doug Miller,
an engineer with Cochlear Americas, one of the manufacturers of
Cochlear implants can cost more than $50,000. They require a delicate
surgery to insert a wire into the snail shell-shaped cochlea. A
hearing aid outside the ear picks up sound and converts it to an
electrical signal that is broadcast through the skin to the internal
device, which electrically stimulates the auditory nerve.
Miller and Morley both stress that static electricity is not a threat
to the internal part of the implant. It can only zap the external
equipment and force a trip to the audiologist for recalibration.
Miller says it will soon be a nonissue, as deaf people move to newer
implants that can withstand more static. New rules will require
a rating to 15,000 volts, and most companies test the devices at
even higher levels, he says.
Spray away the static
But until then, each room at the Moog
Center for Deaf Education in St. Louis County will keep a bottle
of diluted fabric softener for spraying down staticky kids and carpets.
On a cold November morning, family school director Betsy Brooks
watched for signs of static.At recess out on a wood and metal playground,
the children played with their implants turned on. Taylor sailed
down the metal slide, her mop of curly blond hair bouncing in the
air. Jones feels sorry for the children who have to turn their implants
off."It's a completely different experience to go down the
slide without the wind and the 'whee,' " she said.
Allowing the children to wear our new Static
Friendship Bracelet* may help this problem or make it become