Static poses risk to deaf children

Six-year-old Taylor Zinderski slid down a plastic slide and slipped back into silence.

Taylor, deaf for almost two years, ran to her father to tell him her cochlear implant -- an electronic device that lets her hear -- had suddenly fizzled.

It had been zapped by a static electric shock.

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.

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 are neutral.

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.

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, 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 the devices.

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.

© Copyright 2005 Globe Newspaper Company.

•	Static poses risk to deaf children Boston Globe, Monday, Dec. 12, 2005 Byline: Eric Hand, St. Louis Post-Dispatch

•	Static from plastic slides can drop deaf children back into silence Fort Wayne News Sentinel (IN), Friday, Dec. 9, 2005 Byline: Eric Hand, St. Louis Post-Dispatch

	Story also ran in 5 others:  Knight Ridder/Tribune News Service, St. Louis Post-Dispatch, 4HearingLoss.com (NY), Wilkes Barre Times-Leader (PA) and The Olympian (WA)