A sound as ordinary as clinking ice cubes “feels like someone is stabbing me in my ears,” Cindy Redmond tells PEOPLE

14-Year-Old Girl Blasted with Air Horn Speaks Out: 'I Feel Like I’m Being Stabbed in the Ear'

Sitting at the kitchen table at a friend’s house, Cindy Redmond made the mistake of chatting on her cellphone.

Her friend’s stepfather instructed her to hang up. She did so at his second request. Still annoyed, he blasted her with an air horn.

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That careless action forever changed Cindy’s life.

An air horn at close range hits 130 decibels or more — loud enough to cause auditory destruction.

Cindy, who lives in Wilmington, Delaware, felt “off” in English class the next day. Her teacher’s voice seemed painfully loud. Cindy went home sick. That was a year ago.

Her ear pain grew so intense that she was never able to return to school.

Cindy, now 14, suffers from hyperacusis, a rare hearing disorder sometimes called noise-induced pain. Deep within her ear canals, she feels a constant fiery pain and pressure.

A sound as ordinary as clinking ice cubes “feels like someone is stabbing me in my ears,” she tells PEOPLE.

Image zoom Cindy and Laurie Redmond Courtesy of the Redmond family

Cindy is now raising funds for the nonprofit Hyperacusis Research, which supports scientific research into noise-induced pain. (The Redmonds have decided not to pursue any legal action against her friend’s family, since the stepfather has a family of six to support.)

Cindy’s page, at Cure4Cindy.org, notes that an acoustic injury can result from one loud burst of noise or from cumulative exposure over time, which includes loud music and concerts.

Image zoom Courtesy of the Redmond family

“People are unaware of the enormous destructive power of sound,” says Bryan Pollard, president of Hyperacusis Research.

Cindy should have started 9th grade at Brandywine High School last fall. “The school couldn’t make accommodations to soundproof her academic world,” her mother, Laurie Redmond, tells PEOPLE.

Instead, when Cindy’s pain is manageable, she goes once a week to a special school with no shrill bells, no slamming lockers and just a few other kids.

Image zoom Cindy Redmond Courtesy of the Redmond family

Otherwise, she stays mostly in the quiet house she shares with her mother and some pets. Even watching television — with its unpredictable volume — is tough on her ears.

“Overexposure to sound does not always lead to conventional hearing loss,” says M. Charles Liberman, an otology professor at Harvard Medical School, who heads a hearing lab at the Massachusetts Eye and Ear Infirmary.

Instead, some people suffer the opposite: Noise becomes not too soft, but painfully loud, according to Cure4Cindy.org.

Descriptions of the ear pain are remarkably consistent — a burning feeling like molten metal along with a knifelike stab.

“It’s a sensation that most of us have rarely, if ever, experienced,” Liberman said. According to the latest research, one culprit may be pain-sensing nerve fibers deep within the inner ear.

When the noise stops, the pain continues, lingering or even worsening. Confusingly, most audiology tests appear normal.

Image zoom Courtesy of the Redmond family

One recent day, when Cindy attempted a visit with friends, one girl squealed.

“Cindy started sobbing from the pain,” Laurie says. “Her friends insisted she was faking her injury, or her face would have turned more red.”

With no blood and no bandage, there is no sympathy either, says her mother. “I hear these stories over and over. She cries herself to sleep. My heart breaks for her.”

Cindy made the rounds of doctors, who were unhelpful. Pain medication had little effect. She tried a sound therapy that employs mild broadband noise but it made her worse and sparked tinnitus, or ringing in the ears.

Image zoom Cindy Redmond Courtesy of the Redmond family

With no choice, Cindy copes by using earplugs and protective earmuffs, the kind worn by airport baggage handlers.

But ear protection makes it hard to communicate and isn’t always enough to buffer the pain. Even a supermarket trip is filled with screeching checkout beeps and loudspeaker announcements that pierce right through.

Though her home is generally quiet, the threat of noise remains. Cindy’s beloved dog, Sadie, sometimes barks when excited. One misstep in the kitchen, and pots clang like cymbals.

“Having hyperacusis is like walking into a bear’s cave,” Cindy says. “You don’t know what noise is coming your way next. It’s a living nightmare.”

Cindy’s mother, laid off from a job in the mortgage field, is currently working retail, with a flexible schedule that lets her spend more time with Cindy.

Image zoom Cindy Redmond Courtesy of the Redmond family

“I used to worry that Cindy had the right friends and was taking the right classes to get into college,” Laurie says. “Now I worry that she has no friends. I don’t know how she’s going to finish high school. I have no idea what her future holds.”

Until Cindy’s injury, the Redmonds had never heard of hyperacusis.