A sound designed to make youths flee

British inventor's crowd-control device gains popularity on both sides of Atlantic

You mean that piercing pulse that jumps on the eardrum and demands that I run far, far away?

Yes, I hear that.

It's another perk of youth, I suppose.

- Nancy Johnston

... Can't hear a thing

Graying hair, muscle aches and now this - the inability to hear the Mosquito device: The indignities of old age keep coming.

I plugged in the machine at home, about the size and weight of an old rotary telephone (now I am dating myself). I held it within inches of my ear, and couldn't hear a thing. Meanwhile, my 17-year-old daughter, unaware of what I was doing across the kitchen, shrieked. My 13-year-old son heard it, but didn't seem nearly as anguished as my daughter. She seemed in physical pain even though the Mosquito had only been on for a few seconds. The effect was mind-boggling, like an aural dog fence that grown-ups could pass through with no effect.

At work, some colleagues roughly my age held the device to their head like a sea conch and admitted they, too, couldn't hear a thing. One office wag suggested it could be marketed as a tool for corporations seeking early retirement of older employees: If you can't hear the sound, you're eligible for the buyout.

- Andrew Ratner

Why adults can't hear it

Adults generally can't hear the Mosquito device due to presbycusis, an age-related decrease in hearing acuteness that's most pronounced with high-pitched sounds.

The National Institute on Deafness and Other Communication Disorders says that the process is gradual. People who have presbycusis may not realize that their hearing is diminishing. The condition most commonly arises from changes in the inner ear, but can also result from changes in the middle ear or along the nerve pathways leading to the brain, the institute says.

Other contributing factors are the cumulative effects of environmental noise, loss of hair cells (sensory receptors in the inner ear) and side effects of some medications.

-Joe Burris