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Check out this art made in sand by Jim Denevan with no measuring aids. Then hope he comes here for a visit

Jim - St Petersburg, FL - didja get that? I’ll make you dinner and pie.

“Mosquito Ringtones” are high frequency cell phone ringtones available for download that are being marketed to kids and teens as the ring tones ADULTS CAN’T HEAR.

The premise:

Starting in early middle age, the human ear loses its ability to hear tones in the highest human-range frequencies (18-20 kHz). The older you are, the less likely you are to hear high frequency sounds. Also, more exposure to constant loud noise can make this affect worse. So if you jammed to the Rolling Stones when you were 17, or if you use a jackhammer all day - chances are you’re hearing is worse than mine!

Kids’ & teens’ ear drums are more flexible and their inner ear is more active, so they are capable of hearing higher frequency vibrations of sound. Talk to any audiologist you know and they will explain that natural adult hearing loss is particularly acute at higher frequency ranges.

The history:

The use of “Mosquito” to relate to high frequency sound geared towards specific age groups dates back to 2005 when a British inventor named Howard Stapleton was looking for a way to keep teenagers from loitering outside of shops at night. His product, “The Mosquito”,  was marketed as ultrasonic teenage repellent, similar to the already in use ultrasonic dog repellent. The product blasts a continuous high frequency sound wave (approximately 17.4 kHz), designed to discourage loitering teens from a storefront while leaving adult customers unaffected.

As is true with most good inventions, sooner or later someone used it for something other than its intended purpose. In this case, the high pitched tone has been converted into a sound that is downloadable - a cell phone ringtone that parents and teachers can’t hear - which is aptly named “Teen Buzz”. If you’re lucky, your teenaged daughter’s teacher isn’t 35 yet.

Read about it on NPR or the NY Times here. See if you can hear the ringtones here.