Research has revealed that kids can hear high-pitched noises, which adults can't. The House Ear Institute in Los Angeles has said that most adults' ability to hear high frequency noises disappears in "early middle age."
A Welsh security company has decided use this difference in hearing ability. They invented a high-pitched noise that would irritate teenagers but wouldn't be heard by adults. This devious invention known as the Mosquito was to make loitering kids disperse from storefronts without discouraging adults from shopping there.
Of course technology can work both ways, as was shown by the invention of phones that could ring without alerting adults like teachers and parents. Some entrepreneur to be took the sound that adults can't hear and made it a cell phone ring tone. Now as if it was not already bad enough that kids are able to talk so softly that adults cant eavesdrop on them, now they can receive calls right in front of them without them knowing.
Another study presented at this month's meeting of the Acoustical Society of America has revealed that non-Hispanic white people, in general, hear worse than other groups.
Secondly women, in general have been found to hear better than men. So this probably explains why a woman would call out, "I heard that!" when her man has just mumbled a disgruntled remark. Of course now women have their answer as to why a man who has been questioned why he didn't do something, he always seems to answer, "I never heard you ask me to do that."