Tonight, thanks to NPR, i got some more information about the supposed anti-adult ringtone.
For those unfamiliar with this story, In Britain an enterprising gentleman has determined that the best way to deter local yoots from hanging around the front of the drugstore is by playing a very high pitched tone at them. The theory being, those yoots who’s hearing has not yet been destroyed by their iPods or curb thumping bass beats would find the tone so annoying they’d leave. It is, by most reports, a success.
Some even more enterprising young yoots, have determined that this magical tone is useful for their own evil purposes because reportedly most adults over the age of 30 are not able to hear it.
Mind you, i can hear a CRT refresh scan rate. In fact, my hearing tops out at around 16,125Hz (give or take a dozen or so Hz). i was the one that told my parents the electronic mosquito repeller batteries were dead. So, naturally, i was very interested in hearing this inaudible tone.
So i clicked on the link, and heard nothing. Odd.
So i turned up the volume. Still nothing. i tried playing a different noise just to see if my speakers were working and once my ears stopped ringing, i tried it again (Note to past self: Turn down sound BEFORE playing test sound.) Then i turned on the “Bars” Visualizer. That’s the el-cheapo oscilliscope on your computer that tells you what frequencies are being played. Still nothing.
See, even very high pitched sound has to show up on those. You should see something like this:
My bet? Since most audio compressors (like RealAudio, WMV, and MP3) toss out very high and very low frequencies in order to save bandwidth, the baby got tossed out with the bathwater. As an added benefit, since the tone is reported to be inaudible to anyone over the age of 30, the person doing the proof probably didn’t hear the tone before they encoded it either.
Oh, and by the way? Most cellphone speakers aren’t capable of playing that high a frequency either, so the tone usually gets cranked down to the 16K range. Bingo, you’re in my territory. i’ll also add that a number of computer speakers also can’t manage that range
And just in case you all want to find out how good your hearing is (or just want to drive the neighbor’s dog nuts), here’s a 2 second burst of 20KHz, the maximum human audible tone. Anne Marie hears it just fine.