"Powell" wrote in message

"Arny Krueger" wrote

CNN had a piece on special ring tones only
teens can hear. Couldn't find link to said. Uses
very high frequencies most adults are unaware
of. Would allow teens to receive calls in the
school class room. I guess only other teens
would find it distracting in doing so.

http://static.orgday.org/orgday/Teen%20Buzz.mp3

I can hear it clearly on the Grados, but not on speakers
in the computer room.

As Robert pointed out, its mainly composed of energy
that peaks around 18 KHz. There are a bunch of spurious
responses all over the audio band that are about 110 dB
down. They are generally inaudible.
I did the same analysis as Robert using Blackman
spectral analysis in Sound Forge, but with much
different results. There is a bell curve starting a
14,961 Hz ending at 15,054 Hz with a max peak
at 15,014 @ -21.5 dB. Nothing else is indicated
whatsoever over the entire frequency range.

That sounds like what happens when you use a FFT with not enough points in
it. I used a 65,536 point FFT in Audition 2.0.

If you play this sort of thing through the *right*
crappy audio system, high frequency intermodulation
distortion (common in really cheap audio systems) will
move lots of energy down into the audible range.

I was under the impression that ring tones were
alternating frequencies but this appears to be just
a monolithic tone.

I see and hear evidence of modulation by about 1500 Hz, but that may be an
artifact of the MP3 reconstruction algorithm that Audition uses.

Audibly, its got quite a few audible artifacts when I listen with my HD580s.
Oh, and I can hear the fundamental.