"Powell" wrote in message
news

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.

I ran a Sound Forge spectrum analysis. The prominent peak is -9dB at 18019
Hz, but there is some power, at extremely low levels, throughout the audible
spectrum. Total average power is close to 0 dB. The part that most adults
are likely to hear are greater than 120 dB down. By turning the volume, we
hear lower frequency components. I cannot tell if what I'm hearing is the
18019 Hz peak, or the lower frequency components, or DAC alias beats.