Cem Uzunoglu:
I believe what you say, I just don't believe that what you're hearing is 10
kHz, unless, by "hearing", you mean "feeling a weird, rather unpleasant
noise".
Most healthy adults can hear upto at least 12kHz pure sinewave. Some
younger children can hear nearly 20kHz. As a youngster I recall hearing
an annoying whistle from the line flyback transformer on some TVs
(presumably the ones with something loose). That is around 15k6Hz. I can
still just about hear pipestrelle bats calls - though presumably only
sidebands off their chirp since the fundamental is ~45kHz.
I had the opportunity to to test a moderate sized audience with a pure
sine wave pulsed and the kiddies hands started going up at 18kHz last
year. I could hear it at 14kHz and most adults were around 10-12kHz. A
few elderly folk still couldn't hear 5kHz but by then it was getting
annoyingly loud for the rest.
In my first job I drew the PCB for a graphic terminal, but my most
appreciated ability was to spot immediately if the newly programmed synch
generator was working within the CRT's specs.
Let's say 4186 Hz.
C8 is just the pianos highest note. Nothing special about that and most
people can easily hear it. It won't sound much like a piano note though
unless you include at least the third harmonic. There is something
seriously wrong with your hearing if you cannot hear 4kHz.
I set my Theremin up to do 50Hz-10kHz which covers the range most useful
for its ethereal style weird music. Linearising hand movement for
logarithmic frequency control was a nightmare. The Dr Who theme is
harder to play than it sounds as is Good Vibrations.
People may not hear higher frequencies distinctly, but that doesn't
prevent other parts of the ear detecting the sharper rise time. You can
squeeze intelligible speach over a very limited bandwidth, but it
actually takes skill to get broadcast quality high fidelity audio right.
UK DAB radio has failed in this respect at least for classical music.
Regards,
Martin Brown
