Hi All

I will stick my oar in this one...

> 250-300 Hz is well within the frequency range that most humans can hear

Absolutely, hearing does vary between individuals, but the lower end of the
'heard' spectrum starts for most humans somewhere between 8 Hz and 30 Hz.

The upper end depends on age, as it declines from somewhere in the region 30
kHz - 50 kHz in young children. This deteriorates to 10 kHz - 30 kHz for
individuals at 65 years of age.

> Are cycles the same as Hertz?

Cycles per second = Hertz

> The "Fletcher Munson" study Allen provided says hearing starts at 500 to
> 1500 Hz

Balderdash, Most notes on musical instruments would never be heard if this
were true.

Human hearing varies between individuals, quite widely, but 250-300 Hz  will
be easily audible to anyone that is not actually deaf.

500 Hz is often used as a lower limit in communications circuits, because
the human ear can cope with minimal information, not because low frequencies
cannot be heard.

Best Regards & 73s... Dave Cushman, G8MZY
Beekeeping & Bee Breeding Website...
http://website.lineone.net/~dave.cushman