In article ,
Don Klipstein wrote:
In article , zzznot wrote:
"Robert Green" wrote in message
...
It's amusing, in a sad sort of way, that it's so hard to find some simple
information. I downloaded the PDF but couldn't find any specs for the
sound frequency.

If it does voice, I'm going to assume it handles at least
the classic telephonic range of about 300hz to 3000hz, plus
or minus a couple of db.

High chance minimal upper portion of first formant range, as in above
400 or 600 Hz or so, and even then likely minus more than a couple dB at
frequencies that low unless it uses an actual dynamic loudspeaker
preferably at least 1.5 inches in diameter.

I have experience with an 800 Hz highpass 4th order Chebyshev filter
leaving voices fully recognizeable, and only moderately to
moderately-severely "tinny". Frequencies much below 700 Hz were
essentially absent here, roughly 10 dB down at 700 Hz and probably at
least 32 dB down at 400 Hz.

Most loudspeakers do not achieve flatness of frequency response to +/- 2
dB over their rated frequency ranges. One rated for +/- 3 dB has
traditionally been considered a "high fidelity" one, even if achieving
this only in a specific setup or the variable frequency signal being
moderately narrowband filtered noise rather than sine wave, and I have
seen very little improvement in loudspeaker fidelity in the past 25 years.

- Don Klipstein )

For those of us interested in such things (Fourier stuff, filters
(at least buying of them, etc)), PLEASE say MUCH more about your
setup, how you did it, where you got the parts, etc, etc.

Thanks!

David