Dan Dugan wrote:
> Note 1: Some amateur equipment is capable of being accurately
> calibrated; consumer MD recorders, for example, have repeatable
> stepped input gains. A calibration workshop could travel around the
> country and certify calibration of volunteers' systems (mike and
> recorder combinations).
I would not think that would fly very far. There is a established
procedure for certifying noise meters that are being used where legal
wrangling will be involved. About doubles the price of a meter to get
one of these, and all it really amounts to is legal documentation all
the way from some primary standard to the particular meter. But, without
it anything that gets into court will die. And I'm sure the park service
stuff will generate court cases.
Accuracy in the eye of the lawyer. Or pointless rules, all depends on
your point of view.
Might could be done on a recorder combo, at least as a technical thing,
but last time I checked there was a fair fee for it all. I decided I was
never going to get into legal wrangling with my meter, and don't expect
to publish any scientific papers on what I get (another bunch that want
that paper trail), so got a higher quality sound meter than I could have
afforded with the paper. Only difference is a sheet of paper and the
price, the meter without is exactly the same, and calibrated just as
well. If I ever needed to I could run the meter through the process and
pay the money.
Your 2nd line would be for the recordists to have calibrators, but those
cost a lot too. I'm not sure I'd trust consumer gear not to drift too
much. Using a calibrator at the beginning and end of the recording would
at least check that.
You can find all kinds of info on the internet about it all. I left most
all that behind when I quit being a consultant doing environmental
impact studies. Back then I used a rented meter. Now I could care less
what a lawyer thought, though I do calibrate my meter regularly. The
newer meters are much more stable than what I used to use.
Walt
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