Raimund, you wrote,
> Note that the animals don't care about A-weighting at all (which is adopted
> to the human auditory system). So, I would recommend to deal entirely with
> unweighted noise levels in this application.
Indeed, it has little to do with how animals hear. I'm sure each species has
its own Fletcher-Munson curves.
To repeat for our less technical colleagues, A-weighting is a filter that
basically discards the bass. it's intended to give a realistic assessment of
the perceptibility of low-level noises. Low-level noise is usually dominated by
inaudible rumble, and unless the rumble is filtered out, sound level meters
will read it way too high for purposes of comparison.
Unfortunately, since sound level meters all have the A-weighting option, and
non-technical users are notoriously unreliable in noticing how switches are
set, most environmental sound levels are measured, for forensic purposes, on
the A-scale no matter how loud they are. Noise annoyance laws and national park
SPL limits for different zones specify dBA. This is terribly wrong for
assessing annoyance from music, for example, or from jet overflights, but we're
stuck with the standard practice.
As I do a lot of recording in national parks, and I want my recordings to be
useful for soundscape management policy formation, I want to calibrate my rigs
so that I can report the SPL in dBA when desired.
-Dan
p.s. Reporting SPLs measured by directional mics opens another can of worms.
-dD-
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