At 11:08 AM -0700 8/29/05, Dan Dugan wrote:
>Rob Danielson, you wrote:
>
<snip>
>
>The hope is to increase the scientific value, and the defensibility,
>of amateur contributions to the parks soundscape inventory and
>monitoring efforts.
admirable.
<snip>
>
>>For
>>record level instruction, how about something like "...set at -5dB
>>during a loud, distant event. If a louder event comes, re-adjust the
>>record level for -5dB (or -10dB, but this is often not marked) and
>>record for another 30 minutes"
>
>Too vague and too variable. Of course the voice method is quite
>variable, but it can give the recordist a place to start from sans
>any other calibration method.
Oh I see, my suggestions were based on capturing ambient levels, not
for recording loud effects at the front gates, near roads etc. That
they write down the level and don't change it is most critical.
I've had college students use the voice level method. I wouldn't
argue for its value for SPL calibration
>
>>Bit depth helps with the accuracy of
>>the analysis tools I've used and some extra noise is not usually a
>>concern. I've used the voice method you describe many times in the
>>city, isn't the dynamic range in the woods too low for this method?
>>(or is the pollution THAT serious!)
>
>Recording with 65dB SPL peaking at -5dBFS (and averaging around
>-15dBFS) brings the mic noise well above the floor of 16-bit
>recording. For the last several years I've recorded a wide variety of
>soundscapes with this level, which is what I get with 183s into a
>Sharp MD at MIC L 17. I found I had to drop my level 6dB (MIC L 14)
>to cover the crowded parts of the park. I can't recall any natural
>sounds except thunder I've had to turn down for, and some wind
>situations where the sound per se wasn't that loud but I wanted to
>keep the wind noise in the mics below clipping.
For relative ambient levels above the noise floor this should work
okay. Again, I was thinking you were going to study the
ambience/influences at a distance You may go down to just few bits
resolution if its a really quiet setting. Maybe these quiet settings
are no longer there to study.
<snip>
>
>The session length was developed after experience with attended
>logging. It's about as long as a volunteer can sit still. I've done
>forty-minute hand-held takes, but I'm a fanatic!
If I specify 15 mins, I get 6-8 mins of non-jostled, fixed level, recording=
.
In similar exercises I've given, it takes about 30 minutes to take in
the setting's distinguishing features and make coherent notes. My
thought is: may as well record while writing. Standing silently with
a body mount is very demanding for any length of time. Rob D.
>
>-Dan Dugan
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