At 9:28 AM +0000 4/6/09, Greg Simmons wrote:
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>Rob Danielson <> wrote:
>
>> If I'm following umashankar correctly, the only way one could
>> practice the theory of "flat frequencies response" --that is-- not
>> correcting for volume and monitoring Hz balances difference-- would
>> be to match the sound playback level of the original sounds.
>
>According to his website, Gordon Hempton uses such a process when
>preparing his binaural 'sound portraits'. He measures the SPL at the
>mic position during recording, and matches it at the monitoring
>position in his studio when preparing the recordings for release.
>The idea has always made a lot of sense to me, but I'm too lazy to
>carry an SPL meter...
>
>The SPL Meter widget for iPhones might make it easier, however.
Hi Greg--
A relevant correlation.
I believe the playback level calibration process he used on his first
CD's was a little different. There's a soft tone at the very start of
the CD that was on par or slightly softer than the background sound
level as the background ambience in all of the recordings on the CD.
The instructions were to adjust the play back volume until the
reference tone was barely masked by the room tone which would vary
with environment.
Ingenious as it is, the approach has trade-offs in my opinion. One
one hand, the self-noise of the mics isn't audible and effects
(calls, water etc) seem to rise-up out of the very place you are in.
The drawback is its not really possible to hear subtleties of the
ambience one would be aware of while listening in the actual space.
And, of course, the birds are not in the room! Gordon is very
interested in the acoustics so its instructive that he might have
changed his calibration process. Its also possible, given where he
lives, that the background sound level in Gordon's living room is
lower than most. :-)
Amplification is the most powerful variable at the audio engineer's
disposal. Maybe this is part of why we are so passionate about
getting the playback volume of our recordings "right." One time I did
an 8 channel sound installation in a planetarium that was in a
separate building. I arranged to have the HVAC system and all of the
gear that made noises turned off right before the show began. With
this very low background level in effect, I could use Gordon's
suggestion and play back the natural space night tracks at a very low
level. The illusion wasn't perfect, but the impact was quite
life-like. In contrast, city street ambience at less than typical
SPL's felt terrifying. Rob D.
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