Thank you for this, professor Rob! I find much to learn here.
Curt Olson
Rob Danielson wrote:
> I am not very good at it, but the most important factor in
> positioning a stereo mic array might be knowledge of the habitat
> and animal behaviors-- that is-- what places animals are likely to
> visit, likely paths they will take, spots they could pause and rest
> and the associated animal, plant and weather- related sounds that
> are most likely to occur. I go on the assumption that places that
> provide food, water, protection, transition zones between habitats
> and greater purview often present higher degrees of activity.
>
> For recordings that attempt to capture communicative or "ambient"
> space, the subject to mic distances can be quite large. Positioning
> the array where the sonic events and the local acoustics are not a
> cross-purposes is one way to imagine the task more comprehensively.
>
> I'm most fascinated by sound imagery that portrays as much space as
> possible while maintaining the unique nuances of the contained
> sounds. I agree with others that adjectives like, "full," "open,"
> "spacious," "clear," "transparent," and "immersive" hint at
> qualities behind this listening experience. Add to this the
> selection of passages when the combination of sound elements and
> patterns take o characteristics of language, music, narrative,
> (create expectation and engagement) -- the experience of the
> reproduction can become quite enveloping.
>
> Here are most of the acoustic factors I usually consider with steps
> I tend to follow:
>
> (1) I usually avoid setting-up near any sound source that creates
> long duration or sustained sounds including obvious /air traffic
> intrusions and natural subtleties like insects, water, leaves in
> wind, etc. I try to place sustained elements on opposing sides of th
> stereo field when their rhythmic natures are compatible and in the
> front and rear of the field when they are not.
>
> (2) I avoid exploring positions close to sound reflecting surfaces,
> including the ground at least initially. Close reflectors can be
> incorporated into the overall reverberation scheme but I find it
> easier to start studying reflections in the open. My portable stands
> extend to 7-8 feet but I sometimes set-up as high as 10 feet by
> tying-off to trees. Positions near ledges, of course, can increase
> the effective height on one side dramatically.
>
> (3) In order to get a sense of the local acoustics and ways to
> incorporate them, I stand in a mic location selected on the basis of
> biological clues and use hand claps or a clicker to determine where
> the primary sound reflectors relative to this point are located
> (e.g. the directions from which the claps echo back to me). I
> imagine the direction towards the loudest reflector as a potential
> center axis of my stereo array, then I try to judge whether
> reflections to the sides are balanced (whether similar or different
> in terms volume, mostly). If one side is louder, I move away from
> that side clapping about every 10 steps until the side reflections
> start to blend with more interesting character.
>
> (4) After I find a spot where the reflections from the sides blend
> together well, I experiment moving towards and away from the primary
> reflector noting changes in the overall character of the
> reverberation as the reflections mix. Sometimes small distances
> create profound changes, other times, the changes are slow and
> consistent. The reverberation formed when reflections decay together
> smoothly is often preferable to distinct reflections and
> significantly delayed echoes. Differing decay times can often be
> adjusted by changing the array position to feel more related in
> proportion. When the reverberation is very long and pronounced, I
> then consider orienting the array so the direction of the movement
> of the reverberation is aligned with its center line. I try to avoid
> positions between two parallel reflectors with chances of flutter
> echoes. When I find that the movement of the reverberation sounds
> best when it moves from one side of the stereo field to the other, I
> try to find ways to balance-out this inherent asymmetry. Reflections
> from above are often less localized but if they are localized, the
> can blend better if placed more towards the center axis.
>
> (5) I try to get to the site early so I can go through these
> preparations, set-up, start the gear recording and be gone hours
> before the expected "prime time." Rob D.
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