Hi,
I found out this the hard way during a recent beach recording in Portugal. A
dummy head was used at around 6ft, and then lower to get it out of the wind,
except the waves caused some pressure difference and "swooshing" as they rolled
in. Higher up the effect wasn't as pronounced. - sand and with the mic low
down, plus a slight bank behind the mic were now causing what I understand to
be some reverberation from the direct (sea in front of the mic) vs reflections
from the ground and back behind the mic. and my body standing about 4 ft away
may of also caused some effect.
Side foliage, walls/building, structures under the mic rocks, sand, smooth
concrete etc. All of these have an effect on reverberation times, and moving
the mic down may cause changes in the direct to reverberant ratio - in effect
you are EQ'ing the mic to sound more pleasing to you. All depends on the mic
stereo recording angle involved and elevation. - Michael Williams has written
papers on this subject in the past.
BR,
Mike.
PS Rob, that's the author.
--- In Curt Olson <> wrote:
>
> Thanks Greg,
>
> I've experimented with ground effect quite a bit over the last year.
> To my ear, the "fuller sound" you mention seems to become quite
> noticeable at about 15" or so and increases rapidly to the point of
> serious ugliness at ground level. But in the 18" to 24" range, there
> seems to be a certain sweet clarity that seems to drop off ever so
> slightly as the mic moves upward to about head height -- at least
> that's what I've ovserved.
>
> I've never done any serious experiments with higher elevations like
> Walt and Dave have done. Hmmm... yup, that's definitely another
> element to look into.
>
> Curt Olson
>
> Greg Weddig wrote:
>
> > Curt,
> > I would generally agree with you, though I don't have any evidence
> > of such. Most of my ORTF recordings are done in that same range. I
> > think the ground effect most likely provides a bit of a fuller
> > sound, much like a PZM microphone would.
> >
> > Mostly I am trying to keep the mics out of the wind, and keeping
> > them low I find, depending on the geography, helps shield them from
> > nearby highway and city noise.
> >
> > --greg weddig
> > http://gregweddig.net
> > Paradise, CA
> >
> >
> > --- In Curt Olson <cro@> wrote:
> >
> >> Ever the respectful contrarian, I've recently discovered -- much to
> >> my surprise -- that the head-spaced barrier type mic rigs I'm
> >> currently using seem to render a slightly cleaner image when I have
> >> them in a "sweet spot" approximately 18" to 24" above the ground.
> >> This improvement is very subtle, and might be peculiar to my
> >> current rigs. I'm curious if anyone else has experienced the same
> >> thing.
> >>
> >> Curt Olson
>
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