In my experience:
My Wind Harp was purchased from a Musicmaker's Catalog in 1987 and bears
a STRIKING resemblance to a Paraguayan harp! All right, it IS a
Paraguayan harp. I frequently play it outside, and if the wind blows, I
turn it into the wind, in a direction that would produce "luffing" if it
were a sail, and it produces the most gorgeous sound! Makes me wish I
could play that well. ;)
In my humble-and-easily-challenged opinion, anything with a good
soundbox and loosely strung strings, turned the correct direction into
the wind, would produce an aeolian harp effect. My harp has nylon
strings - obviously a better choice than gut or brass for weathering.
It's finished with Tru-oil, a penetrating oil (much like the Dutch
penetrating oils) that is normally used on gun-stocks. This finish
doesn't seem to interfere with sound, is easily spot-touched-up if it
wears in any location - ie, unlike varnish, you don't have to strip the
entire finish to re-finish an area. Penetrating oils are also very
protective to the wood, and very durable. Again, an advantage in
gardens.
The sound I get, with 26 strings and a decent sized soundbox, is audible
to at least ten feet on a quiet day with a light breeze. It is more
audible in the lower and mid register than the upper - this could be due
to tension, or to string length, or to soundbox depth, or one of those
elf-design functions I'm entirely unaware of.
A few experimental thoughts:
If I were to make an aelian harp, which I might since I love the sound
so much (I've been known to stop in the middle of a recital to hear it)
I'd go for a wheel shape, with different (but harmonizing) notes for
different wind directions. I'd also double or triple string each note
for amplification. I assume, to get the wheel shape, you'd have to
arrange it kind of like a spiral staircase over the soundbox, which
could put some of the upper strings quite a ways from the soundbox if
you had very many, especially if you use multiple strings. Could be
quite decorative, though, if you alternated notes going up so that the
multipe strings per note were separated by other notes going a different
direction.
For weather-proofing vs. sound, does anyone know what a lute-type back
with a fiber-skin drumhead material stretched over a wooden frame would
do to the amplification qualities of the instrument? I assume the
aritifical drumhead would wear better than organic materials.
Naturally, you'd need a drainage hole at the bottom if you were going to
put it out in the open, and if you had a sound-hole at the top, which I
assume you would.
Thanks for giving me some materials to daydream over! :)
-Laura