Sevenhawke wrote:I should be more clear on the venue though.
It helps, yes. When you've said "haunted house", the natural assumption is that it would be indoors.
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Even with the concerns about indoors removed, you should still consider the decibel levels involved, even if it is a way from the path.
Personally, my recommendation would be to have it fairly
near, but a relatively low dB level.
The reasoning here is that while it will sound just as loud where its meant to, the sound levels will drop off better with distance.
For example, if the device is 120 dB @ 1m, and 10 metres from the path, it will sound to be 100 db at the path, but 80 dB 100 metres away (excluding sounds being absorbed, and just calculating the fall off with distance).
However, if 110 dB @ 1m, and 3 metres from the path, it will still sound to be about 100 db to the intended listener, but only 70 dB at 100 metres off.
I'm just using arbitrary figures there for the sake of a calculation, but it should get across the main point - if quieter, but closer, it will sound the same to the intended listener, but will be less likely to give itself away in advance (spoiling the surprise). Add in some extra fall off for the corn absorbing the sound, and you could have a pretty healthy ratio between what the intended listener and anyone else would hear.
On a similar note, what would be better than just a timer would be a system that was triggered only when someone was in the right place.
Be it by "laser tripwire" or whatever, this would mean it would be best posed to surprise the right person, as opposed to it just firing at potentially irrelevant times (and again, risking ruining the surprise).
You'd probably still want a timer involved to stop the tripwire setting it off too regularly, but it's all fairly simple electronics.
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Alternatively, although perhaps not in quite the right theme for this, what could be interesting is some trigger plate in the ground that loudly goes "clunk" when stepped on, then sets off a particularly loud noisemaker a few feet away (either as they step off it again, or after a second or two).
That would probably require things that were in the region of "too loud" though, even if it would be really effective.
After all, the trick to getting people scared is making them forget that it's fake - a good show with something like that would really break their scepticism.