[markot86]

Not really looking for it for audio purposes, but where can you buy something that can read how much EMI is present in a particular area?

 

[JJ15k]

I don t really know, but I think a simple multimeter or oscilloscope should give you "something" since it s going to pick up the EM waves in the area.
However they are certainly not meant for that purpose, so the fact that EMI intensity is very low might mean that such methods would be innacurate.

 

[edstrelow]

You may want something like the "Elfix Volt Detector," made by Musset Industries. I bought this battery powered gadget some years ago, I don't remember where. It has an LED and a speaker. It lights and buzzes if the gadget is placed in close proximity to an electrical field.

Its original purpose was to see if the polarity was correct on plugs. If not correct, you could detect an electrical field at a greater distance from a component than when properly polarized. This actually does help the sound. Once I worked out polarization issues I didn't use it much, but it should be able to detect general electrical noise. I believe it can also be used to see if electrical sockets are live.

I did a quck google and seemed to keep finding European sites.

http://www.russandrews.com/product.asp?pf_id=1870