I've never done this myself but I believe you can spray carb cleaner(?) around the vaccum lines, basically just around the engine, and if the revs jump at all you've got a leak.

This may be more common on some makes than on others but in some cases a plugged/broken pcv valve can result in the engine's seals being blown out, since the crankcase pressure can't escape. Sometimes that happens, others it just causes oil consumption (past piston rings) and/or the pressure gets by the dipstick.
When replacing it, I found it helps to use a vice grip to pinch the clamps while you remove/refit the hose. This is especially true on my car since the pcv valve is located under the the fuel injectors(maybe same on yours), more likely to give you scraped knuckles than on most cars.

I sort of have an open intake on my civic, stock filter box and so on to the engine but none of the tubing that draws air to the filter or the resonator 'box' that comes on the car from the factory. It doesn't cause any sort of whine, sounds 99% normal unless you give it more than 1/2 throttle.

Anyway, I think VortechIntegra may be onto something with alternator whine. I don't really know anything about that though so I'll have to look into it.