In its pure sense, Compression makes everything an equal volume, like television shows, but the sacrifice is dynamic range. The extreme example is Nickleback CD's which, if you look at a wave file of one of their tracks, it looks like a 2x4.
That said, try some presets on your wave editor. I use Goldwave, and it has about 5-6 presets, some very light compression and others quite heavy, so I would take a 15 second sample and try some out. Goldwave also has the ability to make your own presets by increasing the aggressiveness of the effect and saving it.
I've never found Compression to be that effective in eliminating crowd noise. I think a directional mike or higher mike placement is the better solution. Low placed Omnis in a loud crowded rambunctious rock concert would be disaster.