Decent earplugs should still allow you to hear what's going on, I've worked in night clubs a lot and always wear ear plugs. Everyone that tries to talk to me just seems to stare blankly until I take them out but it's much much easier to actually hear them over the music with them in as they only filter out the rubbish background noise.
This is true.
Me and my mate bought some at the same time as this one specific club had stupidly over loud speakers and we noticed we woke up with ringing ears.
We could talk almost at normal level in the middle of the dancefloor. The ones I bought were about 8 quid.