On the drivers side of my 02 Disco....there is a vent between the door and the dash. When I am driving I can hear air running through this vent, very annoying. What is this vent for? Would anything happen if I cover it to try and stop the air noise?
[hr]Just tried to cover the vent...went for a drive...still has same noise. If I crack my window or open the door, the noise goes away. It is actually quiter with a cracked window than with it all the way up. I guess with the pressure change the "air" noise goes away.

So, the noise is not coming through the vent that I thought it was, it is coming from somewhere else...not sure where though

 

Is it a vent like the vent for a cooling fan on a laptop?
It is a cooling vent for the fuse panel, take a vacum and clean the vent, suck all the dirt and dust out of there, there is a little cooling fan, like on a laptop.
It could be clogged or the fan could be going south.

 

I am not sure exactly where the noise is coming from. I thought it was the vent. It only makes noise once I get up about 40+ MPH....low speed = no noise. When I crack the window, just a little, it sounds normal. I am not sure, guess I will keep trying to troubleshoot.

 

That sounds like a better description. Sounds like your door needs to be adjusted. Or the window frame needs adjustment.
With the door closed look around the outside of the window frame and look for big gaps.

 

OK, I found a fix for my noise. Spike you are probably right...the door needs to be adjusted. For the poor boy fix. I bought some foam tape at Lowe's and placed it around where my door closes next to the rubber seal. Air noise is now gone. Cheap fix that should work long term....cost $3

 

You could have simply open the door, loosen the door catch or striker, tap it in a little bit , re-tighten and it would have been fixed. You could also loosen the window frame, have someone pull it inward and while its being pulled, re-tighten the window frame bolts.