Multiple wireless devices using same frequency?

I am looking at buying a pair of wireless headphones (The Turtle Beach PX5's, specifically. - http://www.turtlebeach.com/products/ps3-gaming-hea... ) and in my research have read several reviews online. One thing that keeps popping us as a 'con' is the fact that they operate on 2.4GHz and they say this can be problematic if you have other things, such as a wireless router, using the same frequency. However, what the reviews don't state is HOW this can be problematic. I checked my wireless router and it uses 2.4GHz frequency.

I've googled around but haven't really found any proper answers so my question is this: HOW is this problematic? Will their be sound interference with my headphones? Will the range be reduced? What happens? My apartment isn't huge so I would only be sitting perhaps 3 metres from the transmitter while using the headphones. Should I still consider these headphones or look elsewhere?

I will cross post this as I'm not too sure what section would best suit this question...

Thanks.