Sound Changes

In regards to the "fat" hose coming off of the blow off valve, i had it just hanging down in the engine bay since i installed my cold air intake. I bought a mini air filter "about the size of a golf ball" from the auto parts store. The sound between gears with the hose open is a "pop-hiss" sound. When I put the mini air filter thing on the end it makes a "fluttering" sound. Why is this and what does that hose do to make this sound?
Thanks! Joe