Vacuum one way valve
 

I have a hose coming out of the back of my intake splitting off into a Y splitter and on one of the sides has a one way valve that says "engine" > and it will suck air in but not allow air to come out of it.

My question/concern is that it is not going anywhere it looks like it should be hooked up to a line but it is just sucking air from under the hood. And I can hear it while the car is on....