That's the point. Instead of the air being recirculating back through the intake(no sound) it comes straight out the pipe into the atmosphere.
Other blow off valve adapters accomplish this same thing by stacking up the valve. To my understanding, this accomplishes the same exact thing. The valve stays closed all the time unless you're in boost and let off the gas pedal. Even though you see that 1" port wide open on the blow off valve side, the valve is closed within.