The chambers are actually resonators. When an intake valve closes rapidly the air flowing toward the engine in the intake tube is actually forced backward away from the engine and without these resonators you audibly hear a boom type sound with every valve cycle. These chambers give the air a place to go for a split second until the valve opens again thus reducing that sound. You typically wouldn't hear it at higher rpms but certainly do at lower ones like idle. They also help the air flow in be smoother since the air blowing back can hide in these chambers instead of just colliding with the air that is on the way in. This helps power , fuel economy, smoothness of engine running, ect.