I seem to have two types of air vents for the hvac on the second floor of my house. Attached are pictures of the two types. One vent has a round metal air flow control inside which apparently can be turned to control air flow. The second vent seems to have a plastic baffle which doesn't seem to be adjustable. This vent seems to make more noise when air is flowing and I'd like to reduce the noise. I don't know what this second type of vent is, or whether it should be replaced with the other type. Can anyone help me identify what this is? Thanks.