In most cases, a noisy filter is caused by air lock-ins. These are air bubbles in the rotor housing, causing vibration and scraping of the rotor / impeller against plastic.
Prolonged running of a filter like that can cause damage to the rotor / impeller.
How to remove the air:
1.) Unplug filter (never run a filter without water - this will damage the unit!)
2.) Take filter out and shake it a few times
3.) Submerge the filter again and give it a few shakes underwater
4.) Plug filter back in
5.) Give it a few shakes and knocks to knock out any trapped air
This usually solves a majority of noise complaints with internal filters. Should the unit still be loud, have a closer look at the suction or installation mechanism and make sure the filter housing is not touching any glass or decoration. Vibrations (noise) will be transmitted and increased that way.