Yeah, this one's common. Turbo is the highest of the three air cleaning levels and is designed to move a lot of air quickly, so it will be noticeably louder than the lower settings.
First, make sure nothing is blocking the air intake grill or the output vents. A piece of paper or a curtain sucked against it can cause a racket. Slide the speed selector bar back to LOW or the medium setting for normal, quieter operation. Turbo is meant for short bursts when you need maximum air cleaning power.
If that didn't work, and the noise is a grinding or rattling sound, the filter might not be seated correctly. Turn the unit off and unplug it. Open the grill cover and check that the True HEPA filter is properly installed and that the pre-filter is clean and intact. A warped or damaged filter can cause vibration.
Heads up: The unit is recommended for extra-large rooms (465 square feet). If you're using it in a much smaller room, even the lower settings might seem loud because it's moving so much air relative to the space.