DIAGNOSIS That's usually the sound of refrigerant moving through the coils, which is normal during startup and operation, but if it's constant and loud, the unit might be tilted.
FIX Check that the dehumidifier is sitting perfectly level on all four feet on a solid floor. If your floor is uneven, you can put a thin shim under a foot. Also, make sure the water tank is pushed in all the way and seated correctly. A tank that's not fully seated can amplify internal sounds.
IF THAT DIDN'T WORK The noise could be from water collected in the base pan under the bucket. Unplug the unit, pull out the tank, and tip the entire dehumidifier gently to one side over a drain or towel to see if any standing water pours out. Let it dry before plugging back in.
HEADS UP A loud knocking or grinding noise is NOT normal gurgling. If you hear that, shut it off immediately—it could be a failing compressor or fan motor.