Could you please take the device out of the vent, place it on a desk, turn it on (on default RPM), and see if the noise differs from what you can hear in the duct?
Also, please send us a video of the device working on the desk so we can see if something is wrong with it.
Please check the vent and make sure nothing is interfering with the fan blades and if there is any vibration.
Looking forward to the video.