A number of reviews for this mention a whining/buzzing noise coming from

I've attempted to just ignore the noise or see if I would get use to it; I could not

Also others have noted a humming noise from the usb ports

The usb power adaptor makes a constant humming noise when I have something charging in it (which is every night to charge my phone.

I expected a greater noise reduction.

The noise was much quieter initially

The noise is louder than our frig

Started making a humming noise less then 12 hours of being plugged in.

Works great!Edited to add: I'm changing my review to only two stars, because the strip has started making a loud hissing noise if I leave a USB cord plugged in with nothing charging, or if you have only one USB port occupied out of one of the pairs

I'm not sure what would be causing a power strip to make a loud hissing noise, but it is

Edited yet again to add: about a year later, this unit is making the same loud noise as the last one, except it doesn't seem to be dependent on the USB chargers

I actually have one in my bedroom and the slight noise I described makes for nice white noise for sleeping.

Constant humming noise is disconcerting from this china made outlet.