It's remarkably good at interfuzzing some mid-level noise, not all. Better at barking dogs than I would have thought, also moderate TV & American "music" noise.<br /><br />Don't notice a big difference in the settings on the machine (it has two, with a dialing mechanism that changes the frequency). The directions suggest putting the device above rather than below you, and I found this suggestion useful.
Rating:
[4 of 5 Stars!]