This small device has been effective in masking outside sounds ...
This small device has been effective in masking outside sounds (specifically early morning loud chirping birds) so I can sleep restfully.  I wish I had thought of purchasing this item years ago.  I would give it five stars if there was greater differentiation of the swooshing sound when rotating the top.  Thank you Dohm, it has made a world of difference this Spring.
Rating: 4 stars