Disaster
IF you can actually get the units to produce any sound (a big if, given that the app crashes every day, and there are no manual controls), you'll find it's just another white noise hissing sound, except in stereo.  The tiny speakers are so cheap that you cannot even make the the tone deeper.  These would be a rip off for $50; I have no idea how they are trying to charge $300 for them.
Rating: 1 stars