Works Great, Perfect for Travel
We bought the Marpac Sleepmate 580A to replace the fan we'd been using for years.  We both work second shift and white noise makes it possible for us to sleep through the morning neighborhood noise.  This is an excellent replacement for our fan.  The sound is louder, more uniform and can be adjusted to suit our preference.  It doesn't block out external sounds, but I don't think we  could sleep with something loud enough to do that.  It instead smooths out the background sound so you're not startled awake by sudden loud noises.  We travel frequently and brought the machine with us on our last trip.  We were very thankful to have it.
Rating: 5 stars