It might work!

My friend had mice coming up onto their bed at night and freaking them out so I put this app on my old 3G phone, turned on the sound for mice, locked the screen and told them to set it under their bed. Last night they didnt even hear the mice come near the room when previous nights they could hear them crawling all through the walls and around the room. We will continue to try this at night and I will update my review if it ends up not continuing to work.
I really like the feature of playing multiple sounds, that is very thoughtful.

Nathanjudah about Ultrasonic Pest Control