They're not the only manufacturer making something with ultrasonic sounds. I'm sure you can use a mouser device or the like to test the concept (sound should travel through a waterproof bag)

The manufacturer claims that using ultrasonic waves, it cleans laundry and other things effectively but also gently enough to be used for delicate items. They also claim that it could be used to clean items that can't really be cleaned any other way. Is there any way to verify this?