Among the ways people try to get rid of mice and rats is to use something called an ultrasonic rodent repeller. This is designed to emit sound waves that people can't hear, but that rodents can. But does it really work as a rodent repellent? Well, maybe sometimes, with certain types of pests. But overall, not very well, most of the time. That's very ambiguous, but so are the claims made by the companies that manufacture these ultrasonic devices. In order to make a product claim, there has to be scientific evidence backing the claim. Providing that isn't easy for a device that doesn't always work. Here's what to consider.