An electronic mouse repellent can work a couple of different ways.

One way the electronic mouse repellent can work is through the use of ultrasonic sound waves to drive away mice. These types of high frequency sound waves irritate the mice and are eventually too much, forcing them from your home. These sound waves vary from 30 to 60 kHz. And to help to make things even worse, these sound waves are emitted but not repeatedly at the same frequency. It will keep switching frequencies causing more discomfort and the mouse can never adjust to it.