Ultrasound is a spectrum of sound which starts just above human hearing range. Rats/bats/dolphins have the ability to detect ultrasound with varying frequency ranges. Rats use ultrasound for communication (distress signalling/mating calls) and to a certain extent echo location. Carcat bombards ultrasound waves with unique patterns which disturb and disorient the rat.
In human equivalent terms, it would perhaps sound like a very loud unbearable continuous screeching siren. The advanced micro-controlled automatic frequency technology ensures the rat does not get accustomed or immune to the wave pattern. Rats are highly territorial creatures and for existing infestation, there may be initial resistance for a few days but eventually the rats will be driven away.
The electronic rodent repellent creates an intense auditory stress for all kind of rodents and repels them permanently with high frequency sound waves.