Ultrasonic sound is audible!?

Topo Stop generates randomly microprocessed sound emissions (1-2 second long signals at approx. 1-40 sec. intervals) which effectively stops the pest from growing accustomed to the sound,

During the sound emission the micro processor in Topo Stop also creates frequency jumps at random with a duration of less than a micro second. These jumps are just about audible to humans since the speaker of the device physically can´t move that quickly, thus a faint click can be heard. In the same way the speaker won´t quite cope with the very quick changes in frequency the hearing of the pest won´t adapt either, hence mice and other rodent pest will feel great pain in their ears.