Cat repeller

This causes the device to emit high frequency noise which is uncomfortable to the cats, and inaudible to most humans (although they can still experience unpleasant subjective effects and, potentially, shifts in the hearing threshold[1]).

The devices are available in both battery and mains operated forms, the latter generally having a higher output, greater range and requiring less attention.

[3] The Royal Society for the Protection of Birds (RSPB), has endorsed a commercial product called "CatWATCH",[4] for which it receives 2% of the wholesale price of every device sold by the manufacturer.

Professor Timothy Leighton[7] from the Institute of Sound and Vibration Research,[8] has expressed concern about the recent growth in commercial products which exploit the discomforting effects of in-air ultrasound.

Typically they require a physical fence too high for a cat to jump over, with an electrified wire strung along the top.

In Japan, plastic bottles are often placed outside houses because of the belief that the light from the water will reflect and stop the cats from entering the property to urinate.