Radarcan DOG BARKING SILENCER PRO User Manual page 10

Remember, when installing the DOG BARKING SILENCER
PRO, that ultrasound waves do not penetrate walls (brick,
plaster, etc.), or wooden room dividers, glass, plasterboard
false ceilings or other solid materials. Place the DOG
BARKING SILENCER PRO within the space to be protected,
and avoid blocking the flow of the ultrasound waves from
the front part of the device.
The graph shows
how ultrasound
waves bounce
back and spread,
so that the dog
hears them and
stops barking.