Deoliveira, who is scheduled to offer classes in Toronto on Sept. 2 and 3, uses what many in the dog training community, including Andre Yeu, call "aversive conditioning" to stop a dog's unwanted behaviour.

Source: https://www.cbc.ca/news/canada/toronto/dog-trainer-dogdaddy-toronto-1.6952310?cmp=rss

Imagine other situations in which the dog that gets the aversive effect is, for example, a dog being walked by its owner, on leash, not barking, not ‘unfriendly.’

Source: https://www.fox26medford.com/buyer-beware-when-ads-mislead-about-products-and-services-for-dogs/

In a statement, they said: “Noise levels produced by such ultrasonic devices are likely to be aversive to some animals, potentially causing them discomfort, fear and/or pain and predicting an individual's response is difficult.”

Source: https://www.express.co.uk/news/uk/1822152/garden-home-foxes-cctv