6 ms·Ultrasound whistle? Sounds a bit cruel though, I dunno how it makes them feelby Biganon 8mo agoUltrasound whistle? Sounds a bit cruel though, I dunno how it makes them feelwingworks 8mo agoUsualy doesn't work. Needs a specific type of dog, and the right device. Most of the ones sold online are scams.sejje 8mo agoIt makes them bark more, in my experience.