Aside from the fact that they don't deter cats, children and young adults can hear them, and lots of people get headaches from them. I don't understand why they are still allowed. I currently can't go more than half way down my front garden without setting off the one in the garden of the neighbour opposite. They aren't particularly friendly people and if it is pointed out to them will probably just shrug and say they can't hear it. Which they won't be able to as they are probably in their mid 70s. If I had more time I would consider dumping a load of junk in my garden just to annoy them. Also, of all the things to retain as I get older, I get to still hear sonic cat deterrents? Really?