I've NC for this.
For the past few weeks I've been hearing a really high-pitched sound while in my garden. It's very shrill and has made sitting outside in the sun really uncomfortable because it's like a needling feeling in my ears. It's coming from various parts of my NDN's garden, sometimes multiple bleeping at once.
I did some googling and realised the sound could be ultrasonic cat detectors, although my research suggests they're meant to be inaudible to humans. I popped next door to ask them and see if they did indeed have these deterrents in place.
While I waited for NDN to answer the door I spotted five in their front garden (probably approx 5x10m space including the drive and gateway). Mrs NDN answered and said that her DH had fitted them so cats don't shit on their lawn (fair enough). Apparently there are more round the back.
I explained we can hear them very loudly from our house and that it's making enjoying our garden very difficult. She said she'd ask Mr NDN to have a look at them. I politely suggested this might be a good idea as they're (I think) not meant to be audible to human ears, only animals. Although we live in a reasonably built up area no-one else's garden is adjacent to theirs.
They seem to go off more in the sunshine (barely any noise when it rains) and sure enough they're going at regular intervals today now it's brightened up. WIBU to go back round and ask what's happening with them? I feel like I'm getting a headache from the noise (not usually a headachy type) - we can clearly hear them in the house with windows open. I really don't want to be 'that' neighbour and we usually get along well in distant way.