I wanted to get a noise meter for a long time now, but they’re expensive. A lot of daily things just sound… potentially dangerously loud. Public transit, for example.
I want something that can go a least up to 20kHz, most do just up to 8kHz. There’s one supermarket I was at once that had some “repeller” which felt painfully loud. It kept changing frequencies, lowest at 15.5kHz when I checked with my phone. I was considering throwing a rock/brick at it while waiting there, but hiding behind a corner seems fine enough with higher frequencies.

Probably the same thing but with different branding.