Conversation

I'm surprised to discover exactly zero ultrasonic SPL meters on eBay. Usually, when looking for rare stuff like this, you'd at least come across some expensive second hand equipment.

I'm looking for one because I'm interested in building ultrasonic devices that can repel cats, and if I'm going to be generating uncomfortably loud noises, I'll need to make sure that I'm staying within safe limits. If this was a smoke alarm, my ears would let me know, but they won't help with ultrasound.