I’m going with you can’t. Most microphones and certainly all home microphones can’t record ultrasonic sound. It’s Marketing. Nobody is going to pay money for a home microphone that can pick up interference to their voice or piano from motors and video screens.
I don’t think you have the whole story. Any generator that can produce ultrasonic effects in your rooms would be loud enough to kill people on the other side of the wall. Ultrasonic doesn’t go through barriers very well.
There you have two problems.
- You have to get someone to pay attention to you and not run the other way. There have been a number of similar forum postings.
- There’s no way to certify a recording or produce time stamps, so Audacity can’t be used for Surveillance, Law Enforcement, or Conflict Resolution.
Koz