A beep cuts through the hallway, then disappears before you reach the room. ChirpHound is built for that particular kind of domestic nonsense. The live US App Store listing identifies it as a Utilities app by Robert Corbin, with version 4.1 priced at $2.99.
Start with Auto Discover or choose a frequency preset, then walk through the space. ChirpHound learns the local noise floor, isolates repeatable tonal energy, and gives you warmer-or-colder evidence as you move. If the device chirps only once a minute, wait for two chirps and use the Next Chirp Clock: WALK, FREEZE, NOW. The countdown gives you a better chance of measuring the next sound instead of talking over it.
When you have two likely rooms, arm one and let the next detected chirp become its evidence. Re-measurement replaces stale evidence, and the app ranks rooms by detected peak with a confidence margin. The listing also documents Signal Lab, a Hidden Source Checklist, and a Chirp Field Guide, all available without an account. The publisher privacy page says audio is analyzed on the device and not recorded or uploaded.
You can now stop circling the house and test the next room with a trail of evidence.