Ask HN: Where is that noise coming from?

put the two smartphones in the freezer.

put the other person and the cat in the rear bedroom and lock the door.

cotton balls.

if you don't have them, you can cut up your socks.

you put them in your ears.

if the sound keeps on, then the source of the sounds is just that you're crazy and delusional.

if not, it's just the furnace

it doesn't matter which, because the other human will have called emergency services and you'll be going to a nice place

Install a recording app on the phones, put one in a soundproofed location and turn both on and do a differential between what they record. Once you are satisfied on playback there is a signal, start doing triangulation.

Ask the other person if they just farted...if not then it's the cat