Seriously, the odd note. I’m sitting here yesterday morning working on photos and there was a peculiar wispy beep sound from the kitchen. We should have no beep sounds coming from the kitchen, but there it was.
And then tonight I wake up and come in and sit down and after about five minutes from behind me there was a brief and clear pipe kind of whistle in G. It was so clear and resonant that I was able to check out on the piano what the note was, which is how I know it was G. If it was coming from he radiator, it seems it would sound like it was coming from the radiator. Instead it just sounded like it was coming out of the empty air.
We live in a flatulent old place.