I chased a sound once that seemed to be coming from everywhere. It would happen every few minutes, and it sounded to me like a small servo motor actuating. Looked through the entire house, from the attic to the basement, and I could hear it in every room but not pinpoint a direction or location. It was driving me crazy.
My wife figured it out. It was a cow mooing in a game our toddler daughter had been playing on my cell phone before I stuck it in my pocket.
