Ever heard a noise that you think is something VERY LOUD and very far away, only to discover it was actually something really quiet and possibly in the same room.
The 2 sounds could be created by something very different, for example :
I just thought I heard a ships fog horn in the distance, for a moment I really did think it was a fog horn....
.... until I realised it was the spring in the door handle on the kitchen door releasing itself after getting caught on something..
Strange but true !
What wrong noises have you heard recently ?