Effects of the doorbell!!

I seriously think this is a funny happening, the other afternoon my son was home sick and laying in his bed with the door closed, I was in our room and the dog was on our bed sound to sleep... and all of a sudden THE DOOR BELL RANG! I look out the window and see the UPS man leaving me a delivery and I knew that was his way of letting us know we had a delivery, Cameron comes hauling out of his bedroom, the dog wakes up and runs to the door and I letting them know what the deal is, I was laughing so hard later on about this because whenever the door bell rings everyone in the house kinda freezes and is wondering who is on the other side of the door, I have talked to other people about this and they say the same thing, that sound is a combination of excitement/curiosity, what a simple excitement!!!