When people knock on your door do they go: knock-knock or knock-knock....knock-knock or knock-knock-knock.. or how?

In the very posh Avenue  where I live in London......ours is the only house that has Knockers .....All the other home have securi'tities cameras and electronic entry systems......

Knockers do look better and have been a'round for ever it feels.... :)D

I don't hear people knock on my door where I am in my house. And had people to say I did not answer and never even thought of ringing the door bell. I guess they do not know what that button is for. 

I go, knock....knock knock knock knock.....knock....knock.

I varies by who is knocking. But most everyone knows not to come to my house without a call ahead. Letter carriers, UPS  etc are allowed.