"How Can You Tell That" joke

How can you tell that there's a drummer at your front door?
The knocking gets faster and faster.

How can you tell that there's a vocalist at your front door?
She forgot the key and doesn't know when to come in.

How can you tell that there's an accordionist at your front door?
He doesn't stop knocking even after you answer.

How do you know when a trombone player is at your front door?
The doorbell drags.

How do you know when there's a banjo player at your door?
His hat says "Domino's".