You decided to keep knocking.
Knock.
Knock.
Knock.
Knock.
After quite some time your arm gets tired and you stop. While it looks like someone might be up-keeping the yard it's clear no one is home. You are losing hope of what to even do.
You decide to give it one last tap on the door before calling it a night.
Knock.
As you turn your back you hear a faint series of sounds that have some short and long tones to them.
THUD || TAP THUD TAP || TAP THUD || TAP THUD THUD TAP