gentlemanly

The way to do this is to knock three times and then knock for a few seconds.

Knock at the door

The loudness is moderate, too light, others can not hear, too loud, others will feel sick.

When you knock at the door, you can't punch or kick with your feet. Don't bang on it. If the elderly are in the room, they will frighten them.

ring a doorbell

Also be polite, press slowly, and press again after a while.

Don't be so hasty. "Ding Ding Dang" is not enough to make the doorbell broken.