Yeah I was wondering the same thing. At first I thought it didn't really matter, you'd just go by the length of time between knocks. But then I saw the "be quiet", which would be indistinguishable from "cone here"...

Maybe a knuckle drag?

I'm not certain but I'm assuming a short knock they remove their hand quickly after impact and a long hand they keep their hand pressed against the wall after impact. Or maybe the difference between knuckles and palm knocks?

If you do a long knock, you can kinda hear the delayed release from the wall if you listen closely.

like the engine of my car at idle

It's like Morse Code. It really isn't about the length of the sound, it's the spaces between them. A dot would have a short space after it, a dash would have a long space. So dot dot dot would be three quick knocks, dash dash dash would be three slow knocks.

Yeah like maybe the one prior is just half cut off, so it's a a medium knock?

Obviously we need to teach them Huffman encoding

They could also just use Knock Code which is a simple way to encode letters as knocks to send arbitrary messages. Most often used by prisoners since it's easy to learn.

Last knock kant be detected to be long or short (right?) so you have to redo it.

3 and 7 are the same sequence. 8 and 11 are a sequence of 4

EDIT: I looked closer and realized these could be explained by simple typos; 3 would be .., 7 is not a typo, 8 would be ..-, and 11 would be -..

Most languages have homophones where the meaning depends heavily on context. You wouldn't start a conversation with "30 minutes" and you likely wouldn't respond to "come here" with "come here" when "my room" is an option.

Yeah for like "meet me out front", there's no real way to do that short knock

The minutes are clearly to be appended to a meeting command, is how I read it. "Come here" alone makes sense. "30 minutes" alone doesn't.

Wow are you really flexing on a kid

Haha I'm jk, that's a really good edit

Shave and a haircut, two bits