Not much to say about this episode but I do hope you enjoyed it. It was fun watching, it's light, meant to be the "calm before the storm".
But two things, though I think these were touched on before still good examples and as a reminder.
1. "How did you get this case?" And Young Woo was confused.
A very common trait or quirk from majority of autistics. If you suspect a person is autistic, try to rephrase the question.
2. "The clock is too loud." (among other things)
This has to do with sensory sensitivities. Young Woo's hypersensitivity is hearing since episode 1. It is why she always have headphones with her.
Q: Is it possible she heard the small clock located at the far end of the living room and while the door of their room was also closed and she's at the far end of their room?
A: Yes. Autistics with hypersensitivity in hearing can. Young Woo's is not that high, otherwise people walking would bother her too -- frequently. But her hearing is hypersensitive.
Mine is similar. Ticking clocks are the bane of my sleep too. Water droplets, same thing--think of a faucet that was not closed 100%. When I was a kid, I can even hear a needle dropping on the floor. It also affects us differently. Even though we both have hearing hypersensitivity,
Young Woo starts to overload when there are loud noices and people shouting; I don't, it does affect me but I can keep it under control. I get bothered by water droplets more than ticking clocks because I learned to block the latter but can not block the sound of water droplets -- still it can wake me up because once asleep, I'm no longer actively blocking the sounds.
Going back to my earlier explanations in the previous episodes, even if we have similar traits and quirks, it does not mean the level of effect or intensity. It may even be the same degree but it affects us and we react differently.
So, there you go. Yes, hypersensitive hearing is real. It is both a pro and a con.
BONUS: One last thing, not because an autistic person has hypersensitivity in hearing does it mean they'll "hear" you talking or even respond back. The thing is, as mentioned before, a lot of things are going on in our mind, we literally do hear you (more than half the time) but processing what we heard takes a back seat more often than not.
Remember when a person asks Young Woo again and she pauses, thinks, and say "huh? Ahh!" She tried to remember what she heard, processed it, and "aha moment". Some say it's attention related but I disagree, it's more of prioritising which inputs we process first. Anyway, this is a whole different and lengthy topic.
Always remember, autism is a four-dimensional spectrum, not a two-dimensional line from left to right.