This is my first summer in Korea, so lately I've been hearing weird sound nearby trees.
It is very loud and sometime synchronizing with each other; at a time.
Later it became quiet for a while, and then, the sound will come back.

This sound is almost everywhere, outdoor.
Especially when there's tree nearby.
It was hubby who pointed out "Is that cricket?"
"But this is louder and more weird." Hubby continued.

Since that day, we made assumptions that there's recorded machine thing that they put near each tree to feel like summer.
We have high imagination, you see...

Yesterday, near my university, I heard it again.
So I asked my friend who is from Panama.

Me : "What's that? It's everywhere."
Friend : "What sound?"
Me : "Hear that loud sound or noise? Is that a machine recorded sound?"
While laughing; Friend : "It's shikayda.."
Me : "Shi what?"
Friend.  "C-I-C-A-D-A. You don't know that? I thought it's everywhere"

I'm not sure if I've heard this sound back in Malaysia.
Probably, yes, but not as loud and synchronize at a time then pause, later to resume back.

So for those who doesn't know about Cicada, like me.
This video is similar but the one I heard is less noisy and it stops occasionally.