This is Asia's smallest owl at around 6.25 in /16 cm.
I've seen comments that it calls in all directions, making it a difficult owl to locate by sounds. Here is a video of it hooting all around. It's a pretty cute sound.
Though that hoot sounds like that time I got my nephew and niece a train whistle as a souvenir (there’s a historic train that runs along the WI side of the St Croix. Nice scenic ride on an old train.)(yeah, their parents made sure to “lose” the train whistles real quick……)