What asian cultures always seem to yell when they speak and why?

I'd probably say Chinese or Vietnamese. It's cultural in Chinese to use a loud voice and be sort of forward/blunt with your words, while in Japanese culture it's VERY important to use a polite voice and be respectful/formal.

hm? i don't think it's japanese you're reffering to we never raise our voices or yell.. i speak korean too and lived there for a year i also didn't notice the yelling.. but vietnamese and chinese through to thai seem to talk pretty loudly they're much more brash i think yeah it's a cultural thing and also chinese words sound naturally very harsh because they're short ' ni hao ma ' hello/how are you 'wo de ming zhi shi' see how the words are so short it sounds harsh