In Silom, Thailand, I was eating in a small restaurant, 5x10 square meters. It is not a quiet place since it is located nearby the road. However, customers in here, for example white people and Thai locals, normally speak very low and leave after they finish. But 10 Chinese tourists came in and started ordering food, talking loud, like shouting. Their loud voices made me very nervous. No idea if they will talk to local people with the same sound level or not since they use hand method to order.
Direct translatation from English of
Lower your voice please to Chinese is
请降低你的声音. Is it ok?