I agree. I believe that Chinese people are a loud bunch. Making an acceptable level of noise is a shared responsibility in a happy social gathering, given it to be a wedding or a birthday party. This is probably the reason that many Chinese restaurants do not have carpets, so to make the noise even louder. So, yes, Chinese people are pretty loud.
However, let's differentiate Chinese people and Chinese language. To many people's surprise, Chinese is not the loudest language. I find it especially true during the everyday commute. Chinese people are so quite. When they are with their children, they try hard to make sure their children stay quite too. When they talk, they talk quietly to each other. One day I was on the ferry with around fifty primary students. They were so quite that I hardly noticed them. But it is not so with English. English is the loudest language.
Chinese people like to sit closely when they talk to each other. But English speaking people like to sit miles apart when they talk to each other. I see that in the movies as well as in real life. Two people sit across the aisle or several seats apart and talk. If they don't speak loudly, the other party won't be able to hear him/her. If there are kids around, you can always hear the loudest kids are the English speaking kids. One day I was in Japan, standing with hundreds and thousands of Japanese people waiting to get into the royal palace, the only language that broke the quite surrounding was English.
It could very well be my personal bias. Given at least a thousand different languages worldwide, I really have no way to make any kind of firm conclusion. But what I can not forget is that one day on the ferry, I was sitting a few rows away from a loud screaming kid and a few loud people, and guess what, they were all speaking English. I am sure they would all sit and eat quietly in a dim and well-carpeted western restaurant.