"I would have thought that in a culture with so many people, you'd likely be careful about sharing your sounds with others."
Your first visit to China?
Actually, this is one of those times when being a foreigner helps. While Chinese are usually reluctant to interfere in other's pleasures, you as the barbarian are perfectly free to do so. Particularly in hotels I always seem to be asking other guests to close their door when chatting in their room or not talk on their mobiles in the hall, and I haven't been murdered for doing so yet.
I think Chinese are impervious to sounds. A couple of years ago, I was in a cheap hotel in Shanghai. Two of my neighbors, who had seperate rooms, were playing cards in one room. They left the empty room door slightly ajar, and the alarm beeped for a good 5 or 10 minutes, before I went out, accessed the situation, and just closed the door to the empty room and went back to bed.