Although it may seem a little collegiate, having something like "quiet hours" or "courtesy hours" are not particularly uncommon in a complex. These are times when people should pay extra attention to how much volume they are making and generally take place at night. For example, asking people to be extra quiet from midnight until nine in the morning during the weekend but from nine pm to nine am during the rest of the week may be perfectly acceptable. The rest of the time, especially if you are having noise complaints, maybe just remind your residents that people can sometimes hear each other and keep an eye on how loud they are being.
Another thing that you may want to put up hours for is the laundry if you have some on sight. For example, my current apartment sits right on top of my building's laundry room and as a result I can always hear when someone is doing a load of wash. Although I understand that doing wash at two in the morning is sometimes a necessity, I certainly don't like being woken up by a machine kicking on. There are some people who sleep very lightly and it can be a cause of contention if they are woken up like this. Post hours of use in your on-site laundry room and hopefully your residents will follow them.
Although no one really likes to have schedules placed on them in regards to their housing, many of these things are rather small and are based off of common courtesy. As a result, most people will not mind small things like this but it certainly doesn't hurt to remind your residents that they may be doing something that can disturb others around them. Try having small schedules for those who live in your apartment buildings and complexes and see what everyone things about it.