Install a device meant to prevent babies and children from slamming their fingers in doors. Such products typically prevent doors from closing all the way, so this approach may not be appropriate if the bedroom residents require noise isolation or privacy. That said, if door-slamming is a major problem — if, for example, you rent an apartment and your landlord has warned you repeatedly about your kids slamming their bedroom doors — anti-slamming devices that prevent door closure may be a small price to pay for the peace of mind you will gain from not having to worry about being evicted.
Outfit each of the doors that tends to slam with a door closer — a device that controls the rate at which doors close, preventing doors from slamming shut or banging open. Door closers are commonly used in schools and on screen doors, such as those found on porches and back entrances. Both high-tech and low-tech door closers are available, with low-tech closers on the lower end of the price spectrum.
Take the doors off their hinges and replace them with a quieter, nonslamming barrier, such as a fabric curtain or a beaded curtain. Store the doors or repurpose them into desks or other furniture. While this is a drastic measure that many people would skip, it may be useful for people unconcerned about noise isolation.