The cheapest way to soundproof a ceiling is by using acoustic foam panels. You can either buy them pre-made or make your own out of insulation batting and fabric. The downside of using acoustic foam panels is that they only treat noise from one direction (directly below). So if you have noise coming in from other sources, you'll need to use additional measures to treat those sounds as well.

There are a few ways to soundproof a ceiling, but the cheapest way is to add some acoustic panels. Acoustic panels are made of materials that absorb sound, and they can be installed in a few hours using basic tools. Another option is to add some insulation between the floor and the ceiling. This will help to reduce noise transfer between floors, and it will also help to keep your ceiling cooler in the summer and warmer in the winter. Finally, you can install a soundproofing border around the edge of your ceiling. This will help to prevent sound from traveling through walls and other surfaces.