Reduce sound transfer through doors
Rubber air seals along the bottom will be your best bet. An automatic bottom seal may work slightly better, but its a very slight difference over a properly installed gasket seal.

Make sure your door is perfectly balanced in the frame before installing a gasket. You need to make sure the gap is uniform across the entire bottom of the door.

Foam tape would work just as well across the top and sides, and may be cheaper depending on what bottom seal you choose.

Its worth mentioning, unless you have an inch or more gap, its unlikely this extra gap-seal is going to solve the underlying issue. So much of the sound is still going to be transmitted through what are most likely uninsulated interior walls. Soundproofing tends to be a project that just keeps going.