Instead of hollow-core doors, you need solid-core doors. They look like natural wood and provide much better sound resistance while being more sturdy and durable.
Filled with engineered wood instead of real wood, solid core doors offer the strength, insulation, and soundproofing of a solid wooden door without the hefty price tag.
Solid core doors are easy to maintain, as solid wood doors are vulnerable to warping, while hollow doors are vulnerable to water damage and general impact damage.
A solid core door can cost from $100 to several hundred dollars. At this sweet spot, solid core doors give you good value for your money because you can rely on their quality.