When a sound wave hits a hard, flat, non-porous surface, most of its energy bounces back — the same way light bounces off a mirror. Concrete, glass, tile, and hardwood are all strong reflectors of sound.
Soft, porous materials work differently — instead of bouncing sound back, they convert some of that sound energy into a tiny bit of heat. Carpet, foam, curtains, and upholstered furniture all absorb sound rather than reflecting it.
| Material | Reflects | Absorbs |
|---|---|---|
| Concrete / brick wall | Very high | Very low |
| Glass window | Very high | Very low |
| Hollow-core door | High (but transmits easily too) | Low |
| Carpet | Low | High |
| Acoustic foam panel | Very low | Very high |
| Heavy curtain / blanket | Low | Medium-high |
| People, upholstered furniture | Low | Medium |
In a hard, empty room, sound reflects over and over before it finally dies out — this lingering, bouncing sound is called reverberation. Add soft, absorptive materials (people, furniture, carpet) and each bounce loses more energy, so the sound dies out faster and the room feels calmer.
Sound doesn't just bounce around inside a room — some of it also transmits straight through the wall, door, or any gap into the space next door. This is a completely different mechanism from reflection or absorption, and it's almost always the actual cause of one room's sound "bleeding" into another.
The most common transmission culprits in a real building: a gap under a door, a hollow-core door (thin and lightweight, so sound passes through easily), and a shared wall that isn't especially thick or dense.
Try building a fix plan below. Watch what happens to your budget, and whether your plan actually includes something that blocks transmission.
Check off fixes and watch your running total against a sample $250 budget. Each fix is tagged by what it actually does.
You now have everything you need to diagnose a real bleed problem and propose a fix that actually addresses it. Head to the Problem page to get started.