Not all noise is the same. The sound of your neighbor's TV travels differently than the sound of their footsteps, and each requires different solutions. Understanding this distinction is the first step toward effective soundproofing.
Airborne Noise
Airborne noise travels through the air as sound waves. When these waves hit a surface like a wall or door, they cause tiny vibrations that transfer the sound through to the other side.
Examples of Airborne Noise:
- Voices and conversations
- TV and music (except heavy bass)
- Traffic sounds
- Dogs barking
- Sirens
- Construction noise (some)
How Airborne Noise Enters Your Space:
- Through gaps around doors and windows
- Through thin walls (causing them to vibrate)
- Through windows (glass vibrates easily)
- Through HVAC systems and ducts
Solutions for Airborne Noise:
- Seal gaps: Weatherstripping, door sweeps, caulk
- Add mass: Heavy curtains, MLV, additional drywall
- Create air gaps: Window inserts, double walls
- Absorb sound: Soft furnishings, acoustic panels
Impact Noise
Impact noise (also called structure-borne noise) is created when something physically contacts a surface, sending vibrations directly through the building structure.
Examples of Impact Noise:
- Footsteps
- Doors slamming
- Furniture being moved
- Items dropped on floors
- Running, jumping
- Pets' claws on hard floors
- Subwoofer bass (which shakes surfaces)
How Impact Noise Travels:
The impact creates vibrations that travel through connected structural elements—joists, studs, floors, ceilings. The whole structure becomes a conductor for the sound. This is why you can hear footsteps from two floors up—the vibrations travel through the building.
Solutions for Impact Noise:
- Address the source: Rugs on the floor above, soft footwear
- Decouple surfaces: Resilient channels, floating floors
- Add cushioning: Thick rugs with dense pads
- Isolation pads: Under appliances and speakers
Why Impact Noise Is Harder to Stop
Impact noise is generally more difficult to address because:
- It travels through the structure, not just through air
- Multiple surfaces become "speakers" radiating the sound
- The most effective solutions require addressing the source (not always possible)
- True isolation requires construction (decoupling surfaces)
This is why upstairs neighbor footsteps are such a common and frustrating complaint—the impact transfers directly through the floor/ceiling assembly, and stopping it from below is very difficult without construction.
Identifying Your Noise Type
To solve your noise problem effectively, identify what type you're dealing with:
| Characteristic | Airborne | Impact |
|---|---|---|
| Sound quality | Voices, music, higher pitched | Thuds, booms, lower pitched |
| Timing | Often continuous or prolonged | Usually sudden, brief |
| Location feels | Comes "through" walls/windows | Feels like it's "in" the structure |
| Sealing gaps helps? | Yes, often significantly | No, doesn't address the path |
Many Noises Are Both
Some sounds combine both types. Music with heavy bass creates airborne sound through the air and impact-like vibrations through surfaces. A washing machine creates both airborne noise and vibrations through the floor. In these cases, you may need to address both transmission paths.