Impact Noise

 

Impact noise occurs when an object collides with another object, and you usually hear it from the floor above you. Examples include footsteps, a chair sliding across a wood or tile floor, or an object falling on the floor. Impact noise travels freely through a structure and through air pockets. The diagram below illustrates all the pathways that impact noise travels through when a ball hits a bare floor.

REDUCING IMPACT NOISE

The best way to protect reduce impact noise is to stop it at the source, before it has a chance to travel. Here are some tips:

• Carpet and Pad. By absorbing most of the energy caused by a falling object, a soft carpet and thick pad cushion are perhaps the most effective tools in controlling impact noise, especially at mid- to high-frequencies when noise can be at its most annoying. In many cases this is all you need to take care of impact noise problems from above, however this solution is less effective for isolating low frequency noise. It’s important to note that carpet and pad will do very little to reduce airborne noise.
• Resilient Underlayment.Resilient underlayments made from recycled rubber mats, rigid fiberglass, foam, cork or other materials have much the same effect as a carpet and pad. By absorbing energy they are effective in reducing mid- to high-frequency impact noise. If the underlayments have mass (i.e., rubber) they will also provide some benefit for airborne noise.
• Resilient Mounts. Hanging resilient channel, or Green Glue Noiseproofing Clips (or other modern sound clips) or spring ceiling hangers from the ceiling can greatly reduce the impact noise from the floor above. Installation of such products will always require removal of the existing ceiling to avoid the triple leaf effect.
• Green Glue Noiseproofing Compound. Applying layers of Green Glue Noiseproofing Compound to the floor above is effective at damping airborne noise, but NOT greatly reduct impact or other structure-borne noise. The compound dissipates the vibrations caused by sound waves as they move through a structure. The compound is applied between two rigid materials (for example, OSB subflooring), and unlike other noiseproofing options, it reduces noise at all frequencies.
• Insulation is Important for airborne noise, but does little for impact or other structure-borne noise. To help reduce airborne noise from traveling between rooms, you should always include insulation in ceiling cavities.