IIC ratings cover a limited frequency range of 125 to 4,000 Hz. When footfall noise transfer issues are low in frequency, a high IIC product may not help. When someone steps or stands on a floor, it will deflect under their weight. This structural deflection will sound like a low frequency thump. There are a few ways to resolve this problem:
- Increase the stiffness of the floor/ceiling framing.
- Increase decoupling between the floor and the ceiling.
- Increase the structural damping.