The IIC rates floor-ceiling structures in ascending degrees of impact sound insulation. This measures the attenuation of foot fall noise transmitted to the unit below. IIC values increasing in magnitude indicate an increasing degree of impact sound insulation. Typical values of IIC range from 50 - 60.


We use a Norsonic NPR-2011 calibrated tapping machine compliant with ASTM E-492 and ISO 140 part 6 and 7.


To determine IIC:

  1. Several positions are chosen at random on the sending room floor. The tapping machine is oriented at 45 to the direction of the beams.

  2. Background measurements are taken in the receiving room.

  3. Start the tapping machine. Sound levels measurements are taken at several random positions in the receiving room.

  4. Move tapping machine at repeat.

  5. Reverberation times are measured in the receiving room.

  6. The IIC is calculated per ASTM E-989.