Footfall noise from adjacent spaces can lead to occupant dissatisfaction. Constructing interiors to accommodate for footfall noise can greatly reduce its negative impact on acoustic comfort. In common spaces, especially corridors in open environments where there is heavy foot traffic, this feature minimizes disturbances. Footfall noise is characterized by impact insulation class (IIC). IIC of a particular floor assembly is determined from the use of a tapping machine, as described in ASTM Method E492; most flooring products also list the IIC in their specification sheets. The higher the IIC, the greater sound attenuation of impact sound. IIC measurements cover a frequency range of 100-350 Hz; the range corresponds to a general “thump” at the lower level, and a sharper “clack” at the higher end.