Standard insulation parameters can often be misleading when dealing with heavy urban noise dominated by low frequencies. To correctly select barriers that protect against traffic, engineers must refer to a corrected indicator that takes into account the specifics of the surrounding bass sounds.

The single number describing the sound insulation of a wall (e.g., Rw) is often too much of a simplification given the diverse sources of noise. We insulate differently from neighbors' conversations than we do from street traffic. The index that takes into account adaptation C allows for a precise selection of the partition for a specific type of residential noise.

Standard acoustic insulation parameters of ceilings often do not fully reflect the nuisance of footsteps or moving furniture. To make the assessment more consistent with the actual auditory perception, engineers use special mathematical corrections. The spectral adaptive index is the key to understanding how the ceiling copes with low frequencies generated by footsteps.