The table below gives the STC ratings for 3-in-thick dense concrete (12 lb/ft ² per inch of thickness) and for three successive doubled thicknesses of 6 in, 12 in, and 24 in.

Mass law follows the law of diminishing returns. As shown by the above data, the STC of a homogeneous construction increases about 5 for each doubling of weight. However, it is the initial doubling that provides the most practical improvement. Each successive doubling produces proportionally less STC (or TL) improvement per unit weight and a greater increase in cost per unit STC (or TL) increase. Consequently, complex constructions are required when it is necessary to achieve high STCs and TL improvements, especially at low frequencies. The graph below shows transmission loss performance for 3-in-thick and 12-in-thick concrete.