Sound‐transmission‐loss tests in accordance with ASTM E90‐70 were conducted using steel‐stud partitions with a single or double layer of gypsum wallboard on each face of the studs. These test results were used to investigate the effect on the acoustical performance due to number of layers of gypsum wallboard, the installation of cavity absorption of different types and thicknesses, the size of stud, and the thickness of wallboard used. These test results have been summarized in two ways. First, to offer a method of calculating the change in STC due to changes in the components of a partition of known STC ratings. Secondly, a table showing the effect on the TL values due to each of the changes.