Predicting the sound insulation of single leaf walls: extension of Cremer's model

In his 1942 paper on the sound insulation of single leaf walls, Cremer [(1942). Akust. Z. 7, 81-104] made a number of approximations in order to show the general trend of sound insulation above the critical frequency. Cremer realized that these approximations limited the application of his theory to frequencies greater than twice the critical frequency. This paper removes most of Cremer's approximations so that the revised theory can be used down to the critical frequency. The revised theory is used as a correction to the diffuse field limp panel mass law below the critical frequency by setting the nonexistent coincidence angle to 90 degrees. The diffuse field limp panel mass law for a finite size wall is derived without recourse to a limiting angle by following the average diffuse field single sided radiation efficiency approach. The shear wave correction derived by Heckl and Donner [(1985). Rundfunktech Mitt. 29, 287-291] is applied to the revised theory in order to cover the case of thicker walls. The revised theory predicts the general trend of the experimental data, although the agreement is usually worse at low frequencies and depends on the value of damping loss factor used in the region of and above the critical frequency.