The sound insulation of separating masonry cavity walls is partly determined by the number and the dynamic stiffness of the wall ties used to connect their two leaves. All wall ties conforming to current British Standards have a drip to prevent water passing across them from the outer to the inner leaf. The presence of these drips means that the dynamic stiffness of the wall ties cannot be calculated from their dimensions and material properties. In addition, the dynamic stiffness depends on the width of the cavity in which the wall tie is used. Therefore, the dynamic stiffness of wall ties needs to be measured experimentally. This paper describes such a measurement procedure. 6 pages.