Drum tuning: an experimental analysis of membrane modes under non-uniform tension

Results of an experimental study of normal mode vibrations in single-headed musical drums under non-uniform tension are presented. Although uniform tension is often assumed in theoretical treatments, in practice the musical drum only approximates this condition, even after careful tuning by the drummer. This study investigates the behavior of normal mode shapes and frequencies under non-uniform tension, as they relate to the tuning process. In particular, the role of the (1,1) mode is described. Experimental results include electronic speckle pattern interferometry (ESPI) images of modal shapes along with the associated frequencies. A finite element model is used for comparison with the experimental results.