Modal Testing of a Soprano pan using a 3D Laser Doppler Vibrometer

Modal testing is a well established technique used to extract modal parameters such as natural frequencies, modal damping factors and vibration mode shapes from structures. Here, the technique is applied to a relatively new percussion instrument – the steelpan. The steelpan also referred to as the Caribbean steel drum or pan originated in Trinidad and Tobago during the Second World War. In this work modal testing is conducted on a soprano pan so as to obtain resonant frequencies and mode shapes as well as to provide a spatial illustration of modal tuning in the instrument. A soprano pan was excited with a periodic chirp signal from a loudspeaker and its response recorded by a 3-Dimensional scanning laser Doppler vibrometer. The results exhibit the nearly harmonic relationship among tuned modes in each outer note. There is also significant modal coupling between adjacent notes that have harmonically related frequencies.