From CT scans to FEM: influence of CAD model complexity on the modal analysis of a small kantele

In recent literature on the modelling of musical instruments, the use of computed tomography (CT) scans has been increasingly explored. Compared to other 3D imaging techniques, CT offers the crucial advantage of enabling full volumetric reconstruction of an artefact, allowing the identification of internal features and structural details without disassembling the instrument. However, less research has been aimed at establishing a standardized reverse-engineering workflow translating CT data into a geometry suitable for finite element vibroacoustic analysis, and it remains unclear whether CT-derived geometries provide sufficient added value compared to simpler models built from direct measurements. In this paper, a pilot study is presented on a small kantele. Three geometric representations are considered: a Detailed model derived from CT data, a Reduced version obtained through mesh decimation, and a Simplified model constructed from direct measurements. A FEM-based eigenfrequency analysis is performed on all three models. The Reduced model shows good modal agreement with the reference, while the Simplified model exhibits substantially larger discrepancies, highlighting the significant impact of geometric fidelity on modal predictions.