The acoustic role of rosette design in the oud: An experimental study of geometric and mechanical effects

Oud rosettes have traditionally been discussed primarily as decorative structures covering the sound holes, although their acoustic and mechanical roles remain insufficiently resolved. This study investigates rosette design within a unified vibroacoustic framework. The geometric analysis considers total open area, regional open-area distribution, and total aperture-edge length, whereas the mechanical analysis considers progressive added mass and connectivity/stiffness-proxy configurations. A single fully playable oud and a set of interchangeable experimental rosettes were used to isolate local design changes from inter-instrument variability. For each configuration, the structural response was characterized through bridge-mobility measurements, and the force- normalized acoustic response was measured with a calibrated microphone positioned 1 m from the instrument under standardized conditions. The lightweight geometry series produced comparatively modest, descriptor- specific changes; the clearest openness effects occurred at the fully Closed and Open boundary conditions. Progressive added mass produced the most regular downward shift and reduction of the bridge-mobility peak around 220 Hz, whereas the connectivity/stiffness-proxy series evolved non-monotonically and was dominated by the F4 departure. In the experimental oud examined here, the findings support treating the rosette as a coupled geometric and mechanically interacting component rather than as a decorative cover or an open-area descriptor alone.