Incremental optimization of inharmonicity using sensitivity curves. For the upstream register hole, L _h is increased from 4 mm to 8 mm. For the downstream hole, R _h is reduced from 1.4 mm to 1.2 mm. Thin colored lines represent the initial inharmonicity of the saxophone, prior to any parameter modifications. Black lines indicate the estimated correction obtained using first-order sensitivities [Eq. (11)]. Thick colored lines correspond to the inharmonicity computed by directly solving equation (2) with the modified parameters.