Input impedance plays a fundamental role in the acoustics of wind instruments, representing many musical properties. This study investigates both the numerical simulation and experimental measurement of pipe input impedance, focusing on simple geometries such as cylindrical and conical pipes. Through a collaborative effort involving multiple operators, the reliability, reproducibility, and sources of variability in both simulation and measurement processes are examined. The aim is to reflect practices in different laboratories rather than idealized conditions. Numerically, various modeling approaches were used, incorporating different physical models for wave propagation, boundary conditions, and thermo-viscous effects, followed by various discretization methods to solve them (TMM, 1D or 3D FEM, etc.). The presented data are the result of iterative comparisons and discussions. The possible origins of the remaining simulation discrepancies are discussed (implementation errors, numerical convergence issues, or modeling assumptions). Experimentally, sources of variability--such as intra-/inter-operator and intra-/inter-specimen differences, and geometric uncertainties--are analyzed in detail, highlighting the predominance of inter-operator variability. Overall, the study proposes practical recommendations for improving the consistency and accuracy of both impedance simulations and measurements in musical acoustics research.
Ernoult et al. (Thu,) studied this question.