“…On the other hand, non-parametric methods [ 16 , 17 , 18 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] aim to numerically estimate the acoustic field. In this category, the sound field is typically modelled as a linear combination of solutions of the wave equation [ 27 ], e.g., plane wave [ 25 , 26 ] or spherical wave [ 22 , 23 , 24 , 28 , 29 ] expansions. Alternatively, RIRs are expressed through their modal expansion [ 16 , 17 ] or exploiting the equivalent source method (ESM) [ 30 ].…”