Sound absorbing panel particularly for aircraft engine

The sandwich noise insulation panel for an aircraft has a reinforcing layer (10), a reflector (12) and a frame (14) between these to form cells (16) separated by partitions (18). Separators (20) in the cells each have a circular peripheral wall (20a) and positioners (22) for he separators in the cells. The positioners are attached to the separators and engage against the partitions.