Strip with acoustic damping properties

eq eqA method of manufacturing an assembly including a strip inserted between two substrates, the strip being formed from at least one damping material, includes providing the two substrates; providing the strip; evaluating equivalent real stiffness per unit length K′of the strip and of the equivalent loss factor tan δ; and manufacturing the assembly by inserting a strip having an equivalent real stiffness per unit length of at least equal to 25 MPa and the equivalent loss factor of at least 0.25 between the two substrates.