A viscoelastic plastic interlayer intended to be incorporated between two glass sheets to form a laminated glazing with vibro-acoustic damping properties, the interlayer comprising at least one layer made of viscoelastic plastic with vibro-acoustic damping properties, the interlayer being such that the resonant frequency f2 of the second resonance mode of a laminated glazing bar with a surface area of 25 mm×300 mm composed of two glass sheets each 2.1 mm thick, between which is incorporated the interlayer, determined by measuring the mechanical impedance (MIM) at 20° C. according to standard ISO 16940, is between 760 Hz and 1000 Hz and the loss factor η2 of the second resonance mode of the same bar, determined by MIM under the same conditions, is greater than or equal to 0.25.