Device for the acoustic insulation of a motor vehicle glazing

A device for soundproofing a plate, includes a soundproofing part and a mounting part, wherein the mounting part is to be mounted secured to a border of the plate, the mounting part being mounted secured to the soundproofing part and having a second thickness hin contact with the soundproofing part, and the soundproofing part is made of a first material, and extends along a first length l in a first main direction, the soundproofing part having a first thickness hof the first material in a direction perpendicular to the first main direction the first thickness hvarying, based on an x coordinate, along the first length l, proportionally to a value of x, wherein n is a real number strictly greater than 1, from a minimal thickness huntil h, the first length l being so that h, is less than or equal to one third of h.