Abstract: Disclosed is a noise insulation device for aircraft, comprising a first opening that is delimited by a series of conducting surfaces whose inner edge is oriented towards the interior of the noise insulation device from a horizontal cross-sectional perspective and whose outer surface is directed towards the side, a roof, and a second opening which is located opposite the first opening and is delimited by walls. The inventive noise insulation device is characterized in that the size of the second opening can be modified by making changes to the walls.