Device for limiting propagation of acoustic waves emitted by e.g. engine into cavity of longitudinal member of car, has screen placed in and sealing longitudinal member, and shaped to focus incidental acoustic waves on absorption unit

摘要

The device has a screen (1) placed in a hollow body i.e. longitudinal member (4), by sealing the body, and shaped to focus incidental acoustic waves (2) on an acoustic absorption unit (6). The screen is a curved wall with a parabolic profile, or a parabolic cap or formed by a succession of plane/curved segments. An opening plane of the curved wall is inclined with respect to a direction of propagation of incidental acoustic waves. The unit is fixed on an inner face of a part of a side wall of the body. The unit includes a layer of acoustically absorbing fibrous, porous and/or foaming material.