Abstract: An acoustic board with an improved composite structure (1), suitable for reducing the sound of aircraft engines, wherein an upper layer consists of a fabric (7) having a high sensitivity to sound velocity and a supporting sheet (4) having a certain porosity; the upper layer is combined, in turn, with an intermediate honeycomb layer (2) and with a lower layer (5) of the conventional type.

Abstract: An acoustic board with an improved composite structure (1), suitable for reducing the sound of aircraft engines, wherein an upper layer consists of a fabric (7) having a high sensitivity to sound velocity and a supporting sheet (4) having a certain porosity; the upper layer is combined, in turn, with an intermediate honeycomb layer (2) and with a lower layer (5) of the conventional type.

Abstract: A sound-absorbing and reinforcing structure for engine nacelle (20) acoustic panel (24) designed to contain, in particular, jet engines for jet aircraft; each acoustic panel (24) has an inner layer (32), which is perforated and made of composite material, an outer layer (34), which is not perforated and is made of composite material, and an intermediate layer (36) made of a honeycomb structure pressed between the two previous layers. At each longitudinal joint (40) of the structure, the layers (32, 34, 36) are connected to a butt strap (35) by means of a series of connecting members (38) which ensure the continuity of the fan flow and maintain in position a portion (36A) of a layer that is honeycomb-structured and acoustically treated, the said portion (36A) contributing to the strength of the joint (40), and hence to the strength of the entire structure.