A panel for covering and/or soundproofing a wall of a vehicle includes a central layer produced by impregnating a flexible and porous material with a thermoformable resin, then rigidifying the thermoformable resin. The panel also includes two reinforcement layers arranged on either side of the central layer. The impregnation of the flexible and porous material with the thermoformable resin is carried out deep within the flexible and porous material by subjecting a powder of the thermoformable resin to an alternating electric field, the two reinforcement layers being made of a flexible or semi-rigid material.