Abstract: The invention provides an elongate turning vane for altering the direction of air flow in a duct, such as a wind tunnel, where the vane includes a device for attenuating sound propagation past the vane. The vane has extreme ends mounted to opposing sides of the duct, a longitudinal axis and an aerodynamically efficient profile. The vane comprises a rigid core having air permeable upper and lower surfaces, preferably a welded assembly of two perforated sheet metal plates with transverse profile plates, with vent holes, to provide the appropriate shape and venting. Two sound attenuating panels have interior surfaces bonded to the upper and lower core surfaces of the core, and exterior surfaces defining suction and pressure surfaces of the vane. Vent holes provide for passage of air axially within the core between the duct and the core surfaces. Venting is required to balance the air pressure on both sides of the sound attenuating panels to prevent distortion of the panels bonded to the core.