Abstract: A noise reduction hood for attenuating the acoustic noise of cooling fans emanating from an electronic enclosure. The hood is comprised of a base that is constructed and arranged to be supported on the enclosure. The base has an air duct that is adapted to pass air therethrough in a first direction, and includes at least one noise reduction panel disposed in the air duct to attenuate acoustic noise emanating from the enclosure. In one embodiment, the noise reduction panel divides the air duct into a plurality of acoustical flow passages extending through the base. In another embodiment, the hood includes a cover, which may be detachable, that is adapted to divert the air from the first direction to a second direction. In a further embodiment, the hood includes a rim extending from the base for surrounding a portion of the enclosure to secure the hood to the enclosure. The hood may include a plurality of interlocking panels that are arranged in a grid pattern to form an array of acoustical flow passages.