An acoustic noise reduction accessory device is attachable to or integral with a personal computer or other electronic equipment. The device reduces acoustic noise emitted from the rear of the equipment, in particular the acoustic noise from fans. The device comprises an acoustic barrier or shielding member. The barrier is shaped in various forms external to the computer or integrally extending from its back around one or more fans of the computer so as to reduce airflow minimally. Acoustic absorbing material is layered upon the acoustic barrier and may be combined with vibration-absorbing material. The barrier may be shaped from a solid or flexible member(s) to accommodate different-sized electronics and formed to include baffles and structures to direct airflow while absorbing noise. Also it may be made adjustable by one or more slidable members. The device is easily assembled and collapsible for storage.