Ventilation Shaft

This is the sound as recorded from the inside of a ventilation system. In architecture, an airshaft is a small, vertical space within a tall building which permits ventilation of the building's interior spaces to the outside. The floorplan of a building with an airshaft is often described as a "square donut" shape. Alternatively, an airshaft may be formed between two adjacent buildings. Windows on the interior side of the donut allow air from the building to be exhausted into the shaft, and, depending on the height and width of the shaft, may also allow extra sunlight inside.