In many cases, the sound that is associated with a fan or airflow noise radiates outward from the ductwork into the adjoining space. This radiation is called "breakout noise" by the HVAC industry. Breakout noise can be a problem for duct systems because it causes noises in rooms where there may not even be an air vent. This can be a significant problem for rooms that are located near a sound source (like a fan, compressor, or roof top unit).