This is an audio recording titled "Heat Duct_042697". The soundscape is dominated by the hum and rattle of a heating duct, part of an HVAC system. The rhythmic drone of the heat being pushed through the ductwork creates a consistent backdrop. There are additional sound effects or 'sfx' layered on top, subtle yet enhancing the overall auditory experience. These include occasional creaks and groans of expanding metal, echoing the heat's intensity. This audio truly encapsulates the raw essence of a functioning heat duct, bringing an otherwise overlooked sound to the forefront.