Sound and Porsche's air-cooled engines

[Homer Simpson]

Has there been an analysis into the distinctive sound emmited by the old air-cooled engines in Porsche road cars? I know it is a complex mixture of sounds (fan, belts, exhaust, etc), but is there any one single component that dictates the very unique sound of these engines? I remember reading about 2-stroke kart engines, and there was some mention of the cooling fins being resonated as a reason for their (very loud) engine tones. Was this a factor with the Porsche engines?