Ahha, but can you honestly tell me you can not tell a Road Star from a Road Glide when you can't see either? I sure can. Road Star is water cooled, Road Glide is not!
I hear exhaust notes and other sounds of different machines. This includes the different pitches and notes of the various sizes and pitches of cooling fans on different automobiles. I don't hear the cooling system on a Road Star though, because it doesn't have one. The Royal Stars are wet bikes though. With their odd little cooling boxes up front there is a sound. But not one I'd hear above the expected exhaust note of a Harley. The engines and their induction systems sound entirely different; that's true. But that's exhaust and other mechanicals. I don't really "hear" the cooling system. Especially from whatever barriers from a distance outside a secure testing area such sounds might have been heard from.
Goldwing might be a better comparison. With their quiet exhaust I can, if I listen closely, hear the whir of its water pump as a distinct sound. I've got to be close and the engine has to be wound down. It's fans make a distinct sound also. But, again, not one I can hear with even Goldwing exhaust if the engine is wrapped up much.
In fact I might hear the lack of enough other noises that denote an air cooled engine that I might assume water cooling. But I've never "heard" the water cooling on a street cruiser or tourer from any distance or over any other pretty normal ambient noises. So, unless this prospective 2015 test mule Road Glide has cooling fans that could be heard behind whatever barriers made up its secure area that were then relayed anecdotally to the salesman I'm still wondering what the sound was of the water cooled Road Glide.