Great post!
A couple of things come to mind re sound in COD:
Intake growl: when you increase boost by opening throttle in a carberetted engine, this would become a roar in the pilot's ears. I ride an older carb'd Harley (they're all fuel injected now) that's been bored, stroked, hot(ter) cams, heads ported & polished, and the carb itself replaced by the stock 38 mm bore to the present 44 mm bore. The intake is by my right knee. When I roll on throttle (increase manifold boost) the exhaust note definitely change, as does the (very) audible intake drone -- which DOES become a roar to both my ears and one particular overzealous Ontario Provincial Police officer.
I believe the intake roar emphasizes the deepening exhaust note with increased boost (vs increased rpm's) per your fascinating post above.
The second note is exhaust sound, at least the external Merlin note -- which in CoD it ain't. External start up and idle are great, internal cockpit sound credible....but external cruise (F2 key) or fly by (F3 key) is closer to an 18 wheeler truck diesel. We are all collectively "sighing for a Merlin" (with apologies to Jeffrey Quill!).
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