What I said was HD has their sound trademarked, and I consider it frivolous.
It's still one of those "chicken or the egg" type questions, since you can't copy the sound, without copying the engine design, almost verbatim. Unless of course, you "fake the sound" via modification of the exhaust system. Were a maker to do that, so as to infringe on Harley's customer base, then trademarking the sound of their bikes make an eminent amount of sense. That's whether your tender ears agree with it, or not.
And that Ford's Mustang sound is fabricated, which I also consider frivolous.
Well, maybe, maybe not. The street level noise level is, (whether you admit it or not), directly interpreted by other humans as an indicator of how much power is being produced.
Or to the contrary as we sometimes scornfully yelled at cars with glass pack mufflers, but without any other obvious performance enhancement, "it must be fast, listen to all the noise it makes".
All of this is based on the animal side of our nature. The human male doesn't have the plumage of a peacock, the roar of a male lion, or the trumpet of a bull elephant. Accordingly, he feels the necessity to create by any means necessary, sounds and images based in nature, to attract a mate. (Or at least, a mate for the night).
So, the louder the roar, becomes, (perhaps subconsciously), it becomes interpreted as, the more masculine the male. Which, I would assume you would find extremely offensive, because of your deep affliction with, "Sheldon Leonard Syndrome".
Now, as for Ford "faking the sound of the mustang", you still have to keep in mind that the less restrictive an exhaust system is, the louder it will be. The work Ford may have performed on their car's exhaust, could more correctly be termed as "altering the tonal spectrum", or "equalization", as it's more commonly called. It's very simple, you filter out the yapping bark, but leave the robust low frequency growl. So instead of the yipping of a Chihuahua, you have the growl of a tiger.
Since I come from "the muscle car era", we used to interpret the mods and performance potential of a car's engine an entirely different way That's by judging how it idled. Fluctuating idle speed, along with an overall roughness, indicated the amount of "cam" that was in the engine. In other words the camshaft's lift and duration is a predictor of how well the engine will perform in the upper end of its RPM range. High lift, and long duration camshafts, allow both the intake and exhaust valves to be open at the same time, which in turn causes the rough idle. At high RPMs, the exhaust leaving the engine actually has "a poor man's supercharger effect", by allowing the incoming fuel mixture to be sucked into the engine by the exiting exhaust pulse rarefaction.
If this interests you, (which I doubt), you can read this article from the university of Colorado, about the underlying math:
https://www.engr.colostate.edu/~allan/fluids/page7/page7.html Frankly, I can only manage algebra while I'm still in the algebra classroom. Perhaps you'll fare a bit better.
You do know that car companies spend millions of dollars in research on perfecting the sound of their car doors slamming, don't you? By your definition, their door slams are "fake".
But once in a while, you do surprise me by actually reading one of my posts with attentiveness.
Let's face it, sometimes they're long enough a person has to skim.a bit.
I think they are obnoxious whenever I hear them. Then again, I am extremely sensitive to sounds.
You know, I don't even have speakers attached to my computers, since the noises made by Windows are so obnoxious, at any volume.
However, I can tolerate music that I enjoy at ungodly high volumes for extended periods of time. Inversely, I need earplugs when I'm exposed to rap, punk, and disco.
I'm good to at least 110 Db on this though. Give it a listen. Let me know what you think:
The female vocalist, Floor Jansen, is widely regarded as the most versatile and likely the best girl singer in all of this genre, which is, "symphonic metal"
Too much? This is (only very slightly) tamer
The second track, "The Haunting", is an adaptation from Goethe's "Faust",
(*) where the devil tricks Faust into thinking he is the hero's dead girlfriend. Jeez, those guitars are noisy though. Did you pick up the key change at 2:46?
(*) I didn't want you to think this was just some illiterate wanking by some heavy metal Harley driving thugs.