Cinch up your sacks, pour a drink, and smoke 'em if you got 'me. As Deadpool would say, "This shit's gonna have nuts in it".
Audio is such a difficult topic online. Some argue it's subjective, while others (like me) go off measurements. Then there's the whole "taste" thing. Some people who have access to an EQ, the first thing they do is make a smiley face. Makes sense, actually, even if it's frowned upon. Our ears and brains work that way. Less sensitive in certain frequency ranges, so we accentuate them to get the desired sound for what we find appealing. Google Fletcher-Munson curve to get an idea. Also have to factor in our individual hearing ability.
Anyway, having had a '96 two door, my first guess is that you're battling a somewhat harsh audio environment right off the bat. In fact, some (like me) will argue to no end that the environment you're listening in is the most important thing. I've heard multi-thousand dollar home theater systems sound like ass compared to far cheaper set ups. Why? Room treatments (to stop reflections) don't usually go hand in hand with aesthetics. So rich folk spend all this money on an audio system that went in a beautiful room with hardwood floors and bare walls. Yay reflections. Dedicated theater rooms can have treatments on the walls and corners, cancelling the peaks and nulls. Outcome? The cheap one sounds better...and also measures better.
So, when you say your audio system lacks finesse, there's a multitude of reasons you could think this. By the way, in the audio world, be it car or home, I do believe in the axiom of "buy electronics for features, buy speakers for sound". Dear God in Heaven I can't count the arguments I've seen where people argue one amp sounds better than another, yet when you ask for data to show how, it's never there. Now, that's not to say that equipment doesn't vary in quality. It certainly can. Especially the speakers.
On a somewhat related note, you ever read where people replaced the "crappy" factory system with an aftermarket rig and thought it sounds worse? Worse to most people means less bass. Know why? Most factory systems that don't use a sub employ full range (or close to full range) door speakers. Meaning the listener was getting close to the full spectrum of sound. When they went aftermarket, where manufactures mostly cater to the car audio enthusiast, they got speakers without checking the frequency response on them. So they replaced speakers that went down to 45hz with ones that drop like a stone at 80hz. Guess what...bye bye bass. Aftermarket speaker makers know that most people who buy their product are gong to use a filter to send low frequency information to a subwoofer (or two). No need to put the extra amplifier strain (hello distortion) running door speakers down to 45hz when that info will be sent to a dedicated sub amp(s).
So..back to your particular issue. You mentioned in an early post that you're sensitive to the human vocal range. Generally that encompasses a surprisingly broad frequency range, but for most, it centers around the 500 -1000hz range. And, interestingly enough, that range is usually the bottom dip that most people make in the aforementioned smiley face on an adjustable EQ. My first thought is that, like you mentioned, "environmental sounds" have caused you to lose hearing in the far ends of the frequency spectrum, causing your sensitivity to the middle of the spectrum. I.e., you simply aren't hearing the other sound information like most people. Especially the high end. High frequency wavelengths are much shorter than low frequency, and are thus are more susceptible to being influenced by the environment you're listening in. Easily absorbed by a seat cushion, the jacket your'e wearing, the headliner, etc. Low frequency info has long wavelengths, making it extremely hard to absorb. It can be a dominating powerhouse in an audio system. It loves to reflect over every surface (because it's not easily absorbed) and reek havoc with the other sounds in the frequency range, altering how we perceive what we hear. Want an example? I knew you did....
Below is a measurement I took not two hours ago. See, I'm having an audio issue of my own. I have quite bad tinnitus. So I take audio and the effect it has on my ears very seriously in any facet of life. I've noticed my right ear (my worst ear) rings badly after even a short trip in my Tahoe. A problem I've not had yet in another vehicle. Look at this measurement at 70mph:
View attachment 216116
That circled area in yellow is low frequency information. For some reason I have an active subwoofer built into my Tahoe. It could be something called Structure borne road noise, it could be that I simply need new tires. Don't know...which is what sucks. Anyway, what I'm showing is that my Tahoe is generating a low frequency sound in some decent decibel ranges. My reason for measuring it was because the clues were there: I had no bass in my radio on the highway, yet I did at idle. Why? The road noise in the cabin is overpowering my radio, unless I turn it up, but then I'm simply doing more damage to my ears by masking the road noise. This could be a more common scenario than most people think. I mean, who measures this shit? Besides me...
I'll stop here. I got long winded. Summary: Car audio and just audio in general can become a rabbit hole worthy of Alice wishing she'd spent more on hiking boots. Maybe post up the exact equipment you're currently running and we go from there. And don't forget the primary source you're listening to. If you're hearing is compromised at the far ends of the spectrum, you're likely going to be sensitive to audio compression, like what's used with SiriusXM. Even though I still use it, it's awful to my ears while my wife can't tell any difference.
To anyone who read all this, damn. You're hardcore. I like you.
*EDIT: And, yes, as others have posted, you can certainly do something to change the listening area. Deaden panels with butyl backed material, closed cell foam, and mass loaded vinyl can do the trick. But it depends on the vehicle. Improvement is always possible but there's a limit some will take with certain vehicles. Don't want to spend $1000 for a fractional improvement.
