We have no idea why the sound on YOUR computer does not sound as you expect it to. Have you got a problem with your computer's speakers? Some sound mods have been created on a number of sites like https://www.trainsimcommunity.com/mods/c1-train-sim-classic Anyone playing the same route with the same stock will hear the same sound. But as usual you have a problem but you don't tell us any more than it does not sound as you expect it to.
You could try the sound system from these guys: https://tivolihifi.com.au/products/...xice55QTZeJeG_2UWrQzo8QxOgqKgYFltEFVy0zA8tdpM
Depends on the route, how loud each thing is. What's more important in my experience is that at some point - several years ago - the volume percentage calculation of sound has been changed, quite similar to how in the public version the headlights go off. It might be sound system specific but I found that previously well audible and nicely fading platform audio cuts of entirely just meters away from the platform, easiest to check on München-Garmisch. Also horn used to sound mostly from the mid but not anymore, it's mostly one ear, also the engine sound if you just look to the side by a few degrees. I didn't record to see soundshape but UK locos are generally right ear heavy due to sitting on the left, and US is inverse. Easy to notice if there are multiple seat positions. Judging by the high number of threads posted you are really enthusiastic but be aware, the game is pretty much accepted as-is. If you use enhancements, you should probably use default settings for best results, those are tuned for specific settings and if you play around, you can end up with weird colours. Or sounds.
