I believe this arises from the Dynamic compression used by the Sound engine. This was an improvement made in the early DCS days and one I've hated ever since.
It Dynamically normalises the Volume of Sounds in the game world. It is like the compression used for the "Loudness wars" on digital music. The Most dramatic effect of which can be felt on the Supersonic Boom of an aircraft Flyby.
In LockOn this was a thunderous Boom, with plenty of Dynamic Range between quiet and loud, in DCS it sounds like a wet fart. The Current sound engine normalizes quiet sound up in volume and noisy sounds down, in real time, in order to avoid clipping.
This strips all sound in DCS of all Dynamic range, removing detail from the sound-scape and produces oddities such as Sound Radar.
From Speaking to c0ff about this very issue (quite some time ago though), it is unlikely to be fixed.
Nate