The sonic crack sound effect is being played when the bullet passes too far from the player's ears. For distant super-sonic ripping through the air a sound effect more like that "feeeeOOOOOO" used in Operation Flashpoint would be better.
- Legacy ID
Here are a couple of Google matches where this has been discussed previously for other versions of the game, once by me and once by DSL:
It depends on which direction the round is travelling...
As long as the projectile is aiming generally in your direction (towards you) the pressure waves will still be compressed creating the high pitched sonic crack and will be audible in different locations so it is absolutely correct as it is.
No need to change it :-)
The sonic cracks are a result of the supersonic pressure wave the supersonic bullet creates. It will be audible to any unit towards at which the bullet is travelling, even if you are just in front of the barrel and someone fires their weapon behind you.