Go to a High power, F-Class, CMP-GSm, etc, match where they use pits and you can hear the bullets cracking overhead, even though in many cases you can hear the shot.
In my experience in the pits, you would hear a "Tick" as a 5.56 bullets zipped through the target overhead of your pit position followed by a "Pop!" of the AR's report. If you were distracted, you could easily miss the sound and as a result would be slow on pulling the target down. (A late pull can throw a shooter off, so it behooved you to pay attention because that shooter is likely going to pull your targets.)
Next was a "Tack" sound when a 7.62 zaps through and a "POW!" of the M1A's report.
But I pulled for Garand shooter once: the first time you hear that, it really gets you attention...the paper makes a distinct "TOCK" sound when the shooter sends one through the target, followed by the "BOOM!!" of the M1's report.
Once you hear them together, you never forget the difference.