I forgot to mention the version in my original post. Initially, I (re)installed it in RF Evo.
Later I tried it in RF9.5 with better sound results. The "crackling" only happened at the beginning of the flight and a few times at the end of the flight. I did immediately notice that the scenery in general was less nice in RF9.5, and it seemed that there was a lot of "lightning" type flashing in the clouds from the 11 o'clock to 3 o'clock positions. I figured that your fine work might not be backward compatible, so I uninstalled it from RF9.5
Although I have been simulating RC flight sporadically since RF6, I only began tinkering with adding a plane or scenery to RF9.5 in the last 4 months. I have no experience with editing sceneries or aircraft at all in RealFlight series. I just bought RF Evo last week.
I will follow your audio edit suggestion and report back.
EDIT: No change in results after following the settings adjustment.