Just experienced this crackling yesterday, and I tried all the solutions I saw online. It was only until I removed apps like Mac Keeper and such that the sound disappeared, I'm not too sure if it's permanently gone but we shall see.
McOphe101
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
User for