That stuff is so easy to manufacture and tamper with. I have a relative who could make it sound like a single shot or 30 shots if you gave him the original. I’ve seen him slide and dice audio broadcasts with specialized software where there’s no way you could tell the difference. He can cut any imperfections in the recording and can put layers into it then compile them on a mastered recording where it would fool the best listeners.
Wonder if it’s the same people who manufactured the birth certificate? I hope so...
The software that will do everything you mentioned is called "Cool Edit" (It may have a new name now that Adobe has bought it)
With my cheapo music keyboard I can. become a complete orchestra.
Needless to say,someone well acquainted with it can do a lot more.
Audio of any kind should NEVER be accepted as evidence.