Q: What is "Drilling"? Does it have anything to do with BR?
(Answer by @Pacifico)
A: Drilling is when you work on specific issues you have rather than full PTs. You should BR when you drill but BR itself does not ...
That used to happen to me sometimes too.... The audio would be normal if the speed was x1.0 or x0.8 but if I sped it up it would get this metallic echo splintering the audio. It usually went away if I refreshed or reloaded.
If you choose the incorrect answer on BR that means you need to go back and review that question - there is a good chance that either you are second-guessing yourself too much, or you may have an issue with the underlying content of the question.