I am experience an issue with audio in FCP X. In my videos, I take certain sections, turn the audio down to zero and speed the sections up to 8x. What this often does is screw up the audio in the entire video. It becomes choppy and echo-y and, occasionally, the echo is so strong that it sounds like there are two people talking at the same time.

An example of the issue can be seen in

. There are several places where the acceleration happens (e.g you can see one at the 25min mark). But you can hear the choppy sounds throughout and especially after that mark.

Any suggestions (short of switching to Premiere?)

  • For a more extreme example, see youtu.be/cf8rgx60IKA?t=13m20s
    – Wynne
    Commented Oct 31, 2017 at 21:37
  • Additional information. I did more testing and concluded that this is caused by the combination of speeding the clip up and preserving pitch. If I don't preserve the pitch, then this distortion doesn't happen. (But I need to preserve pitch or else the speed up transitions don't work.)
    – Wynne
    Commented Nov 1, 2017 at 2:01
  • Have you tried Detach Audio and Blading (B) the audio in the section that you want to mute? Commented Nov 21, 2017 at 15:02

1 Answer 1


I second what Alan commented. I would cut the part on both sides you want to mute and do the speed change on it. You might also consider a J cut from the following normal speed clip. Double clip in between the video and the sound and it should expand. Now you can extend the audio from the normal speed clip towards the end of the clip which was sped up.

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