Overwriting selection with background noise (not silence)

Question

I've got to edit a voice recording (removing breath, click, ahhhs, …), but since the track is part of a video, I can't just cut the unwanted parts out, otherwise the lipsyncing would be corrupted. So how can I just select the unwanted parts and overwrite them by a sample of the backround noise? I tried already like this: I copied a long sample of silence, selected my unwanted part and inserted the silence from clipboard — problem here is, that the inserted silence is longer than the selection and therefore extends the total track length which breaks lipsync.

Answer 1

Why not use the correct length of silence. How will using background noise fix the length problem?

Silence will not be noticeable if you have a good S/N ratio. Background noise might be noticeable depending on how it matches and S/Ns.