The Time Remapping tool applies time shifts only to video. Not audio. The audio linked to your video is disconnected or deleted.
However, it should have no effect on the audio on other tracks. So, if your narration, sound effects or music is on a separate track, remapping time on a clip should not remove, mute or change it in any way.
Where is your narration clip? Is it separate from the clip you are time remapping?