Ambience / Room tone
Watch as an animation →Lay the background sound of a place under the cuts without gaps, so it sounds like the same space even when the cut changes.
Scenes joined from separately made clips, empty stretches between dialogue or narration, and cut boundaries where the sound suddenly drops out.
The sound of generated clips has a different sense of space and noise in each cut, so joining them as they are makes the sound change or cut off abruptly at every cut. Lower or remove the clip sound, and lay one ambience track that fits the place (indoor chatter, wind, street sounds) across the whole length of the scene. Change the ambience only where the scene changes, and overlap the two briefly with acrossfade. Keep it much quieter than the narration, and avoid complete silence, because it sounds like the audio is broken.
Lay one looped room-tone recording under a whole scene and lower the clip audio to 30 percent so cuts stop jumping in sound: ffmpeg -i scene.mp4 -stream_loop -1 -i room.wav -filter_complex '[0:a]volume=0.3[c];[1:a]volume=0.5[r];[c][r]amix=inputs=2:duration=first:normalize=0[a]' -map 0:v -map '[a]' -c:v copy out.mp4. Never leave dead silence.
Not verified