The translation of voice-over texts presents similar challenges as subtitle translation. The voice-over texts, too, must match the rhythm and length of the original. However, while subtitles must be timed with a rapid rhythm and frame-exact precision, voice-overs must start just after the original voice begins and finish with enough time for a pause before the next cut or before the next speaker begins. The texts themselves must be easy to pronounce and sound good. Every sentence must by rhythmically balanced.
The best solution for many documentary films is a mixture of techniques: on-screen speakers are subtitled while off-screen narration is recorded as voice-over.