There are three options: off-camera narration, UN or BBC-style voice-over and phrase-synch. You’ll be familiar with off camera narration from watching TV documentaries where an invisible voice presents the on-screen action. In foreign language versions, a native speaker records the translated script using the original voice as a guide to timing. The original voice is then removed from the sound track and the music and sound effects remixed. It’s a method widely used in information and training programmes.
The next option is UN or BBC-style narration. This is used for conferences and for news broadcasts and TV interviews. An on-screen presenter or interviewee starts speaking in their native language. There’s a 2 or 3 second pause and then an English voice is superimposed on the original voice which is dipped below it so that it is barely audible. This style of voice-over is used for creating foreign language versions of a wide variety of programmes such as financial reports, product launches, user manuals and live event commentary.
The third option is phrase synch and this is mainly used by corporate clients for live action training material. It falls midway between UN or BBC-style voice-over and lip-synch dubbing. Although no attempt is made to mirror lip movement, translation is carefully timed so that the foreign language voice matches the original voice closely, starting a sentence when the original voice does and ending it at the same time. The original voice is then removed from the soundtrack and music and sound effects are remixed. It’s a great option if you want a more realistic style of localisation but don’t want to go to the considerably increased cost of lip-synch dubbing.