Should I bother to record sound on set if it's all done in post?
Internet Filmmakers' FAQ
These days a large percentage of a film's soundscape is designed and created in post-production. Actors record ADR (also known as 'looping') in sound booths, foley artists create sound effects, and sound designers build complex soundscapes from a whole range of sources. So if sound is done in post, should you bother recording sound on location?
The short answer is yes, for several reasons:
Firstly, for reference. It's extremely helpful in post to have the set or location sound available as a reference for the sound designer. Everything from ambience to sounds caused by physical action on set is extremely useful to help the sound designer understand the practical needs of the shot and ultimately make the sound track feel more real.
Secondly, because you may end up using some of it. Depending on the type of scene being shot and the location, it is possible to record sound that you might want to use in the final mix. Anything from incident sound effects to dialogue comes with all the ambience of the location built in. This can help you sound feel more natural.
Lastly, time. Building sound tracks and doing ADR with actors takes time. If you are able to use some of the sound and/or dialogue you recorded on set, you can save time in post by not having to re-record everything. Your actors will be happier (most actors hate looping) and your sound designer will most likely welcome any reduction in their workload, not matter how small.
So the upshot is, always record sound on set whether you expect to use it or not.