Don’t forget the noise!
I was watching an interesting documentary the other day that had obviously spent most of its budget on traveling around the US and Europe in pursuit of interviews. They captured a fascinating depth and breadth about the subject by literally going the extra mile. While there wouldn’t be much of a film without this footage, the dialogue tracks sounded ‘choppy’ and low-budget. As a sound engineer it struck me how easy it is to overlook simple, relatively cheap post-production sound techniques that can dress up hard-won interviews into dialogue tracks that sound natural and continuous.
When the filmmakers got back to the editing room with these interviewee’s stories, naturally to avoid jump cuts they go to B-roll whenever they want to interrupt an interviewee to cut the story shorter. This helps cut out the fluff, shorten the interview, and hopefully help it flow. The astute viewer will see this happening during cuts to fidgeting hands or a shot of them walking around earlier in the day, or a sudden shot of the surroundings. The trick is to keep these cuts smooth so as to make the soundtrack appear like it is one continuous, natural speaking event. The trouble, however, is finding a natural place to cut someone off and then blend unrelated sentences together that could be minutes apart - and much different in tone quality.
Enter dialogue editorial. Once the director & editor have decided on how the interview should be cut, sewing up the disparate speaking levels and abstract sentence rhythms into something that flows is the job of the dialogue editor. Most will probably tell you that their primary tools are level adjustments and room tone.
Techniques like levels adjustments and audio crossfades are self-explanatory and par for the course: the idea is to get the perceived volume of the beginning and endings of phrases to flow smoothly in a natural way. If the interviewee got closer to the mic during a sentence, the sound engineer rides the level to keep it consistent. Et cetera, ad infinitum.
Proper use of room tone, however, seems like an obscure art when building a smooth interview track, but it is actually not hard to learn. When all that editing and cutting to B-roll results in gaps between phrases, the dialogue editor inserts a length of clean, natural background ambience between phrases and crossfades it into the two existing clips before and after it. Linearly, on a timeline, this looks like: |PHRASE 1|–x–|ROOM TONE SEGMENT|–x–|PHRASE 2| where the –x–’s are crossfades between clips. With good clean room tone (which should always be recorded on location) the audience will never know that a natural-sounding 4-minute interview was actually born from 6 hours of footage.
