Basic Training
Basic Sound for Video (page 2)

When you are recording sound on location, someone on your crew should be responsible for audio. It might be the camera person or it might be a separate audio person who also controls the boom microphone. This person should be listening to the audio on headphones and should also be responsible for making sure that the set is quiet before the tape rolls. Audio technicians or directors frequently call out "Quiet on the set! Tape's rolling!" before the director calls "Action," to let the crew know that the scene has started and they need to immediately cease making noise. The audio technician will also be sure to record 30 seconds or so of "room tone," which is the ambient sound of the room. People and equipment affect the acoustics of a room as sound bounces off them or is absorbed, so it's important that everybody who is in the room while you record the dialog is also in the room (but completely silent) when you record the room tone. You can use the room tone to overdub or "erase" extemporaneous noises recorded during the take. The prop masters who worked on the 1960s Star Trek television series wanted the actors' tools (phasers and communicators) to mount magically onto their clothes without visible belts - so they used Velcro. Every time Captain Kirk pulled out his communicator to call back to the Enterprise, there was a zip! noise as the Velcro detached. Overdubbing with room tone made the sound vanish. You may want to overdub the sound of a passing truck or a falling lamp off-set.

Typically, you want to avoid doing things in post production, but there are some things that you have to do in post, and it would be foolish to do otherwise: adding music is a perfect example. It would be a bad idea to have music playing during a take, because of the matching difficulties it would provide. When production crews film scenes that take place where music is supposed to be playing, they will record only the actors' dialog, while extras dance silently to non-existent music. The editor adds the music later in post.

Other things you'd want to add in post production might be sound effects. It's often best to add the squeal of brakes, honking of car horns and thunderclaps after the fact. The person who does this is a Foley artist. These artists create the sounds of galloping horses, shoes walking across floors and even the incidental sounds of utensils clinking on plates. Foley artists add almost all sound effects you hear in movies, because of the difficulty in recording them properly during the time of production.

All but the simplest non-linear video editors allow for multiple audio tracks, which let you add things like crickets chirping, dogs barking far off or nearby noises, without interrupting your dialog.

Very often audio is an afterthought during a video production. As home theaters become more sophisticated, the limitations of the original recordings become more obvious. By paying attention to sound when you record it, you'll be sure that your sound will be clear and consistent, even if it plays through unsophisticated stereo or even mono speakers. This makes a big difference in your final product.

Contributing editor Kyle Cassidy is a visual artist who writes extensively about technology.

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