Atmosphere sound is the most abstract of all of these categories. Dialogue, soundtrack and effects are all added to your film on purpose to add one thing or another. Atmosphere is recorded inadvertently and is mostly an artifact present in your other recordings that you will constantly have to work with and around.
When you record sound in a room it is always ‘tainted’ by some sort of ‘silence’ known as ‘room sound’. Silence is almost never silent and in different rooms the atmospheric sound will be different. This in turn means that cutting between shots from different locations will cause a shift in the auditory landscape and make your cut jarring and highly noticeable to your audience. To help avoid the jarring effects of atmospheric shift, record a few minutes of neutral ‘room sound’ or ‘atmo’ from each location to use in the edit later as editor’s ‘sticky-tape’. If you cross fade the atmosphere from different locations subtly then viewers won’t notice the change. Be sure to keep your (noisy humming) lights and cameras and any other equipment running while recording the atmosphere because they will inevitably contribute to your room’s sound.
Sound can add texture and realism to your project, the sound of plane motors in the background of a hangar, the shrill umpires whistle and thud of grass and dirt crunching underfoot during a soccer match. These atmospheric sounds can be desirable and add extra layers to interviews and scenes. It is important however on location to analyse the quality of sound around you, and try to minimize distracting and unnecessary sounds. Fridge hum and air conditioners are pretty common, and they can really ruin the sound in an interview. Our ears manage to prioritise and level the sounds in our environments quite well, but recording equipment does not share this virtue. What you record is what you’ve got to work with. While there are some ‘hum-reduction’ softwares, most will leave you unsatisfied, and chew up a lot of time tinkering with the settings.
The easiest, and best solution, is to record what you want well the first time. So take a bit of time to set up, and really figure out what is in your control. Shut the doors and windows that let in unwanted street noise, turn off as much electrical equipment as you can and listen for anything else, a dripping tap? Maybe get your talent to take off that necklace that is clicking and clacking when they are talking, you could even make your producer put down that piece of paper they are playing with, that keeps ruining the takes. If you have to live with a sound then, if you can, make sure it is contextual to the shot, or if you can’t, get a separate shot of the noisy offending item. People will forgive strange noises easier if they know what they are. Otherwise they are very distracting and possibly comic.
When we were filming the Working on Country conference, at Calperum Station, the whole place was punctuated by the sound of the noisy generators that powered the campsite. There was no way we could get them to shut down the power of the whole place while we filmed, which was all day every day, meaning we had to live with the sound, even in our precious interview sound. This meant we got shots of the generators along with our other establishing shots, so that in our storytelling, if we chose to, we could explain the presence of such a distracting and irritating noise. Unfortunately we didn’t manage to get the hero shot of someone turning the generators on, which would have told a story beat, the beginning of the conference, and excused the presence of the sound. Instead we got a disembodied generator rumbling away in the sun. This shot was less useful, and the lack of a suitable explanatory shot chewed away at our collective nails, and stole many hours of sleep from us during the edit.