Building Ambient Beds of Sounds for Film Scenes Is Often a Waste

Our brains create a hierarchy when we are exposed to several sounds simultaneously.  There are primary, secondary, and tertiary levels. Lots of sound designers and sound effects editors begin working on projects by building ambient, tertiary, beds, in which no individual sound stands out. I think this approach is wrong-headed for most film scenes, and a waste of time, energy, and money.  Earlier in my career I began with beds.  I no longer do that, and I ask that the people I hire not do it.

Here’s why …

Film storytelling is about focus and about shifting focus in either graceful or pointed ways. Film sound is the same.  It should almost never be about trying to faithfully reproduce “reality.”  When I’m in a field of grass, surrounded by trees, there are usually many sound sources hitting my ears, several of them more or less simultaneously… wind, birds, distant traffic, insects, passing airplanes, leaf blowers, distant voices, distant music, etc.

I can try to pay attention to only one of those sounds, and I will sometimes have a bit of success momentarily.  When I try to be aware of all of them at once, I’ll fail every time.  It would be as impossible as focusing an eye on everything surrounding you at the same time.  Though all the sounds present may be entering the ear, the human brain is set up to prioritize them and only be aware of one or at most two of them at once.

(Albert Bregman did the ground-breaking scientific research on this in the early 1990s. https://www.researchgate.net/publication/213798505_Auditory_scene_analysis_Hearing_in_complex_environments)

In film storytelling we direct attention, that makes it quite different from “reality.”  We shouldn’t be trying to offer a cornucopia of possible things to attend.  If what you are after is a feeling of reality, and we usually are, then add just enough individual sounds, some more prominent or closer, and some less prominent or less close, to create a credible environment.  Adding continuous sounds under the primary and secondary sounds will often result in polluting the sonic environment rather than enhancing it. In my experience, most directors understand this intuitively, and that’s why we get far more requests in final mixes to lower or get rid of background sounds than to make them louder.

You might ask, what about room tone from the dialog track?  Isn’t that a “bed?”

In my opinion, production room tone from the shooting set is an element of the dialog track.  It’s part of the dialog. One of the jobs of the dialog mixer during re-recording is usually to minimize room tone as much as possible, except in the rare cases where it’s playing a dramatic role, and is no longer a tertiary sound, but a primary or secondary one.

When sound designing a scene, I strongly recommend starting with primary and secondary sounds.  After that, if you feel gaps when listening in the context of dialog and music, then plug the gaps with appropriate sounds, but don’t spend time plugging gaps that don’t exist.

My mixing has been criticized more than a few times, but one of the compliments I’ve often received is that the films I’ve mixed have felt “clean” and “detailed.”  I’m certain that minimizing continuous and competing secondary and tertiary sounds is the main reason.

The obligatory caveat:   All aesthetic approaches and workflows should be designed as much as possible to be compatible with the priorities of the director and one’s peers.  Obviously, if you are working with a director or a picture editor who demand five layers of sound at all times, then give them five layers of sound at all times. It’s called job security.