Room tone in 5.1 surround mixing

marvinhello

marvinhello

Well-known member
Hi all I've been curious about how room tone is used in 5.1 surround mixing, especially in a quiet interior scene. I know that one of the uses of room tone is to prevent the speakers from going dead silent (and cover the edits). in 5.1 surround mixing, how do I pan the room tone track? in the dead centre or just rear left/right, should centre speaker contain room tone or just purely dialogue?
 
Room tone usually stays in the L & R speakers with some in center to help cover edits, its rarely if ever in the rear speakers as these are mainly reserved for FX and Foley.
 
I think we discussed this a bit before. Room Tone is used to fill holes in the dialog track. So it is only where the dialog track is which is center in a 5.1 mix.

In reality it isn't used in the final, as such since there will already have been a dialog premix. In a film with a real sound post schedule.

But you do need to separate in your mind Room Tone from Backgrounds and Ambiences. Room Tone is some paste to smear around on the dialog edit to smooth things out the others are part of FX and are what the audience hears as the "world" of the film.

Also the going silent thing is kind of old news. In 35mm optical tracks with out noise reduction and in 16mm prints you never wanted to go to silence because it made the sensor act up and you got objectionable noise. There are some classic "sounds of silence" like YELLOW SKY that would be used anyplace you had a lot of air to fill. This is not an issue with digital and all 5.1 release formats are digital. And even with current optical it's not much of an issue because it's encoded in Dolby SR and that will pretty much eliminate the noise in the decoding.

And no film with a decent sound track is ever going to go silent anyway. That would mean you forgot to add the "world" of your film. Whats a story with out a world to live in? A really lifeless amateur sounding film, that's what it is.
 
Thanks everyone, now i've got some contradictory answers.... Recordingwhiz said roomtone should be in L/R and some in C. Noiz said it should stay in C...

Which one should I follow?
 
marvinhello said:
Thanks everyone, now i've got some contradictory answers.... Recordingwhiz said roomtone should be in L/R and some in C. Noiz said it should stay in C...

Which one should I follow?
Click to expand...

I've seen and heard both. Just use your ears, but there should be room tone in the C since that's where dialogue is coming out of.

EDIT: I've seen roomtone being put into the C with bleed or "divergence" into L and R..
 
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C is in 5.1... So as you're doing this in 5.1 it's C

But... when you have someone approaching from the left....you can also put it a bit in the left when needed... To fill holes for example

What I would do is for example cut out the barking dog, search for the same sound somewhere in the other takes, or in the same clip maybe, copy that part, move it to
where I deleted it first, paste....crossfades... check if it fits... adapt volume so it's not suddenly louder or silent....
And when I don't have any "free setnoise in the takes itself", I'll go to the setnoise tracks

So at the end I have 1 track (well 4 if it's wireless, boom, 2 actors), depending....
 
I don't think there is really a contradiction. If your doing a stereo track then Center is even in both L & R (Phantom Center). That is also how it's done with ProLogic encoding.

The point is that the RT is there to smooth out the dialog edits. It should go where ever the dialog is. Traditionally that is center on the big screen. On the small screen it's not so much of an issue to have your dialog spread more across the front so video tends to play more with dialog placement. But the RT should go wherever the Dialog is going, it's part of the dialog group not the FX group.
 
Also for a quick note.........room tone is also valuable to use as a basis for creating filters to take out noise. (best if the noise is a 'rhythmic' type noise) or a really high/low frequency. Use the room tone to narrow the filter, the apply to dialogue and see if it hurts the meat and potatoes of the recording.
 
There's is a lot of confusion among newbies, as to what's.. 'room tone' .. and what's.. added atmos' or BG ambient sound. It's can be rather confusing and rightly so. It's sort of the same, in the finished product.. but so different in production. I'm at a loss to write a simple, clear-cut, logical explanation, despite many years of audio production and audio post-production experience.
 
Well the really short answer is that Room Tone is what you hear when your not hearing anything. And in a well done film you, the audience, will probably never "hear" Room Tone because there is always some background and ambience going on.

The only "definition" I have heard that makes sense as to what is a background VS ambience is...
Backgrounds have a story - a city roar and you hear an ambulance or car bys.
Ambiences are "just air" - quiet field, quiet house interior, forest, etc. - there is no "story" they just are.

Now of course there is a lot of overlap depending on how you define "story".

By that definition Room Tone is an Ambience that is from the set at roughly the time of the take.
 
roomtone is needed mostly where there's a sound that you can not control. For example... a pc somewhere in the room or other room but noticible which can not be shut down because other wise the earth is going to explode... Then you need to record that "noise" in the same way the rest is recorded. If you're 646486 miles away from it...record it 646486 miles away...

If suddenly in one of the shots that sound stops....you still have it to cover the rest. A continious hum is less noticible then "hum, no hum hum no hum, hum, no hum"
 
Room tone and why it is essential according to Woody Woodhall

Room tone sometimes to referred to as room noise,is a recording of the natural sound of any particular place that is being recorded in.
Room tone is the recording of the sound of the space but with no talking,no movements,and no sound other than itself.
Room tone is essential to properly edit the location sound tracks. For example in the best take of a scene there is a loud crash that happens between the the lines of dialogue. An editor will take a small bit of Room Tone and paste it over the crash. If the crash or offending noise is just lifted from the track, a gap,a bit of true silence will make the track feel as if something has "dropped out". which in turn takes the audience out of the viewing experience.
It is also used when adding recorded lines of dialogue into the sound edit of the location recordings. The sound mixer can blend the room tone and the new recordings creating the illusion of a seamless edit and replacement.

I think we can all see its easier to record and log a minimum of 30 60 seconds of room tone than in post trying to find usable frames of clean room tone it can take many hours or even days to create room tone for a project a waste of time and money.
lastly remember room tone must be free of any noticeable noises;oddly the recording of the room must be silent.
 
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