Ambience, mono or stereo?
 

People have commented here that some stereo mics are nice for ambience, as they give a good "feeling" of the room or exterior.

If you record ambience in mono, how can you make it convincing for stereo playback?

Several possibilities here - choose one, or several in combination.

1. Pan ambience center
2. Add reverb
3. Add (a short) delay
4. Add more delay/verb to on channel than the other.
4a. If you've split your ambience track to separate L+R for #4, try eq'ing the channels differently... eg. L gets more lows, R gets more highs.
5. Add some delay/verb to your dialog tracks.
6. Use a mono to stereo plugin.
7. Add efx, eg. traffic, keyboarding, telephone rings, people walking, whatever, pan efx left or right, or, if motivated, move the pan. In other words, build up a stereo environment out of multiple efx.
8. Use your pan controls with dialog, it doesn't have to be center.
9. What's wrong with mono? (just pan ambience center)

Am I right in guessing that a "mono to stereo plug-in" would just be pulling some of the stunts with reverb and delay that you mentioned above?

If we spread the effects around, as you suggest, will listeners notice mono ambience?

Are the effects used in the background? If they are and your mono recording is good quality, I suspect most audiences will be happy with what they hear. Of course, better quality audio always adds something extra to a production.

Best wishes,
Peter
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Seth,maybe this is what you mean (couldn't tell for sure): how about just using the same mono recording on two tracks (panned somewhat to the left and right, respectively) but starting at different times? I would imagine that a longer delay (seconds or minutes even) would make it less obvious what's going on.

Extreme case: split the recording in two pieces of equal duration, then use one of them for the left channel and the other one for the right. How well this works might depend on the recording, but I could see this work quite well...

- Martin

Sorry, been out on a job for a few days, saw the sun and everything!

Yes!

I don't think anybody is missing anything in mono... IMHO the choices are about making the sound sweeter. If that's the question you're asking?

Well, this is interesting but not at all what I was suggesting. "Delay" as an audio effect might range from 20 to 200 milliseconds (thousandths of a second). The point being that it somewhat replicates sound bouncing off nearby walls.

Have you ever thought you could *really* sing in the shower? Part of that experience is the close hard walls. In fact, short delays are used frequently for vocals, and the resulting (audio tech-speak coming) comb-effect filtering can frequently make vocals more understandable, more out front of the mix. If you've ever listened to Phil Collins recordings I think such delay has been used on anything he's ever recorded.

Well, I suppose that's off topic, as we're on ambience in this thread, but, the point is *simulating the experience of sound in a room with efx.*

Think about what happens when someone blows their car horn outside your window. The sound comes through the window pretty clear, and very directional. Some comes through the wall, no high frequencies and very diffuse (not very directional). It then proceeds to bounce around your room (directionality), then decays (in volume).

Starting with a mono recording of a car horn, tools such as delays, equalizers, and reverbs can be used to simulate the stereo effect (directionality) of that experience.

Thanks for the detailed replies, everyone. The impression I get is that room
tone itself would probably be OK in mono, not noticed by the untrained ear, but
that I should carefully delay, reverb, and pan background effects that I add.

It also strikes me that ambience is essentially noise (distant refrigerators,
distant traffic), and I could play with Martin's suggestion of duplicating the
room tone, with a hefty delay on one layer (just in case there's something in there that isn't so "white").