[John Casler]

Anyone know how ambiance is added to two channel audio in the studio?

Obviously, it is either a "phase" process, or some type of slight delay from one channel to the other.

If it is the latter, is it always done the same way?

That is, is the Right channel normal and the left slightly delayed or decorrelated in some way?

Oh, and I'm talking about "studio" recorded and engineered multi-track recordings

[Russell Dawkins]

John,
ambiance falls in the category of reverb although it is not perceived of as reverberation.

As you might imagine, the details of algorithm design are kept close to the chests of all players, the majors being Lexicon, TC Electronic, but in general there is a lot of processing going on - more in the best devices.

Multiple soundpaths are simulated, each with their own individual characteristics of delay and EQ. If the reverb unit is being fed a stereo signal, the ambiance or reverb will be appropriate to the source. For example, a signal component that is hard right in the soundstage will trigger reverb signals that are louder and have less delay in the right  than the left output of the reverb.

When short enough delay and decay parameters are chosen by the engineer, the "reverb" stops being identifiable as such and disappears into the subliminal realm where it is identifiable only by its absense when bypassing it experimentally.

At this degree of subtlety, it might rightly be labelled "ambiance".

[Ethan Winer]

John,

> Anyone know how ambiance is added to two channel audio in the studio? <

I do, I do!

> Obviously, it is either a "phase" process, or some type of slight delay from one channel to the other. <

Phase shift trickery is used in "widening" devices (think the "3D" setting on your computer sound card or boom box), but for ambience "Multiple soundpaths are simulated" as Russell stated. In the very old days reverb was created and added to a recording by putting a speaker and microphone in a very live room. Then EMT came out with a plate reverb which was smaller and cheaper and arguably even better. These days it's done digitally by adding as many separate echoes as the host CPU can handle.

I use plug-ins for this, and most of the better ones have a reverb density setting (which is best at maximum), and also pre-delay, high and low end roll-offs to keep bass out of the reverb etc, room size adjustments, decay time, and more. Below is a screen shot of the reverb plug-in I use most often, and here's a page that describe it briefly:

http://www.cakewalk.com/Products/Sonitus/sonitus8.asp

--Ethan

[John Casler]

Thanks guys,

The reason I ask, is on many recordings, I hear the ambiance, "more" in the right channel, but not all.

So I thought it might be a slight delay between the two, but the "decay" is almost always more evident in that channel.