Instrument Mic recording ==> full presence sound?

Question

A recording made using microphones placed close to the instruments, recorded at the mixer as one mono track, is missing the acoustical presence of the sound picked up elsewhere in the room.

What's a good way to post-process the track to make it sound more "present"? I have video and want the "presence" to match what you expect from the scene, and produce stereo synthesized from an acoustic model of a suitable space.

I'm using Adobe CC suite. The project is in Premiere, but I could use Audition for effects that I can't apply directly in Premiere. I'm hoping for something simple, like an acoustical modeling "effect" I can apply to the mono original.

The venue is nothing exotic: just a stage. The recording from the mixer doesn't have the same ambiance as the sound recorded from the audience, but (1) it doesn't have audience sounds either, (2) it's all I have for some of it, (3) some of the instruments have intentional amplification beyond the acoustic level picked up a far-away mic.

Edit

The Reverb Effect in Premiere sounds like what @ToddWilcox describes.

Any suggestions on how to set it to approximate this venue experience? Note: I also have two samples on Dropbox of the same recording made from stereo microphones in the front row and the "dry" mixing console recording. If someone has enough “golden ears” to tell how to make the latter sound like the former, that would be awesome.

Answer 1

It sounds like you're looking for a reverb plugin. The most common type of reverb plugin is exactly what you mention in your last sentence: a physical modelling plugin. This means it uses processing to re-create the way sounds bounce around a room. The original sound is delayed and processed in various amounts to create space.

Another type of reverb that is newer, usually more expensive, and well-suited to sound for video is convolution reverb. Convolution reverb requires an impulse response from an actual room, space, device, or other item that changes the sound or electrical signal passes through it. Most convolution reverbs include a set of impulse responses, but one great things about this type of reverb is you can make your own response files using the actual room or space that you want to re-create. Once you have selected a response file for the reverb, the pluging processes the audio that you are apply reverb to in such a way as to make it sound like the audio was recorded in the space where the impulse was taken.

Most modelling reverbs (traditional ones) sound a lot like musical reverb and are not always good for sound for video. Convolution reverbs more often sound like unusual spaces, like the inside of a minivan or grain silo, and therefore are perfect for post production sound as long as you can find or make an appropriate impulse file.

No matter what kind of reverb you use to add space to the sound, one important aspect of placing a sound in a space is the pre-delay. This is an amount of time, usually between 0 and 100 ms, where the original sound is heard without the reverb effect kicking in yet. The lower the pre-delay, the closer the original sound will seem to be to the "back wall". That is, it will sound farther away from the viewer/listener. Longer pre-delay times sound closer to the viewer/listener, but make sure the pre-delay is not so long that it sounds out of place. A rough guide to delay is that 1 ms is roughly one foot of distance. So if the viewer can see a wall about 20 feet away, having a pre-delay greater than 20 ms may sound artificial. Inside a huge warehouse, pre-delay can be longer. Remember, longer pre-delays sound closer.

All the reverb plug-ins I've seen will take a mono input and give back a decorrelated stereo output (meaning it will sound like the reverb is coming from all around). If you're not familiar with using reverb then there is a huge amount to learn that is not going to easily fit into one answer on here. If this is new to you, you might as well get your feet wet and start playing around with it. If you come up with some more questions, then SD.SE is here.