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sweeney · Posted - Wed Jan 17, 2001 9:33 am

I need to remove room echo/reverb from
a live recording of a stage play.
Can anyone point me in the direction
of how to solve this problem?

Syntrillium M.D. · Location: USA

Hi there. This is not really possible. At best, you could use something like the Hiss reduction, to 'gate' out unwanted reverb tails or extended echoes. But as far as totally removing room sound/echo from a live recording, there are some phase-invert tricks you could try, but the reality is that you would probably introduce more artifacts than desirable.

Were the mics very far away from the stage?

---Syntrillium Support

sweeney · Posted - Wed Jan 17, 2001 11:46 am

Yes, mics were quite far from the stage.
If I could find a single sound like
a click, assume its a step funtion,
could you then model the reverb function,
and deconvolve?

Syntrillium M.D. · Location: USA

Hmmm...deconvolving. Well, the problem that I see would simply be that it would be nearly impossible to capture the sound of the room as it was during the performance simply because of (a) people filling the hall, (b) equipment in the hall, not to mention the actual distance from which the original room sound was recorded. YOu would more than likely create a more bizarre sounding de-convolved track, if you were even successful enough to remove most of the room ambience. Controlled environments, maybe...but a live hall (with different attributes), pretty unlikely.

---Syntrillium Support

sweeney · Posted - Wed Jan 17, 2001 3:43 pm

Capturing the sound of the room is done
with the click. If you can find a click,
like something hitting something, you can
assume that is a clean impulse, which you
know what that should look like. Then look at what it looks like on the recording. The difference, is a function representing the
room environment. Take that environment
function and deconvolve (or subtract).
We can do this with image processing, where
instead of room echo you have something
out of focus or an aberration in the optics.

Syntrillium M.D. · Location: USA

Hello again. Yes, I'm aware of the process and of it's use in optics; but as mentioned in my previous post, the factors involved are a little more variable when it comes to room sound...Was there a heating vent going that night? Will there be when you take your clean impulse? All of these things (including the attendance in the room that night, people, equipment, etc) factor into play. A click of the hall empty, (controlled) will not be the same as the ambience that was recorded when it was filled.

Good luck.

---Syntrillium Support

Edited by - syntrillium support on 01/17/2001 3:53:12 PM

sweeney · Posted - Thu Jan 18, 2001 3:33 pm

I guess I was not clear. The idea
is not to click an empty hall. The
idea is to try to find an impluse or
click already on the recording. Thus your
are already in the recorded environment.

invader9000 · Posted - Fri Jan 19, 2001 6:21 am

Can you try the singer's voice? The singer's voice may be a good start because you know how the voice sounds and you can hear how reverberant it got in the live recording.