Subject:echo removal revisited

Posted by: analogmusicman

Date:7/29/2007 10:40:00 AM

from reading prior posts, I've got the idea that removing echo's like that reverb sound of singing in a big,cavernous church are just about impossible to remove. I've read that Adobe Audition (Cool Edit)has some sort of filter for this. does THAT work or does it just REDUCE it? any ideas?

thanks,

ps: in order to post this (posting USED to work even with nothing showing up in "my software") I had to go through registration again. will this cancel out my MP3 registration?

Subject:RE: echo removal revisited

Reply by: musicvid10

Date:9/3/2007 7:08:11 PM

You may have missed the original post, since it was made a few years back.
Although nothing can eliminate echo in a recording, it can be reduced.
This approach, which is nearly forty years old, can often produce significant reduction in spatial echo, when used judiciously.
We used it to make acceptable demos from bar band tapes.

Quote:
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Here's an old trick (from and old dog) dating back to analog recording days that usually gives some improvement (you need a good wave editor like SoundForge):

1. Select All, then Copy the audio.
2. Paste to a new track, invert the waveform, and apply moderate compression.
3. Reduce the new track volume so that a preselected "quiet" area is about 50% of the level of its corresponding area in the original.
4. Paste Mix the new track into the old. Renormalize if necessary.

There should be a noticeable improvement in clarity and echo reduction because you have applied negative feedback to the areas where the echo is most objectionable. Too high a compression or too high level of the feedback track will give a "pumping" effect, however.
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Hope this helps, I have read that there are some newer software algorithms that approach this from a different perspective.

Subject:RE: echo removal revisited

Reply by: plasmavideo

Date:9/4/2007 1:57:14 PM

I can attest that this method woks better than anything else I've tried. I also have Cool Edit Pro and have used Audition, but I don't recall any specific "echo reduction" filter, unless it is in V2.0 of Audition, or in the latest Adobe incarnation.

You do have to tinker with the compression ratio and attack/release quite a bit to make it sound relatively natural though.

This technique did help me rescue a number of otherwise hard to listen to recordings.

Subject:RE: echo removal revisited

Reply by: musicvid10

Date:9/5/2007 10:24:55 PM

Tom,
While we're on the subject (again), can you give some pointers for adjusting the attack/release delay to optimize the audio clarity?
You obviously have a handle on this, and I haven't spent as much time on it as in refining the feedback compression/level settings.
Thanks for any hints you can provide. I occasionally have video shoots where parts of the audio feed are clipped and the only way to salvage them is with ambient backup recordings.

Subject:RE: echo removal revisited

Reply by: plasmavideo

Date:9/7/2007 5:37:33 AM

I'm headed out in the field today for a production, but I'll try to think of some tips over the weekend.

My basic way of doing it in the past involved using either Vegas or Cool Edit as a multitrack editor with the 2 different files on different tracks, but with SF you can now do a quasi multi-track for the same purpose.

As to attack/release, it depends on the characteristics of the ambience. I've also had better results having a longer attack time than release time in some cases.

I'll pull up an old project this weekend and see if I can recall the settings.

I've also used a modification on this technique for noise reduction, and I'll explain that too.

T