fixing echo in audio

wandering journalist wrote on 10/7/2011, 3:53 PM
Hi there, shot an interview in a museum setting, not ideal I know, but visually appealing and thought the audio would be alright because of where I had the microphone(s). But, high ceilings big spaces seem to have caused an echo. Any thoughts on how I can get rid of or lessen the echo? Something I can play with within Vegas Pro? Currently using 8.1 but not a deal breaker, because I am planning to move up with the release of 11, could be talked into 10 to hold me over.



farss wrote on 10/7/2011, 4:28 PM
Very diffiicult problem to wrangle.
Eq may help by removing the dominant frequency of the room.
The more sophisticated approach is to build a downward expander..

Vegas doesn't ship with one but no problem, thanks to what Vegas can do and does ship with you can easily roll your own. This is simple because a downward expander is the inverse of a compressor and Vegas does ship with one.

To build your downward expander duplicate the track / event and under Event Propertied select Invert. You should now hear nothing as the two signals will cancell out. Now use the compressor to adjust the second track (actually it doesn't matter if you use it on the first track) so that it is being compressed very hard, you might want to mute the other track while you do this. Once you're getting a fair amount of compression turn the other track on.

Now you need to muddle your way through adjusting ALL the controls i.e. threshold, amount, attack and release. Adjust one at a time so you get a feel for what it is doing.

With patience this can yield a worthwhile improvement or end up being a complete waste of time. I find my ears can quickly tire and I need to take a break to recalibrate them when doing these kinds of tweaks. Also a good idea to go back to the original (just mute the track with the compressor on it) to check that you really are making an improvement and not a hash of it.


rmack350 wrote on 10/7/2011, 5:06 PM
Strike the last "L" off that link and it'll work.

Good explanation of noise gates. I was reading around looking for answers to the question and it seemed like this and EQ were the main hopes.

This seems like a cake that'd be pretty hard to unbake.

musicvid10 wrote on 10/7/2011, 6:25 PM
Here is a link to an analog echo reduction technique I adapted to digital audio about ten years back. It's not a cure all, but it will reduce the temporal effects of echo in some cases. Similar to the method Bob describes above. Use sparingly for best results.

wandering journalist wrote on 10/8/2011, 9:21 AM
excellent suggestions all... thanks for the help. I will take a crack at it later today and see what I come up with! Thanks again!