Echo in room problem

[ajcvideo]

How does one eliminate echo from being in a large conference room? I have Edius 6.08. Thanks.

[DigitalDave]

Correct placement of mics.
Echo is difficult to remove in post.

[createmedia]

There is no substitute for getting a good audio recording in the first place. The usual answer is to use close mics (head mics) and get a feed off the audio desk into an audio recorder and sync it up afterwards, that avoids most problems.

If that was impossible for whatever reason, then the clips can be overdubbed with the voices afterwards, but if it was ad lib speech then there needs to be a transcript produced and the speakers need to come back and record voice over to the transcript (used in film where the location audio is difficult).

However if that is impossible too, and you are stuck with an audio track with echo it is very difficult to deal with, and of course detracts from the clarity of the speech.

In rooms with large flat reflective surfaces such as floors and walls there will be not only a room resonance but also an echo.

Room resonance can be improved by adding a parametric equaliser filter and by pulling down the nodes on the 0dB line reduce the volume (notch) with a reasonable Q set. By moving the notch frequency you can find the spots that improve the sound clarity or hollowness.

Echo is a different matter being a delayed repeat of the original sound at a lower volume than the original. Effectively you need to know what the delay is and add audio back in in the opposite phase to cancel it out. Unless you accurately know the original characteristics of the room delay it remains a virtually impossible task.

Bearing in mind that an echo is a lower volume repeat you could try a sound gate but it might not help.

More reading here.

http://www.sonycreativesoftware.com/Forums/ShowMessage.asp?Forum=12&MessageID=702177

And one piece of software;

http://echodamp.com/about.html

Sorry it isn't good news, it is a really hard problem to solve in post.

Mike

[dpalomaki]

There is software (plug-ins) that claims to be able to reduce reverberation. Whether or not it will help you is an open question. My may be able to download demo versions of some.

iZotope RX3, Zynaptic Unveil, and De-Verb by SPL are three products you might want to check.
http://www.youtube.com/watch?v=I0bw_Eno534 for a review of them.
I believe there are other products as well.

As noted by others, there is no substitute for good mic placement.

[PaulTV]

read my blog here:

http://indiestereographer.blogspot.co.uk/2013/03/removing-echo-from-audio-before-you.html

it may help you out, but as suggested, there's no real fix..

Paul :-)