How to compare spectra of 2 recordings of same event


I have 2 stereo-recordings of a speech/discussion event. Since the room was a circular dome, there is a lot of echo in one of the recordings (much less in the other), making the voices difficult to understand. So I want to identify the frequencies of the echo to dampen them. But I can’t figure out how to analyse and compare the spectrums of the two recordings in order to identify the echo-frequencies. Both recordings are loaded into Audacity and synchronized in time. I have tried studying Plot Spectrum - - but I can’t see how I need to use it.
(Next question would be which Effect to use to dampen the specific frequencies. :sunglasses: )

Thank you!

(I have already improved the sound significantly with compression and noise reduction.)
(I use Audacity 2.1.3 on Windows 7 Home Premium 64-bit SP1)

I have 2 stereo-recordings of a speech/discussion event.

Why not just use the better recording?

Are you using Analyze → Plot spectrum? You may see a difference between the recordings, or you may not.

In general, you can’t remove reverb-echo. The reflected frequencies are, of course, the same as the original frequencies.

But, somebody does make a [u]De-Verb plug-in[/u]. It’s not free (there is a free trial) and I don’t know if it works in Audacity.

The better recording is only better for the main speaker, not for the rest of the participants. So I need to switch back and forth between the 2 recordings.

I couldn’t see ANY difference. So I am wondering if I am using that analysis correctly.

Yes. That’s why I would only dampen them, not remove them completely.

OK. Thank you! I will take a look at that.

The $80 “spl_de-verb_plus” does work in Audacity on Windows.
This free “transient” VST plugin does something similar …

Now I have installed the “VST Transient” plugin in Audacity and I have tried using it. But I am a bit puzzled as to how it can help me dampen the echo of the circular dome? Can anyone explain how to use it for that? Thank you!

I tried the SPL [u]De-Verb plug-in[/u]. It didn’t have any noticeable effect (and I had to install Reaper to make it work…) So the company advised me to try a professional tool called iZotope RX6 from . BUT why hasn’t anyone pointed out that Audacity has a built-in effect called Reverb?!? I am going to try that now! It looks quite more advanced than the SPL De-Verb plug-in(!)

The Audacity “Reverb” effect creates reverb and adds it to the sound.
“De-verb” effects attempt to remove reverberation from the sound.

“Transient” VST is a dynamic-range-expander : it attenuates the sound when it goes below a threshold …
''Transient'' is an expander--- attenuating the sound below threshold volume.gif
It only reduces the reverb a little bit.

Even the most expensive software cannot cure a bad case of reverb.

I didn’t want to ‘start all over’ with a huge professional tool like iZotope RX6, so I marked about 0.15 sec. of reverb at the end of a man with a deep voice saying a word that didn’t end with ‘s’ or ‘t’ or the like, and then I used that as Noise-profile for a normal Noise Reduction with the following parameters: 12,9,3. It’s not perfect, but better than nothing. The only strange thing is that it seems to work OK until somewhere near the end of the 1h:20m recording…? Maybe someone opened a door and thus changed the resonance frequencies of the room(?)