Volume is even in all three tracks... until I export

I’m working on a podcast with three participants (recorded on Zoom), each in a separate channel. Using both Amplifier and the volume sliders, I got the volume across all three channels to be about the same. But I exported an MP3, and in the MP3 some participants are louder than others. I adjusted the sliders in Audacity several times, but I still can’t seem to get a file where all three participants are at the same volume. What can I do? Why is this a case of “what you hear is not what you get”?

FYI, Audacity 2.4.1 on a Mac running 10.15.7 Catalina.

If you are judging equal volume visually: by equal amplitude, that is not necessarily the case.
The over-the-phone voice needs to be have a larger amplitude than the in-the-studio voice,
to be perceived as equally loud, (because the phone/zoom/skype voice lacks bass).

There are free loudness-meter plugins, which are more reliable than judging by ear.

Thanks for your response.

I tried installing the app you linked to, but it seemed the only thing it would let me do for free was install it - it said that to analyze a file I’d need the pro version.

Anyway, I tried again in Audacity, and then ran the exported AIFF file through Levelator, and got something I was pleased with.


There is a levelator-style plugin for Audcaity: LevelSpeech2.NY ,
( but it’s not psychoacoustic: it does not take into account equal-loudness curves ).

Audacity 2.4.2 has “Loudness Normalizing”. See: https://manual.audacityteam.org/man/loudness_normalization.html