"According to the app's Web site, this tool "adjusts
the audio levels within your podcast or other audio file for
variations from one speaker to the next, for example. It's not a
compressor, normalizer or limiter although it contains all three."
It's not open source software, however it's one of the few free
tools I've found that runs on Linux (as well as Mac OS X and
Windows) to get this particular job done."