FFmpeg audio filter pipeline for speech enhancement
I just came across one article related to the compand command that might be useful (just in case someone looking for help sees this article).

From the article:


  To test this, and my understanding of compand, I added a very simple filter to remove the quiet section of the audio by decreasing their volume dramatically:

ffmpeg -i in.mp3  -filter_complex \
  "compand=attacks=0:points=-30/-900|-20/-20|0/0|20/20" \
  out.wav

  
  attacks=0 means that I wanted to measure absolute volume, not averaging the sound over a short (or long period of time). When the speaker suddenly yells, or talks back and forth with someone off mic, I want the volume adjustment to be immediate. The downside is that you may hear the volume being clamped.
  
  points is the actual volume mapping function, and I’ll walk through it:
  
  I added a mapping of -30/-900, which means that volume below -30db in the original input track gets converted to -900db (completely silent).