Automator action to adjust volume on audio files

Question

I am looking for an Automator action (or an app with Automator support) that can adjust the volume on audio files (something like set to 150% of input file volume), preferably free.

Answer 1

How about something like SoX (free/donationware). It's features page lists wide variety of volume/level effects, including:

• Volume/level effects
  • ...
  • ...
  • vol: Adjust audio volume

According to the SoX documentation, the following should double the volume of input.wav and write it to output.wav (the value after the -v flag is a multiplier)

sox -v 2.0 input.wav output.wav

You should be able to use this in an Automator workflow using the "Run Shell Script" action.