How do I De-Ess a sound file with SoX?

Question

I am using SoX to create slow but pitch corrected audio files. The resulting files sound pretty good, but often have a very hard "S" sound that I would like to filter out. Many desktop programs include a "De-Essing" filter that works well, but I would like to have a filter that works on the server side.

What SoX filter and parameters should I use to De-Ess an audio file?

Edit: I should add that this needs to work on Linux.

Answer 1

While far from perfect, you may be able to get sufficient results by a suitable low-pass filter. That should not affect other parts of a speech signal too much.

Answer 2

You could use a de-esser VST such as spitfish and a command-line VST host such as MissWatson. Sox has very limited plugin support, so if you need something more specific, you're better off going the VST route.