If you’re having trouble with your input level auto-adjusting on your mic during VOIP calls on MacOS go buy SoundSource for 10 bucks and save yourself a lot of headaches:
On conference calls we’d regularly have one person clipping and another far too quiet. We tried different VOIP software, different headsets, different environments. It all came back to MacOS being way too sensitive about autoadjusting input levels. As of 2018, there’s also no way to globally tell it to not do that.
If you google for solutions to this problem you’ll find that it’s not uncommon. Solutions range from “reset your PRAM!” (this does nothing) to “run this applescript that checks the input volume every second and adjusts it back to a hardcoded level”. The applescript worked extremely well; however, was not a tenable solution for our coworkers who just do not want to maintain an applescript.
Soundsource let’s you set a level and keep it locked in. It does way more than that, but honestly that feature alone is worth 10 bucks. It also has a nice menu bar widget, which I like using to verify what’s going on with audio settings.