Chrome WebRTC and microphone gain

Summary

WebRTC in Chrome applies automatic gain adjustment to microphones. There may be an issue with pulseaudio's microphone mixer default settings since mic volume can trend to zero or maximum during a WebRTC session.

This can render the user inaudible in video conferencing software like meet.google.com, zoom, and others. For reference:

skype, hangouts, others

cisco webex

discord, jitsi meet

Workaround

This seems to be an issue with microphone gain versus microphone boost; applying the change here of setting Mic Boost to zero in alsa mixer settings appears to fix the issue of wild volume swings.

Is it possible that microphone gain is somehow being double counted with boost?

Environment

Linux Mint 20 Ulyana

pa-info.txt

Steps to reproduce

1. Set input gain of a micrpohone to 50% in the sound settings, and leave the sound settings window open to observe.
2. Attend a meet.google.com video call with a number of participants.
3. Talk for a while at varying volume. Get in a spirited discussion or attempt to speak up a few times.
4. Observe the microphone volume drifting in the sound control panel window.
5. If you become too soft to hear or unintelligible, you must manually set the slider back to 50% during the meeting.

What is the current bug behavior?

The microphone can trend to 0% or 100% rendering the user inaudible or unintelligible over video conferencing.

What is the expected correct behavior?

The volume should adjust more slowly.