The Silent Caller
You join a voice call on Discord or Microsoft Teams using Ubuntu Linux, and despite your microphone hardware working perfectly, no one can hear you. You open the system settings and discover that your microphone volume slider has been automatically dragged all the way down to zero, or the “Mute” toggle has been flipped on without your input. This usually happens when an application attempts to take exclusive control of the ALSA audio mixer, or when the PulseAudio server aggressively tries to normalize audio levels and fails.
How to Disable Application-Level Volume Control
Many VoIP applications (like Skype or Zoom) have built-in “Auto-Adjust Microphone Volume” features. In Linux, these features often conflict heavily with the system audio server, resulting in the volume being slammed to zero.
1. Open the specific application you are using for voice calls (e.g., Discord, Zoom, Microsoft Teams).
2. Navigate to that application’s internal Voice & Video or Audio Settings.
3. Look for a setting labelled Automatically determine input sensitivity, Auto-adjust volume, or Automatic Gain Control (AGC).
4. Disable this setting.
5. Manually set the input volume slider within the app to around 80%.
How to Lock the ALSA Input Level
If the microphone mutes itself even when you aren’t in a call, you must lock the hardware volume level directly in the Advanced Linux Sound Architecture (ALSA) mixer.
1. Open your terminal (Ctrl+Alt+T).
2. Launch the ALSA mixer interface by typing: alsamixer
3. Press the F4 key to switch to the “Capture” (Microphone Input) view.
4. Use the left and right arrow keys to select your microphone (“Mic” or “Capture”).
5. Use the up arrow key to raise the volume level to your desired state (usually around the 70-80 mark).
6. Ensure the channel does not say “MM” (Muted) at the bottom. If it does, press the M key on your keyboard to unmute it.
7. Press Esc to exit alsamixer.
8. Crucial Step: You must save these settings so they persist. Run the following command in the terminal:
sudo alsactl store
This permanently saves the volume state, preventing Ubuntu from resetting it to zero upon reboot or when a rogue application requests a volume change.