The Volume Limiter
Ubuntu includes a feature in its sound settings called “Over-Amplification.” This allows you to push the software volume beyond the standard 100% hardware limit (up to 150%), which is incredibly useful for laptops with quiet built-in speakers. However, this feature comes with an extremely frustrating built-in safety mechanism. If you enable Over-Amplification and push the volume to 130%, and a sudden loud system sound plays (like a notification beep), PulseAudio or PipeWire will often instantly, automatically drop the master volume back down to 100% to protect your speakers from blowing out, completely destroying your audio levels.
Locking the Master Output
To maintain your desired audio levels and stop Ubuntu from automatically lowering your master volume when Over-Amplification is active, you must force the audio server to ignore these dynamic clipping events.
This behavior is deeply ingrained in the ALSA/PulseAudio interaction and cannot be disabled via a simple GUI toggle. You must edit the daemon configuration file. Open your terminal (Ctrl+Alt+T) and type: sudo nano /etc/pulse/daemon.conf (if you are on an older PulseAudio system). Scroll down until you find the line ; flat-volumes = yes. Remove the semicolon to uncomment it, and change “yes” to no (so it reads exactly flat-volumes = no). Press Ctrl+O, Enter, then Ctrl+X to save. Restart the audio server with pulseaudio -k. By disabling flat volumes, you sever the link between individual application spikes and the master volume slider, ensuring your 130% over-amplified output remains stable regardless of notification pings.