It’s easy to record the sounds you hear on Linux with Pulseaudio. This example is using Audacity.
apt install audacity pavucontrol
Record what you hear
- Audacity: “click to monitor” (right of microphone in main Audacity screen).
- start Pulseaudio advanced configuration tool
- Under pavucontrol Recording tab input, select “Monitor of Built-in XXX” where
XXXis the playback device you wish to monitor.