It’s easy to record the sounds you hear on Linux with Pulseaudio. This example is using Audacity.

Prereqs

apt install audacity pavucontrol

Record what you hear

1. Audacity: “click to monitor” (right of microphone in main Audacity screen).

2. start Pulseaudio advanced configuration tool

   pavucontrol

3. Under pavucontrol Recording tab input, select “Monitor of Built-in XXX” where XXX is the playback device you wish to monitor. This loopback audio from pavucontrol allows recording what you hear in Linux using Audacity and PulseAudio.