Install jkmeter by entering the following commands in the terminal:
sudo apt update sudo apt install jkmeter
Description:
horizontal or vertical bargraph audio level meter for Jack Audio Connection Kit
A jkmeter displays both the true RMS level and the digital peak level. But can display stereo correlation too. . Jkmeter is based on the ideas of mastering guru Bob Katz. See
Homepage: http://kokkinizita.linuxaudio.org/linuxaudio/downloads/index.html
Version: 0.6.1-5
Section: universe/sound