Monitor your environment in ubuntu with pulseaudiodebian packages here, and it should be in the repositories for Ubuntu).
Make yourself a little script - mine's called "hearsound.sh" - which consists of the following:
parec | pacat
Then I configured an alias to spring up a nice little terminal window:
alias hear='gnome-terminal --hide-menubar --title=listen --geometry=20x6 -x bash /path/to/script/hearsound.sh'
Invoke your script, and adjust the volume for pacat under pavucontrol. You now have passthrough audio, letting you hear your ambient environment!
(Mind you, the key tapping gets annoying on my laptop, but what the hey, right?)