How to monitor output sound from terminal Is it possible to read current volume or frequency of outgoing sound from terminal? I am using OS X Mavericks
You can get the volumes of the currently selected input, output and sound effects/alert device as a percentage value with an AppleScript one liner:

osascript -e "(get volume settings)"


which gives something similar to:

output volume:56, input volume:63, alert volume:28, output muted:false