Little trick, if you want to know what a particular sound is that is played by the UI, you can likely find out with (via /script):
Lua Code:
ZO_PreHook("PlaySound", function(name) d("Play sound: " .. name) end)
Doesn't work for everything, though.
Then there's probably one or more constant in SOUNDS (/Zgoo SOUNDS) which has that string as its value, which you can use in your own code.