[Phanx]

You can't detect when a specific sound is played (unless it was played by the UI code or an addon) but you can detect when a spell is cast.

Try this:

local f = CreateFrame("Frame")
f:RegisterUnitEvent("UNIT_SPELLCAST_SUCCEEDED", "player")
f:SetScript("OnEvent", function(self, event, unit, spellName, _, lineID, spellID)
	if spellID == 192657 then
		DEFAULT_CHAT_FRAME:AddMessage(string.format("%s was cast!", GetSpellLink(spellID)))
	end
end)