Tru'nembra, The Flautist of Azathoth, is an Outer God who resides eternally in the Court of Azathoth. Tru'nembra does not possess an instrument for he himself is an instrument. He is made entirely out of visible noise and is seemingly unintelligent, just like his master. When Tru'nembra is summoned, it brings along the maddening symphony it uses to keep its master asleep, bringing insanity to those who are unfortunate enough to hear its blaring chaos. Tru'nembra had only been summoned once which was during the time when the flying polyps escaped from the tunnels the Yithians had forced them in, possibly hinting that the two events are somehow connected.
Behind the Mythos
This deity was expanded upon by Scott David Aniolowski.