Most of Niffnil's species communicates through silences. Silences can differ from each other in many ways. The length, the texture, the shape. It's not quite a language as we'd think of them but they do communicate what's necessary. There had been spoken languages in millennia long past, but when ancient probes made landfall it had rendered audible speech into a weapon in all affected. For awhile it was considered rude to speak because doing so could cause serious damage. Not too long afterward it became a matter of survival. With so much of the world affected, the spoken word disappeared from most places. Writing was the workaround for awhile but in time a more direct form of communication slowly popped up.
Despite all of this, there's a few cultures on the planet that celebrate vocal sounds. It was not that these cultures weren't affected by the probes, they just weren't in giving up speech or singing or anything that comes with having a voice. When Niffnil was young, he met a traveler from one of these cultures. That traveler performed a song for him. He fell in love with it immediately.
NIffnil felt that he didn't have the skill to performing music himself. But he loved listening to it and learning about it. He spent years immersed in theory and composing but he never dared to play anything he wrote and he refused to let anyone else do it either. That was until he started wielding a gedutu.
As a wielder, Niffnil can form physical constructs out of his music. What you're looking at down there is solid walls of sound. The choruses, the verses, and lyrics made manifest. Niffnil is a master of his instrument.