If I had to guess I'd say that standing waves don't leave the chamber.
It will also capture only a limited volume.
> The mathematically designed, 3D-printed acoustic metamaterial is shaped in such a way that it sends incoming sounds back to where they came from, Ghaffarivardavagh and Zhang say.
That's certainly not what a sound engineer wants. The usecases are a little different, containing noise in an MRI machine (which has low freq rumbles) or away from ground for a drone. The word droning sound is probably not a chance homophone.
They can scale the structure as needed, so potentially for low frequs, and fit many next to each other to form a wall.
The helical structure in the ring is like a long winded pipe I guess? It's literally analogue to an electronic low pass filter from an inductor in series between source and ground, without a recipient. What a sound studio needs instead is a capacitor to ground in parallel to the recipient.
