Acoustic Fields: How to Build a Diaphragmatic Absorber (2019)

I guess this will not absorb low frequency vibrations transmitted through walls, generated by neighbor living above me? :)

If you covered your ceiling (and wall which transmit sound) with such boxes, it would.

I'd figure low frequency sound could be better absorbed by active cancellation.

For those interested, the AVVA C20 active bass trap is considered the gold standard for active low-frequency control: https://www.psiaudio.swiss/avaa-c20-active-bass-trap/

active noise cancellation does not absorb (and therefore prevent transmision) of the sound, it instead just causes the sounds to be "not heard" at a small location.

Double Bass Arrays might be an interesting rabbit hole :)

Reminds me of dielectric mirrors/anti-reflection coatings, but nonlinear.