I'm experimenting/prototyping 3D models to passively absorb specific low frequencies, with the idea of reducing fatigue/increasing productivity in the workplace (where making/taking calls is continuous). The 3D models are based off of a research paper by Yong Li and Badreddine M. Assouar, called "Acoustic metasurface-based perfect absorber with deep subwavelength thickness" [0].

Absorbing low (male voice; 80Hz - 300Hz, not including overtones) frequencies normally takes a fair bit of dampening material, unless something like a Helmholtz resonator [1] is used. The paper shows that a ~100x100x12mm 3D printed Helmholtz resonator may entirely absorb 125.8Hz (in an extremely narrow band). I'm uncertain about transmission losses (i.e. volume of the frequency perceived behind the material).

So far, I have created/vibe-coded a script to take the inputs: frequency and tile dimension (it's square). The output is a 3D object (.stl) which can be printed.

Today I tested my 3D model, which roughly resembles the model in the paper (1mm roof & floor as opposed to 0.2mm, because of printing difficulties), by using a DIY'D impedance tube and publicly available software [2]. The print was meant to be tuned at 125Hz, but results showed 131Hz and absorption factor of ~0.42 (lower number as opposed to 1.0 may be due to inexperience with all of this; it may be due to an imperfect test setup).

My impedance tube is made from 96mm (inner) diameter PVC tube, a Visaton KT 100 V 4 Ohms speaker, an amplifier, Motu M2 audio interface, 2 Behringer ECM8000 measurement mics and some 3D printed adapters (to hold the speaker and sample).

Nothing to concretely publicise or share so far, but am thoroughly enjoying the process of digging into a field (acoustics) completely new to me, solely out necessity and/or frustration in the workplace.

Should anyone be interested, I will share my project with HN once it has progressed to where I have something written up or worth sharing.

[0] http://dx.doi.org/10.1063/1.4941338

[1] https://en.m.wikipedia.org/wiki/Helmholtz_resonance

[2] https://mathworks.com/matlabcentral/fileexchange/931

Naive question but what would be the advantage over traditional sound isolation? (such as in music studios)