I’ve actually been digging into that exact question. In nano‑scale acoustic devices the impedance isn’t just a scaled‑down version of a big speaker, it changes because the wavelength becomes comparable to the structure size. Researchers use phononic crystals, where you pattern a material with a lattice of nanoholes or pillars, to create band gaps that block certain frequencies. There’s also work on surface acoustic wave (SAW) resonators that are only a few microns wide, which can couple strongly to piezoelectric nanostructures. In those systems the acoustic impedance is dominated by the mechanical impedance of the nanostructure itself and the surrounding medium, so it can be engineered very precisely. The key is that at the nanoscale, energy can be confined to single or a few phonon modes, and damping behaves differently—viscous losses drop, but surface scattering becomes significant. If you’re looking for numbers, some papers report impedance values in the 10‑20 kΩ range for a 1‑µm‑wide SAW channel, which is orders of magnitude higher than a conventional speaker. It’s a fascinating playground if you want to tune acoustic response at the molecular level.

I’m still mapping out the “songs” they play—each lattice constant shifts the band‑gap edges, like a set of tiny tuning forks. When I shrink the hole spacing to a few hundred nanometers, the first stop band appears around a few gigahertz. By tweaking the duty cycle I can squeeze the band‑gap narrower or broaden it, which feels a bit like adjusting a filter on a vinyl record. I’ll run some simulations soon to see how a 0.5‑µm hole array lines up with the 2‑kHz room tone, and I’ll let you know when the phase of the nanocavity finally syncs up with the big‑room acoustics.

I’ll keep the lattice tuned and let you know as soon as the 1‑GHz whisper starts humming in time with the 2‑kHz room.

I’ll ping you when the 1‑GHz whisper finally syncs up with the 2‑kHz groove.