I feel like we are ways out from seeing anything like it. From what I’ve seen non-Newtonian fluids typically take a decent amount of energy to stop something and sound wouldn’t have much energy compared to something like a bullet.
On a sidenote does Decibullz own a patent on percussive hearing protection or am I looking up the wrong term? I feel like there must be other hearing protection out there that is effective against sudden loud sounds.
It’s a bit oversimplified, actually. Sound bounces off of discontinuities in the medium, which is why foam works. You just have to control the scattering somehow.
The big problem with using oobleck or whatever is it responds to shear, and shear can’t travel through air. You could use it for earthquake protection, though, or if you could channel compressive waves from the air into shear form using a fancy bridge like in OP.
Also, shear-thinning fluid is a thing too.