We already have computers that can determine which sounds to cancel out. That’s pretty cool.
Sound isn’t going to be like a bullet or an electrical storm hitting the grid. I don’t think you can just make a material that blocks out sound when it reaches a certain level and allow it below the threshold. Definitely an interesting theory but I am not sure how it would be designed.
Compression thickening/thinning, which only starts after a certain rate of change. I’m not sure what materials have such a property. Then, you’d incorporate it into a composite which dissipates sound selectively in one state. One idea is a fibers of a material that matches the impedance of the fluid during quiet periods, but scatters it as impedance shifts during high-energy periods.
Maybe you could use standard shear thickening somehow, but it would be a lot harder as sound only travels through air compressively.