I don’t see how anything non-Newtonian would be better against sudden sounds. In fact it would be worse, as they’d get more solid and thereby transmit MORE of the noise you’re trying to block out. Or maybe they only get more rigid but their sound transmission properties don’t change at all. Either way, sounds somewhat pointless.
The only way I can think that something like this would work would be to have a molded vacuum chamber as an ear plug, with a specifically engineered sound transmission bridge inside. With too much energy trying to go through, it would break. But I doubt it would be quick enough to be effective, and they’d also be one time use, and extremely fragile.