This could be an interesting tech for lower-power/lighter noise-cancelling headphones: a layer of metamaterial to dampen the higher frequencies, and active elec

This could be an interesting tech for lower-power/lighter noise-cancelling headphones: a layer of metamaterial to dampen the higher frequencies, and active electronics for the remainder. I imagine there's _some_ of this already going on in the high-end headphone space, but lighter and longer-lasting headphones are always welcome.