Electronic earplugs

    Why not create electronic earplugs that can selectively block sound, activating only when the noise level hits a certain threshold.
    Tiny microphones inside the earplugs will be able to instantly block sounds waves that are over the accepted limit. The earplugs will also be able to amplify sounds by 15 decibels just by flipping the built in switch, but even in the amplification setting they will still block sudden loud impact sounds.