The ultimate in hearing protection. Designed for musicians who want to hear naturally, need protection when hearing is at risk, and want to avoid the inconvenience of removing earplugs to hear. Music·PRO circuitry automatically changes output levels as sound input levels change. Hearing is natural, as if nothing is in the ears, until sound exceeds safe levels. As sound levels increase, earplugs gradually provide 9- or 15-dB sound reduction. Natural hearing is restored when sound returns to safe levels.