For use in intermittent and impact noise environments, Impact Sport sound amplification earmuffs have electronics that automatically stop amplifying when ambient sound reaches 82 dB. Sounds below that level are picked up by built-in directional microphones and amplified. Baseplate chamber and nonwoven layer manage airflow to control how sound reaches ear. Units operate for up to 350 hr on 2 AAA batteries and automatically shut off after 4 hr.