Impulse noise is a category of (acoustic) noise that includes unwanted, almost instantaneous sharp sounds —typically caused by electromagnetic interference, scratches on disks, gunfire, explosions, pickleball play, and synchronization issues in digital audio. High levels of such a noise may damage internal organs, while impulses exceeding 180 decibels begin to present a risk of rupturing the tympanic membrane if hearing protection is not worn. The U.S. Department of Defense has established criteria for equipment that produces impulse noise at levels above 140 dB peak SPL and requires hearing protection be worn to prevent damage human ears.