An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Earplugs may be used as well to improve sleep quality or focus in noisy environments. Since they reduce the sound volume, earplugs may prevent hearing loss and tinnitus (ringing of the ears), in some cases.
US Occupational Safety and Health Administration requires hearing conservation programs which include the provision of hearing protection devices (HPDs). But this does not mean that OSHA considers HPDs to be effective.