Unlike earmuffs, which cover the entire ear, earplugs fit inside the ear canal. The most common and least expensive earplug is the moldable foam variety, which expands after insertion to provide a snug fit. Foam earplugs are generally worn once and discarded. They are quite effective at blocking noise when properly fitted. Earplugs are generally less expensive than earmuffs but they are also less durable.
Pre-moulded earplugs are flexible, tapered inserts that are pre-formed to fit the ear. They are more expensive than foam earplugs but can be washed and reused several times before being discarded. The effectiveness of pre-molded earplugs is limited by how well they fit inside the ear canal. In general, their noise attenuation performance is no better than foam earplugs.
Custom molded ear plugs are cast from the user’s own ear canals. Contrary to common belief, this custom fitting does not ensure that they will provide better noise protection than other types of earplugs.
Semi-insert ear plugs, also known as canal caps or semi-aural devices, consist of two ear plugs held over the ends of the ear canal by a rigid metal or plastic headband. These devices are easily inserted and removed, which makes them good for certain work environments, although the level of hearing protection is typically less than that afforded by other types of earplugs.
Earmuffs create a seal around the outside of the ear to prevent noise from reaching the inner ear. They are held in place by a metal or plastic band, effectively providing a pressure fit.
There are two main types of earmuffs: passive and electronic. Passive earmuffs, the most common choice in industry, utilize acoustic foam inside the muffs (or cups) to block incoming sound waves. Electronic earmuffs employ circuits to amplify or attenuate certain sounds or add other specialized features to the earmuff. For example, Active Noise Reduction (ANR) earmuffs use sophisticated phase-reversing circuitry to cancel incoming sound energy.