Earplugs are commonly used in loud environments
to protect workers from excessive exposure to noise.
When inserted into the ear, earplugs significantly reduce
the amplitude of machine noise, measured by
NRR in decibels (dB). Other studies providing good
guidelines and interventions to reduce or totally remove
noise irritation include those by Bryan and Tempest (1973); Cocchi, Fausti, and Piva (1992);Guski
(1999); Persson and Bjorkman, (1988); and Persson,
Bjorkman, and Rylander (1990).