Odysseus fashioned the first-recorded earplugs from beeswax to protect his crew from the mind-bending effects of siren song. People were still using this material as late as the mid 20th century, until the invention of mouldable silicone plugs in 1962. Still favoured by musician's today, these devices can contain filters to let a small of high frequencies pass for a more balanced attenuation, or volume reduction.
Modern, disposable earplugs were first produced in 1972. Made from memory foam, they can be compressed and inserted into the ear canal, where they slowly expand to create a seal. Attenuation is measured in decibels, with most rated between 15 and 30dbs of volume reduction.