Design, development, and testing of an inflatable earplug

Current earplugs can be categorized into the following types: roll-down foam, push-to-fit foam, premolded, custom-molded, and formable. Here, we present a new type of earplug that has the potential to be easier to insert and more comfortable than other types of earplugs. The earplug consists of a slender stem that is inserted into the ear canal, and a fluid-filled bulb that rests in the concha. The stem comprises a central core enclosed in an inflatable sheath while the bulb is formed from a bi-stable hemisphere. The insertion method for this earplug is unlike that of current earplug types. The wearer slips the stem into their ear canal, then pushes the bulb, squeezing fluid to inflate the sheath at its tip until the hemisphere pops into its stable inverted form. The inflated sheath forms a comfortable acoustic seal deep in the ear canal. To remove, the wearer deflates the sheath by pulling a tab attached to the hemisphere to pop it back to its normal state, which deflates the sheath and refills the bulb. The design of the earplug is presented, along with the results of attenuation and life tests.