“Calibrating” the insertion depth of roll-down foam earplugs

Abstract

Since introduction in 1972, roll-down slow-recovery foam earplugs have become nearly ubiquitous. They are used widely in industries and by consumers around the world. Their performance has been reported in numerous journal articles and they are often part of laboratory experiments, either as the object of the study or as a reference device that is used as a control or to assure exclusion of noise from the ear to facilitate data acquisition. As such it is important to be able to describe their performance since although they generally provide high levels of protection, the amount of protection and its spectral dependence is a function of insertion depth. Real-ear attenuation results will be presented for a range of insertions from that which caps the earcanal to full earcanal insertion past the second bend. The results will be compared to published data to demonstrate how they can be used to estimate the quality of fit that was likely achieved vs that which was reported. These data will be useful to researchers who wish to “calibrate” the quality of insertion they are achieving in their own studies going forward. [The author is an employee of 3M and the research was funded by 3M.]