Objectivization of the occlusion effect induced by earplugs in laboratory conditions—Effect of earplug type, insertion depth and background noise levels

Abstract

Blocking the earcanal’s entrance with an earplug can lead users to experience discomforts, one being the occlusion effect (OE), typically described as a distorted perception of one’s own voice. This discomfort sometimes causes users to misuse or remove their earplugs which significantly lower their efficiency. Reducing the OE generated by earplugs is therefore critical to make them more comfortable. However, assessing the OE is cumbersome and time-consuming as participants’ feedback is required. Moreover, the influence of factors on the OE, namely, the type or earplug, the insertion depth, and the background noise level, remains to be understood. Hence, this ongoing research aims at objectivizing the OE induced by earplugs during speech. To do so, the OE is assessed in laboratory conditions with 30 normal hearing participants using a questionnaire and by using surrogate earplugs for in-ear microphonic measurements. Various sound pressure level-based indicators are proposed and correlated to the (dis)comfort during the objectivization step. Multiple combinations of earplugs, insertion depths and background noise levels are tested to obtain a ranking of the conditions generating more or less OE. The objectivization of the OE will be a useful tool for manufacturers developing new earplugs without requiring participants’ feedback.