Anthropometric earplugs with exchangeable microphones for reproducible measurements at the ear canal entrance
* Presenting author
Measurements of Head-Related Transfer Functions and Headphone Transfer Functions require positioning a microphone at the (conventionally blocked) ear canal entrance. The common approach is to modify foam earplugs or silicone domes that are easily inserted into different ears to accommodate a microphone. However, the soft tissue results in a poorly defined fit in the individual ear, as well as a poor stability and repeatability between insertions. The best option would be individually made earplugs, which are, however, expensive and tedious to make.We present an open design of anthropometric earplugs for measurements at the blocked ear canal entrance that provide a deep, tight and reproducible fit in virtually all human ears. The outer shape is available in 5 sizes and was designed based on the statistical analysis of several hundred ear canal scans. The earplug design includes a recess to accommodate a MEMS microphone. Thus, the same microphone can be conveniently used in different earplugs without losing any accuracy, and the microphone can be removed for calibration. The 3D models are made freely available. From these, the earplugs can be 3D printed in silicone with only minor manual working steps necessary.