Part IVa : Effect of Cavum Conchae Blockage on Human Head-Related Transfer Functions

The second part of the current triplet investigation concerning various quality issues in head-related transfer functions (HRTFs) focuses on specific measurement problems. The effects of the earplugs, i.e., compressible polymer foam and moldable silicone, are reviewed from both practical and empirical standpoints. The silicone putty is likely to cause better (more repeatable) HRTF characteristics, and it is studied further. The amount of putty (while sufficient enough) changes the overall gain in HRTFs, independent of direction, but depending on the particular ear and frequency, typically approx. ±5..15 dB (≥7 kHz). The cavum conchae eigenfrequencies are not changed due to adjusting the amount of the silicone in the meatus.