Pinna sensitivity patterns reveal reflecting and diffracting surfaces that generate the first spectral notch in the front median plane

Finite-Difference Time Domain (FDTD) acoustic simulation was used to calculate Pinna-Related Transfer Functions (PRTFs) of the KEMAR manikin´s DB60 pinna. A baseline set of 25 PRTFs were first calculated at regular intervals of elevation angle in the front median plane. The simulation was then repeated 1784 times, corresponding to every unique, single-voxel perturbation of the pinna´s outer surface geometry. All perturbed PRTFs were compared with the baseline set, in order to precisely quantify the frequency shifts in all the spectral peaks and notches up to 14 kHz. This paper focuses on the pinna sensitivity patterns for the first spectral notch Nl, known to be an auditory cue to elevation in the median plane. In particular, Nl sensitivity patterns revealed the elevation dependence of broad areas of the pinna´s upper structures that are involved in reflection, and the role of the tragus region involved in diffraction.