Frequency and amplitude estimation of the first peak of head-related transfer functions from individual pinna anthropometry

Abstract

The first (lowest) peak of head-related transfer functions (HRTFs) is known to be a concha depth resonance and a spectral cue in human sound localization. However, there is still no established model to estimate its center-frequency F1 and amplitude A1 from pinna anthropometry. Here, with geometries of 38 pinnae measured and their median-plane HRTFs calculated by numerical simulation, linear regression models were evaluated in estimating F1 and A1 from 25 concha depth and aperture measurements. F1 was best estimated (correlation coefficient r = 0.84, mean absolute error MAE = 118 Hz) by lateral distances from the base of the posterior cavum concha to the outer surface of the antitragus and antihelix (longest measures of concha depth). A1 was best estimated (r = 0.83, MAE = 0.84 dB) by the lateral distance from the ear-canal entrance to the side of the cheek near the anterior notch (shortest measure of concha depth) and by the equivalent diameter of the concha aperture. These results suggest that the first resonance's quarter-wavelength corresponds to the longest lateral extent of the concha and that its energy lost to the surrounding air depends on the concha aperture and the cavum concha's shortest lateral depth.

Further observations on a principal components analysis of head-related transfer functions

“…One future line of investigation would be to estimate the eigenmode weights from pinna anthropometric measurements that are readily accessible — similar to previous work that estimated the HRTF peaks corresponding to concha-depth 10 and pinna-vertical 11 resonances. This would allow to obtain individualised HRTFs while bypassing detailed pinna imaging and acoustic simulation.…”

“…While estimation of various types of dimensionally reduced HRTFs from head and pinna anthropometry has been reported in several previous PCA-based studies e.g. 14–16 , none have yet attempted to use the more comprehensive list of pinna anatomical landmarks 10,11 , distances between which were shown to include acoustically highly relevant measures.…”

“…The head and pinna geometries used here were identical to the data described in previous publications 10,11 . Briefly, geometries of 19 adults were measured by MRI with either a Siemens 3.0 T Magnetom Trio (5 women and 13 men) or a Shimadzu-Marconi 1.5 T Magnex Eclipse (1 man) installed at the Brain Activity Imaging Center, ATR-Promotions Inc. (Kyoto, Japan).…”

“…The FDTD acoustic simulator was described and evaluated previously 8–10,17 . Briefly, the acoustic pressure and particle velocity were calculated in a leap-frog fashion in time and on a staggered 3D spatial grid encompassing the head down to the neck.…”

Current Use and Future Perspectives of Spatial Audio Technologies in Electronic Travel Aids

“…For instance, Middlebrooks [130] reported a correlation between pinna size and center frequencies of HRTF peaks and notches and argued that similarly shaped ears that differ in size just by a scale factor produce similarly shaped HRTFs that are scaled in frequency. Further evidence of the correspondence between pinna shape and HRTF peaks [123,131,132] and notches [125,133,134] is provided in a number of following works. The use of such knowledge leads to the effective parametrization of structural pinna models based on anthropometric parameters, which suggests an improvement in median plane localization with respect to generic HRTFs [135,136].…”