A Perceptual Evaluation of Individual and Non-Individual HRTFs: A Case Study of the SADIE II Database

Abstract

As binaural audio continues to permeate immersive technologies, it is vital to develop a detailed understanding of the perceptual relevance of HRTFs. Previous research has explored the benefit of individual HRTFs with respect to localisation. However, localisation is only one metric with which it is possible to rate spatial audio. This paper evaluates the perceived timbral and spatial characteristics of both individual and non-individual HRTFs and compares the results to overall preference. To that end, the measurement and evaluation of a high-resolution multi-environment binaural Impulse Response database is presented for 20 subjects, including the KU100 and KEMAR binaural mannequins. Post-processing techniques, including low frequency compensation and diffuse field equalisation are discussed in relation to the 8802 unique HRTFs measured for each mannequin and 2818/2114 HRTFs measured for each human. Listening test results indicate that particular HRTF sets are preferred more generally by subjects over their own individual measurements.

HRTF measurement by means of unsupervised head movements with respect to a single fixed speaker

“…Contrary to a static HRTF measurement, where measures are taken to ensure that the subject does not move his/her head during stimulus reception [4], this is not the case in the current setup. As a consequence, each of the sampled directions in Figs.…”

“…Because we are interested in the directional variations of the HRTF, the diffuse field response (the direction-independent component) was subtracted from the magnitude on a per frequency basis (diffuse field equalization) [4], [35].…”

“…Since everyone has a different ear, head and torso morphology, everyone has a different HRTF. There has been a lot of research on the individual differences in the HRTF, resulting in numerous HRTF databases that can be accessed online [2]- [4]. The impact of a non-individual HRTFs on three-dimensional (3D) audio perception is often studied by considering a generic HRTF, measured on a dummy head, e.g.…”

“…accepted that an individualized HRTF is superior to a nonindividual HRTF, especially regarding sound localization [6], [7], although for some applications a generic HRTF may suffice [4], [8].…”

Interaural Level Difference Optimization of Binaural Ambisonic Rendering

“…This illustrates how AIO produces an overall improvement in PSD, regardless of the type of loudspeaker configuration. Secondly, to assess how AIO works when using other HRIR datasets, renders were made for {M = 1, M = 2, M = 3, M = 5} using individualized HRIRs from human subject H20 of the SADIE II database [47], using the corresponding Lebedev loudspeaker configurations as before. The omission of M = 4 was due to a lack of necessary measurements.…”