Investigation Into Consistency of Subjective and Objective Perceptual Selection of Non-individual Head-Related Transfer Functions

Abstract

The binaural technique uses a set of direction-dependent filters known as Head-Related Transfer Functions (HRTFs) in order to create 3D soundscapes through a pair of headphones. Although each HRTF is unique to the person it is measured from, due to the cost and complexity of the measurement process pre-measured non-individual HRTFs are generally used. This study investigates whether it is possible for a listener to perceptually select the best-fitting non-individual HRTFs in a consistent manner, using both subjective and objective methods. 16 subjects participated in 3 repeated sessions of binaural listening tests. During each session, participants firstly listened to moving sound sources spatialized using 7 different non-individual HRTFs and ranked them according to perceived plausibility and externalization (subjective selection). They then performed a localization task with sources spatialized using the same HRTFs (objective selection). In the subjective selection, 3 to 9 participants showed test-retest reliability levels that could be regarded as good or excellent depending on the attribute under question, the source type, and the trajectory. The reliability was better for participants with musical training and critical audio listening experience. In the objective selection, it was not possible to find significant differences between the tested HRTFs based on localization-related performances.