An Interactive Virtual-Environment Generator for Psychoacoustic Research II: Collection of Head-Related Impulse Responses and Evaluation of Auditory Localization

This note is concerned with an interactive virtual-environment generator (the SCATIS-lab), which is currently being used for psychoacoustic experimentation at our institute. While the architecture and implementation of the system has been the subject of a prior note, issues of psychoacoustic performance are dealt with here. Starting with a description of the measurement procedure for individual head-related transfer functions (HRTFs), the interpolation technique for deriving HRTFs for directions located between the measured ones is explained. The psychoacoustic performance of the SCATIS-lab in terms of sound localization is then compared to other systems cited in the literature. Evaluation results with and without head movements show that auditory localization in SCATIS-lab-generated virtual environments and in real anechoic environments are very similar. Further, it is confirmed that both inversions and localization blur decrease considerably when the head tracker is switched on. To obtain results that can be directly compared to those found in the literature, localization experiments were performed applying the GELP pointing technique. Alternative methods were tested as well, i.e. pointing with a finger and pointing with the head. These methods were identified as being better suitable for localization experiments in interactive auditory virtual environments.