  This study provides a comprehensive test of a head-related impulse response
(HRIR) cues for a spatial auditory brain-computer interface (saBCI) speller
paradigm. We present a comparison with the conventional virtual sound
headphone-based spatial auditory modality. We propose and optimize the three
types of sound spatialization settings using a variable elevation in order to
evaluate the HRIR efficacy for the saBCI. Three experienced and seven naive BCI
users participated in the three experimental setups based on ten presented
Japanese syllables. The obtained EEG auditory evoked potentials (AEP) resulted
with encouragingly good and stable P300 responses in online BCI experiments.
Our case study indicated that users could perceive elevation in the saBCI
experiments generated using the HRIR measured from a general head model. The
saBCI accuracy and information transfer rate (ITR) scores have been improved
comparing to the classical horizontal plane-based virtual spatial sound
reproduction modality, as far as the healthy users in the current pilot study
are concerned.
