A New Method for Localization Studies

Bernhard Seeber

AG Technische Akustik, Institute for Human-Machine-Communication, Technische
Universitaet Muenchen, Arcisstr. 21, D-80333 Muenchen, Germany

Summary
Many scientic studies investigate and technical applications use the acoustical
localization in the eld of vision. Therefore it is suitable to display the
perceived auditory direction by a light point. In formerly known methods subjects
use a hand-held light pointer or a pointer mounted on a revolvable axle in front
of them. However, the subject's motor system or the optical parallax may inuence
the results of those techniques. The calibration of the system and data logging
also turn out to be difcult. The proposed new method utilizes a laser pointer
with a deection unit instead, which is controlled by a computer. Subjects enter
the perceived sound direction with a trackball. The laser spot moves according to
the rotation of the ball smoothly on a dened track. A complicated mechanical
calibration can be avoided by calibrating the deection unit by a computer. The
intuitive experimental operation and the high resolution of the system make this
method particularly suitable for localization research in audiology,
psychoacoustics, and virtual acoustics. The symmetric, bimodal outlay of the
experimental task reduces interaction effects between different modalities.
Localization results for variable and xed initial laser position obtained by this
method are presented and compared to results acquired by other methods.