146th Meeting of the Acoustical Society of America, Austin, TX, USA, 10.-14.11.2003.
Part Ia: Spatial separation on McGurk effect applying three-dimensional sounds
Klaus A J Riederer
Laboratory of Acoustics and Audio Signal Processing
Helsinki University of Technology (HUT)
P.O. Box 3000, FIN-02015 HUT, Finland
Tel: +358 9 451 2494; Fax +358 9 460 224
Email: Klaus.Riederer@hut.fi, URL: http://www.hut.fi/~kar
The dependence of sound direction on the McGurk effect [McGurk & McDonald, Nature 264, 746-748 (1976)] is less known. Jones and Munhall [Canadian Acoustics, 25 (4), 13-19 (1997)] concluded with no spatial separation dependence, applying 30º horizontally-spaced loudspeakers. Current dual study investigated the full 360º horizontal space applying head-related transfer functions (HRTFs) from a Cortex dummy head [Riederer, J. Audio Eng. Society (Abstracts), 46, p. 1036 (1998 Nov.), preprint 4846]. Dry acoustic /ipi/ and /iti/ recorded from a professional speaker were convolved with HRTFs, measured at azimuths 0º, ±40º, 90º, ±130º and 180º, headphones (Sennheiser HD580) equalized. DVcam-recorded visual /ipi/, /iti/ (and black screen) were randomly presented synchronously with the 3-D sounds using Presentation 0.20 [http://nbs.neuro-bs.com]. Totally 1024 incongruent audiovisual stimuli were perceived by eight 20-30-year-old normal hearing (<=20 dBHL) native subjects (2 female) as follows. Visual /ipi/ + auditory /iti/: /ipi/ 59.96%, /iti/ 15.63% and /ipti/ 24.02%; visual /iti/ + auditory /ipi/: 66.02%, 22.07% and 11.52%, respectfully. No significant dependence of spatial separation was found for the McGurk effect, except for reaction times. The obtained fusions were atypically weak, probably because visual /iti/ was less pronounced than visual /ipi/. [Work supported by Graduate School of Electronics, Telecommunication and Automation.]