Audio Engineering Society Convention Paper 6224 Presented at the 117th Convention 2004 October 28–31 San Francisco, CA, USA This convention paper has been reproduced from the author's advance manuscript, without editing, corrections, or consideration by the Review Board. The AES takes no responsibility for the contents. Additional papers may be obtained by sending request and remittance to Audio Engineering Society, 60 East 42 nd Street, New York, New York 10165-2520, USA; also see www.aes.org. All rights reserved. Reproduction of this paper, or any portion thereof, is not permitted without direct permission from the Journal of the Audio Engineering Society. Can playing a computer game affect perception of audio-visual synchrony? Peter WARD, Slawomir ZIELIŃSKI, and Francis RUMSEY Institute of Sound Recording, University of Surrey, Guildford, Surrey, GU2 7XH, UK ABSTRACT The investigation aimed to discover the effect of involvement in an interactive task on the perception of audio-visual asynchrony in a computer game environment. An experimental game was designed to test the investigated phenomenon. The experiment tested only audio lag conditions. It was found that within the confines of the experimental method, the threshold of perception was increased in the interactive game condition by approximately 40 ms (±20 ms), which is a small but statistically significant value. 1. INTRODUCTION The attainment and maintenance of audio-visual synchronicity has been a vital element of multi-media delivery systems since the very first experiments with synchronized film sound. The tolerances of the human perceptual system to multi-modal asynchrony have been researched for passive linear delivery systems such as film and television, but very little research has been carried out to determine the possible effect of interactivity on these tolerances. Such research might enable a set of recommendations to be drawn up for interactive media developers and manufacturers of related equipment, such as virtual reality (VR) systems and dedicated games consoles, describing the maximum permitted delay between the onset of visual and auditory events. A similar recommendation already exists for television broadcast systems in the form of the ITU-T J.100 recommendation, which specifies a maximum allowable Stimulus Onset Asynchrony (SOA) of 20 ms for audio lead conditions and 40 ms for audio lag conditions [1]. In terms of the benefits to interactive hardware and media developers, the existence of the human perceptual tolerance to asynchronous stimuli means two things. One is that it may be possible to relax development or manufacturing tolerances. The other is that a short delay between the visual event and the corresponding auditory event could be intentionally created to allow more time for real-time audio processing. Either way, the advantage would be that the impression of audio-visual synchronicity is maintained because the delay is never greater than the threshold of perceptibility.