Synergy effects with mobile (audio and) video telephony

Despite the progress in technology, mobile video telephony (MVT) is not used on a large scale. In a quest to explain the latter, we adopted a user-centered instead of technological perspective, where the influence of screen size on the synergy of audio and video was under investigation. 54 participants conducted an experiment in which the intelligibility of a standardized video-listening test was determined for three screen sizes: mobile phone, PDA and PC monitor. A significant increase in intelligibility for the large compared to the small screens was found. Moreover, a signal-to-(white) noise ratio of -9dB significantly limited the intelligibility of the videos. With respect to the Quality of Service of MVT, two conclusions result: 1) the display size should be maximized and 2) already limited amounts of noise decreases intelligibility. Consequently, we emphasize the need for both technological development and user-centered research on MVT