Influence of audio on perception and comprehension of video sequences : A SUBJECTIVE TEST OF PERCEPTION OF AUDIOVISUAL CONTENT WHERE AUDIO QUALITY WAS CHANGED

Abstract: The importance of the role audio plays in multimodal information media is often underestimated or even overlooked. This applies to a wide range of media in everyday use- from videoconferencing systems to multi modal human-computer interfaces and to some extent even computer games. When improving audiovisual (AV) systems, the focus is generally on video. A question seldom asked, most likely because it is of a difficult nature, is how we actually perceive audiovisual media. In this study the importance of audio was examined by exposing subjects to audiovisual video clips that varied only in audio quality. In some videos background noise from a subway train was added and was to be regarded as an external signal. The subjects were asked to rate their perception of the audio, video, audiovisual quality as well as the listening effort by rating the comprehensibility of the content. They were also required to pay attention to the content in each video and to answer questions about it. Results show a perceived difference in video quality following the perception of audio quality, although the video quality was never altered. Results also show that a light reverb infused in the audio signal was considered to have a positive impact on comprehensibility while still being perceived as decreasing the audio quality. The thesis has been written in collaboration with telecomunication company Ericsson and all tests and material have been recorded at Ericsson laboratories in Kista, Stockholm.