The influence of video quality on perceived audio quality and vice versa

Three questions are being studied. Question one: "To what extent is the per ceived audio quality of an audiovisual stream influenced by the video quali ty?" Question two is the reverse: "To what extent is the perceived video qu ality of an audiovisual stream influenced by the audio quality?" Finally: " How do audio and video quality contribute to the overall perceived audiovis ual quality?" The quality ranges from broadcast audio and video quality to standard videophone (telephone) quality. The main conclusion is that when s ubjects are asked to judge the audio quality of an audiovisual stimulus, th e video quality will contribute significantly to the subjectively perceived audio quality. The effect is about 1.2 points on a nine-point quality scal e. The reversed effect is much smaller, about 0.2 point. Furthermore a simp le mapping from the audio and video quality to the overall audiovisual qual ity is given, and it is shown that the video quality dominates the overall perceived audiovisual quality in nonconversational experiments.