A study was conducted to characterize the relationship between audio and video quality and the perceived quality of entertainment video services. A multiplicative model using perceived audio-only quality and video-only quality parameters was found to account for 98% of the variance in the mean opinion scores for overall audiohide0 quality. The unique feature of the model is that it predicts overall audiohide0 quality in terms of separate audio-only and videoonly perceived quality, rather than from separate audio-only and video-only impairment levels. Since the model is not defined in terms of specific impairments, but instead in terms of people's perception of quality, it is likely that the model will apply to other types of audio and video impairment combinations as well. This hypothesis has been supported by the results of subsequent research. The model may prove to be extremely valuable to system designers since it allows a costbenefit analysis of how changes in the relative quality of either the audio or video channel affect overall audiohide0 quality.