# Perceptual Quality of Audio-Visual Content with Common Video and Audio Degradations
## 10 Conclusions  
In this paper, we compile and analyze the results of three psychophysical experiments designed to measure the perceived overall audio-visual quality of sequences. In these experiments, impairments were inserted in the audio and/or the visual component of the sequence. An statistical analysis allowed us to understand how audio and video distortions affected the overall audio-visual quality individually and jointly. A separate analysis of the distortions confirmed that visual degradations significantly impact the overall perceived audio-visual quality. Audio impairments seemed to have a weaker effect on the overall audio-visual quality, although certain degradations (Background noise and Clipping) showed a stronger effect. We can say that these effect is independent of the type of content since these experiments were conducted using a large amount of different content material. It was also observed that participants agree more in their responses when only visual distortions were present (Experiment 1). Whenever audio distortions were introduced (Experiments 2 and 3), participants had more trouble distinguishing the different levels of quality. A joint analysis allowed us to compare the effects of equivalent test conditions in the presence (or absence) of audio and visual degradations. Audio distortions had a clear effect when responses from sequences with video-only and Audio + Video distortions (with equivalent visual distortions) were compared. Similarly, when comparing the results from sequences with audio-only and audio + video distortions, we noticed that Background noise and Clipping, by themselves, had an effect that was equivalent to the same audio degradation plus the visual distortion. Based on these results, we can assert that visual distortions are not always fully responsible for the overall perceived audio-visual quality. We observed that for certain audio degradations, the overall perceived quality was deter \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Database** & **Experiment** & **Measurement** & **SCR** & **HRC** & **Stimuli** & **Distortion** & **Participants** & **Cronbach’s \&** \\ \hline VQEG-MM & AGH\_D5 & MOS & 10 & 5 & 60 & Audio + Video & 15 & 0.919 \\ VQEG-MM & AGH\_Lab & MOS & 10 & 5 & 60 & Audio + Video & 14 & 0.916 \\ VQEG-MM & Intel & MOS & 10 & 5 & 60 & Audio + Video & 34 & 0.920 \\ VQEG-MM & IRCCynN & MOS & 10 & 5 & 60 & Audio + Video & 25 & 0.918 \\ VQEG-MM & IRCCyn\_Tablet & MOS & 10 & 5 & 60 & Audio + Video & 25 & 0.910 \\ VQEG-MM & NTIA\_cateriera & MOS & 10 & 5 & 60 & Audio + Video & 9 & 0.894 \\ VQEG-MM & NTIA\_Lab & MOS & 10 & 5 & 60 & Audio + Video & 28 & 0.907 \\ VQEG-MM & Opticom & MOS & 10 & 5 & 60 & Audio + Video & 15 & 0.915 \\ VQEG-MM & Technicolor & MOS & 10 & 5 & 60 & Audio + Video & 24 & 0.902 \\ VQEG-MM & Technicolor\_patio & MOS & 10 & 5 & 60 & Audio + Video & 24 & 0.918 \\ UnB-2013 & Experiment 3 & MOS & 8 & 12 & 72 & Audio + Video & 16 & 0.886 \\ INRS & & MOS & 1 & 160 & 160 & Video & 30 & 0.869 \\ LIVE-NFLX-II & & MOS & 15 & 28 & 420 & Video & 65 & 0.920 \\ UnB-2018 & Experiment 1 & MQS\_HRC & 60 & 12 & 720 & Video & 60 & 0.924 \\ UnB-2018 & Experiment 2 & MQS\_HRC & 40 & 20 & 800 & Audio & 40 & 0.893 \\ UnB-2018 & Experiment 3 & MQS\_HRC & 40 & 20 & 800 & Audio + Video & 40 & 0.896 \\ \hline \end{tabular}
\end{table} 
Table 14: Comparison of the Cronbach’s \(\alpha\) of all three experiments and other available audio-visual databases. mined by the audio distortions. This aspect requires a deeper analysis that might include an analysis per-content to verify the real impact of such degradations. Finally, an internal consistency analysis of the quality scores showed a high level of reliability, despite the large number of distortions and test conditions considered for the study. Conceptualization, M.C.Q.F. ; methodology, M.C.Q.F. ; formal analysis, H.B.M., A.H. and M.C.Q.F. ; writing--original draft preparation, H.B.M. ; writing--review and editing, H.B.M., A.H. and M.C.Q.F. ; supervision, A.H. and M.C.Q.F.