Effect of Occlusion on Deaf and Hard of Hearing Users' Perception of Captioned Video Quality

While the availability of captioned television programming has increased, the quality of this captioning is not always acceptable to Deaf and Hard of Hearing (DHH) viewers, especially for live or unscripted content broadcast from local television stations. Although some current caption metrics focus on textual accuracy (comparing caption text with an accurate transcription of what was spoken), other properties may affect DHH viewers' judgments of caption quality. In fact, U.S. regulatory guidance on caption quality standards includes issues relating to how the placement of captions may occlude other video content. To this end, we conducted an empirical study with 29 DHH participants to investigate the effect on user's judgements of caption quality or their enjoyment of the video, when captions overlap with an onscreen speaker's eyes or mouth, or when captions overlap with onscreen text. We observed significantly more negative user-response scores in the case of such overlap. Understanding the relationship between these occlusion features and DHH viewers' judgments of the quality of captioned video will inform future work towards the creation caption evaluation metrics, to help ensure the accessibility of captioned television or video.