When you watch words get highlighted in your reading system as a narrator speaks, the term media overlay probably doesn’t immediately jump to mind as the best marketing buzzword to describe the experience. But what you are in fact witnessing is a media type (audio) being overlaid on your text content, and tech trumps marketing in standards!

The audio-visual magic that overlays enable in EPUBs is just the tip of the iceberg, however. Overlays represent a bridge between the audio and video worlds, and between mainstream and accessibility needs, which is what really makes this new technology so exciting. They offer accessible audio navigation for blind and low-vision readers. They can improve the reading experience for persons with trouble focusing across a page and improve reading comprehension for many types of readers. They can also provide a unique read-along experience for young readers.