LONDON — Britain’s King Richard III was immortalized with the Shakespeare line, “A horse, a horse, my kingdom for a horse.”

Now state-of-the-art technology has revealed what it may have sounded like if he did indeed utter those words just before his death in 1485 at the Battle of Bosworth.

Unlike the upper-class tones of his modern successors, the re-created king’s voice has a more common and earthy twang as he recites a medieval manuscript in a display that opened Sunday at the…