A ticker-tape synesthete sees speech as it is heard: words scroll, hang in space, or print across an inner display. Some see their own words too, as they speak them.
The experience varies in vividness from a faint automatic spelling-out to text vivid enough to interfere with listening in noisy rooms. As usual for synesthesia it is involuntary; the subtitles cannot be switched off.
The form was noted in the 19th century, then largely ignored until recent studies picked it back up as a window into how tightly reading circuitry can weld itself to hearing once a person becomes literate.