hi! If you specified which languages you speak, that could help narrow the field. Meanwhile, get started on this section of the FAQ which has information mainly about English, but also some on Spanish, Mandarin, Sanskrit, French, Portuguese, and Turkish:
For english to listen. You could easily adapt as far back as the 13th century I would think. However to freely communicate it would be later. Probably 16th or 17th. However they would think you ate a heretic due to how you speak. Your phrasing and pronunciations would be off quite a bit