Whenever people encounter OP for the first time, the question that immediately comes into their minds is ‘How do you know?’ The links on this page provide some answers for Early Modern English.
Articles on my website can be found in the Books and Articles section. Click on the filter ‘Shakespeare’ and scroll down to the required item.
Helge Kökeritz, Shakespeare’s Pronunciation. Yale University Press, 1953.
E J Dobson, English Pronunciation, 1500-1700. Oxford University Press, 1957.
Charles Barber, Early Modern English. Andre Deutsch, 1976.
Fausto Cercignani, Shakespeare’s Works and Elizabethan Pronunciation. Clarendon Press, 1981.