hi! there have been lots of questions in the sub asking about pronunciation of ancient languages; I've taken this opportunity to round up a bunch with a view to creating a new section in the FAQ. The first bunch are generic "how do we know" posts, but you'll find additional info sprinkled throughout responses in the other threads too. Note that a couple of the threads on the Great Vowel Shift include links to videos that go into more detail. Enjoy!

How do we know?

• How do we know what ancient languages sounded like?

• How do historians know if they are pronouncing ancient names correctly?

• How do we know what ancient Egyptian words sounded like?

Great Vowel Shift

• How did English vowels sound before the Great Vowel Shift?

• What caused the Great Vowel Shift, and how do we know about it?

• How come the English of the late 130s (Chaucer etc) is so hugely different to the English of the late 1400s? More questions and examples within.

Specific languages/names

• What did the Ancient Egyptian language sound like?

• What did the language spoken by the Ancient Egyptians sound like?

• What did the Ancient Egyptian's spoken language sound like?

• Do we know what ancient languages actually sounded like?

• How is it we don't know what the ancient pronunciation of Latin sounded like, but we do know what Ancient Greek sounds like?

• What did Megas Alexandros and Julius Caesar actually sound like?

• Pronunciation of Byzantine Greek words ending in -oi.

• What do we know about pronunciation of the latin language?

• Is there any way to know what ancient Latin sounded like?

• In movies, Greeks and Romans usually have an English accent. Is it known what their actual accent sounded like?

• Do we have any clue how Latin was pronounced and how it sounded like in ancient Rome?

• Original pronunciation of "Ceasar"?

• How would Atia have been pronounced in Ancient Rome.

• How do we know "YHWH" in the Old Testament was pronounced as "Yahweh" and not anything else?

• If the letter J didn't exist in the english language before the 16th century does that mean that christians changed the pronunciation of christ's name from the Greek iesous to Jesus or was he always called "Jesus" from the beginning?

• Would the languages of the Gauls, Goths, and Celts sounded anything like modern-day French, German, and Gaelic?

• What did ancient Chinese language sound like?

• How far can I go back in time in China with modern Mandarin and still communicate with people in court?

• What is the furthest year I can go back in time to England and be able to communicate with people?

edit: a link removed

In regards to Latin, Evan Der Milner provides an excellent overview of how we know the ancient pronunciation. His basic points are:

• Grammar books and pronunciation guides written by the ancients themselves - They themselves discussed how to pronounce certain words etc.
• Translation of proper names and places into other languages preserved the original sounds
• Comparing the development of the modern-day Romance Languages over time
• Spelling mistakes in ancient grafitti and inscriptions - they spelled it how they pronounced it!
• Poetry - we know that syllable stress follows a certain meter
• Among others